HCI and UI – Discussion

PART OUTLINE Chapter 1: Usability of Interactive Systems

Chapter 2: Universal Usability

Chapter 3: Guidelines, Principles, and Theories

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Th is f irst set of chapters provides a broad introduc t ion to user interface des ign and interact ive systems . Chapte r 1 covers usab ility goa ls, meas ur es, and motivations as well as gene ral goa ls for the HCI profession. A r ich set of resources is available at the end of the chapte r, listing impo rtant books, guideli nes, and relevan t jour nals and prof essional organiza tions.

Chapter 2 discusses universal usab il ity and exposure to the diversity of users. This includes t he cha llenges posted by physica l, cognit ive, perceptual, personality, and cultu ral d ifferences. Chapter 3 reviews t he guidel ines, pr inciples, and theor ies of the field to help facil itate good design.

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99 Designing an object to be simp le and clear takes at least twice as long as the usual way. It requires concentration at the outset on how a clear and simp le system would work, followed by the steps

required to make it come out that way-steps which are often much harder and more complex than the ordinary ones. It also requires

relentless pursuit of that simp licity even when obstacles appear which would seem to stand in the way of that simplicity . ''

CHAPTER OUTLINE 1. 1 Introduction

1.2 Usability Goals and Measures

1.3 Usability Motivations

1.4 Goals for Our Profession

T. H. Nelson The Home Computer Revolution , 1977

25

26 Chapter 1 Usability of Interactive Systems

1 . 1 Introduction

User -interface designers are the heroes of a profound transformation. Their work turned personal computers into today's wildly successful mobile devices, enabling users to communicate and collaborate in remarkable ways. The desk­ top applications tha t once served the needs of professionals have increasingly given way to powerful social tools that deliver compelling user expe riences to global communities. These invigorated communities conduct business, commu ­ nicate with family, get medical adv ice, and create user-generated content that can be shared with billions of connected users.

These life-changing shifts were made possible because researchers and user ­ interface designers harnessed technology to serve human needs . Resea rchers created the interdisciplinary design science of hu1nan-compitter interaction by applying the methods of experimental psychology to the powerful tools of com­ puter science. Then they integrated lessons from educational and industrial psy­ chologists, instruc tional and graphic designers, technica l writers, experts in human factors or ergonomics, and growing teams of anthropologists and soci­ ologists. As the impact of these mobile social tools and services spreads, researchers and designers are gathering still fresher insights from sus tainability activists, consumer advocates, citizen scientists, and humanitarian disaster response teams.

User experience designers produce business success stories, Hollywood heroes, and Wall Street sensations. They also produce in tense compe tition, copyright-infringemen t su its, inte llectual-proper ty battles, mega-mergers, and international partnerships. Crusading Internet visionaries, like Google's Eric Schmidt, promote a world with free access to information and ente rtainment, while equally devoted protec tors of creative ar tists, like singer Taylor Swift, argue for fair payments. User in terfaces are also controversial because of their central role in persona l identification, national defense, crime fighting, elec­ tronic health records, and so on.

At an individual level, effective user experiences change people's lives: Doc­ tors can make more accura te diagnoses, ai,d pilo ts can fly airplanes more safely; at the same time, children can learn more effective ly, users with disabilities can lead more productive lives, and graphic artists can explore more creative possi­ bilities . Some changes, however, are disrup tive, reducing the need for telephone operators, typesetters, and travel agents . Too often, users must cope wi th frus­ trat ion, fear, and failure when they encounte r excessive ly complex menus, incomprehensible terminology, or chaotic navigation paths.

At a societa l level, connected communities open up new forms of colJective action and policy engagement. Having more informed citizens may lead to be t­ ter decis ions, more transpare nt governance, and greate r equity when facing

1.1 Introduction 27

legal, health, or c1v1c challenges. But there may be increased dangers from extreme groups who promote terrorism, oppressive social policies, or racial hatred. The increased power of social media and collaboration technologie s means that there must be a new balai1ce of legal protections, police powers, and privacy.

The steadily growing interest in human-computer interaction stems from the designers' desire to improve the users' experience (Figs. 1.1 to 1.3 show some popular applications). In busine ss settings, better decision-support and document-sharing tools support entrepreneurs, while in-home settings, digital photo libraries, and internet conferencing enhance family and personal relationships. Millions of people take advantage of the World Wide Web's extraordinary educational and cultural heritage resource s, which provide access to everything from outstanding art objects from China to music from Indonesia, sports from Brazil, and entertainment from Hollywood or Bollywood

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28 Chapter 1 Usability of Interactive Systems

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(Figs. 1.4 to 1.5 show examples of popular websites). Mobile devices enrich daily life for many users, including those with disabilities, limited literacy, and low income s. On a worldwide scale, promoter s and opponents of globalization debate the role of technology in international development, whil e activists work to attain the Unjted Nations Sustainable Develop­ ment Goals.

The remarkably rapid and widespread adoption of mobile devices (including smartphones, tablet s, game devices, fitness tra­ ckers, etc.) supports personal communication, collaboration, and content creation. The proliferation of such devices in developed as well as developing

FIGURE 1.3 Ben Shneiderman at a standing desk with two high-resolution screens. We can see a MS Word document (wi th six pages visib le), two web browsers, and the Out look e-mail app lication in a Windows environment.

1.1 Introduction 29

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nations has been astonishing. Economists see a direct linkage between cell­ phone dissemination and econom ic growth since communications facilitate e-commerce and stimulate entrepreneurial ventures. Mobile devices also promote wellness, enable timely medical care, and provide life-saving disaster response services.

Similarly, explosive growth is the appropriate description for what's happen­ ing in the realm s of social networking and user-generated content. Older media, such as newspapers and television, have lost audiences in favor of social media such as Facebook, Twitter, YouTub e, and Wikipedia (all of which are among the top 10 most visited services). These leading websites are just a taste of what is to come, as entrepreneurs trigger ever more social media involvement accessible through web-based applications and small mobile de vices .

Designers e11able users to create, edit, ai1d distribute 3-D printed objects, imrnersive virtual reality games, interactive animations, and increasingly high­ definition music, voice, and videos. The result is ever-richer experiences and a creative outpouring of user-generated content available, even on mobile devices.

30 Chapter 1 Usability of Interactive Systems

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Sociologists, anthropologists, policymakers, and managers are studying how social media are changing education, family life, shopping, and services such as medical care , financial advice, and political organizations. They are also dealing with issues of orgartizational impact, job redesign, distributed teamw ork, wo rk­ at-home scenarios, and long -term societal changes. As face-to-face interaction gives -vay to screen-to-screen, how can personal trust and organizational loyalty be preserved? How can empathy be conveyed and civic participation be enhanced?

Designers face the challenge of providing services on sma ll-, wall -, and mall ­ sized displays, ranging from jewelry, clothing (Fig. 1.6), smartphones, and tab ­ lets (Fig. 1.7) to large panels, projected displays, and illuminated buildings. When the plasticity of their designs provides smoo th conversion across different display sizes, consumers take pleasure; when conversions are difficult, consum ­ ers take notice. But the ma lleability of user interfaces has to extend to translation into multiple languages, accessibili ty support for users with disabilities, and accommodation for vary ing network bandw idths.

Some innovators promise that desktop compute rs and their user interfaces will disappear , as new interfaces become ubiquitous, pervasive, invisible, and embedded in the surrounding environment. They believe that novel devices will be context-aware, attentive, and perceptive, sensing users' needs and providing feedback through ambient displays that glow, hum, change shape, or blow air.

1.1 Introduction 31

FIGURE 1.6 Two children learn about the human body using a wearable , e-texti le shirt displaying real-time visualizations of how the body works via "organs" with embedded LED lights and sound (Norooz et al., 2015).

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32 Chapter 1 Usability of Interactive Systems

Designers are already offering interfaces that are wearable or control implanted (under-the-skin) devices, such as pacemakers, insulin pumps, and varied bio­ monitors. Other kinds of sensors already track FedEx packages, users entering buildings, or cars at tollbootl1s, but they will expand into elaborate sensor 11ets that follow crowds, epidemics, and pollution.

Other designers promote persuasive technologies that change users' behav­ ior, multi-modal or gestural interfaces that facilitate use, and affective interfaces that respond to the user's emotional state.

We are living in an exciting time for designers of user interfaces. The inspira­ tional pronouncements from technology prophets can be thrilling, but rapid progress is more likely to come from those who do the hard work of tuning designs to ge11uine human needs. These designers will rigorously evaluate actual use with eager early adopters, as well as reluctant late adopters, and seri­ ously study the resistant non-users. This book's authors believe that the next phase of human-computer interaction will be strongly influenced by those who are devoted to broadening the community of users by promoting universal usability and facilitating many forms of social media participation. User inter­ faces that deliver excellent user experiences will be a key component in improv ­ ing healthcare, creating sustainable economies, protecting natural resources, and resolving conflicts (Froeh lich et al., 2010; Friedman et al., 2014).

This first chap ter gives a broad overview of human-computer interaction from practitioners' and researchers' perspectives. It lays out usability goals, measures, and motivations in Sections 1.2 and 1.3 and closes with a statement of goals for our profession. Specific references cited in the chapter appear at the end, followed by a set of general references. Lists of relevant books, guidelines documents, journals, professional organizations, and video collections give readers starting points for further study.

The second chapter takes on universal usability, reminding readers of the opportunities to reach diverse users with tailored materials that serve the needs of young and old, high and low literac y users, diverse international users, and users with varying disabilities.

The third chapter reviews the guidelines, principles, and theories that -vill be drawn on and refined thr oughout the book. Chapters 4- 6 introduce design pro­ cesses and evaluation methods, with case study examples to demonstrate the processes and methods. Chapters 7-9 cover interaction styles that range from graphical direct manipulation to speech control and their implementation using common interaction devices . Collaboration is included in this part to emphasize the need for every designer to go beyond the personal comp uter and consider the many forms of social computing. Chapters 10-1 6 address the critical design decisions that often determine the success or failure of products and that may lead to breakthroughs that open the way to new possibilities. The Afterword reflects on the societal and individual impacts of technology.

1.2 Usability Goals and Measures 33

1.2 Usability Goals and Measures

Every designer wants to develop high-quality user experiences that are admired by colleagues, celebrated by users, and imitated by competitors. But getting such attention takes more than flamboyant promises and stylish advertising; it's earned by providing quality features such as usability, universality, and useful­ ness. These goals are achieved by thoughtful planning, sensitivity to user needs, devotion to requirements analysis, and diligent testing, all while keeping within budget and on schedu le.

Managers who pursue user-interface excellence first select experienced design ­ ers and then prepare realistic schedules that include time for requ iremerlts gather­ ing, guidelines preparation, and repeated testing. The designers begin by determining user needs, generating multiple design alternatives, and conducting extensive evaluations (Cllapters 4-6). Modem user-interface-building tools then enable implementers to quickly build working systems for further testing.

Successful designers go beyond vague notions of "user friendliness," "intui­ tive," and "natura l," doing more than simply making checklists of subjec tive guidelines. They llave a thorough u11derstanding of the diverse community of users and the tasks that must be accomplished. They study evidence-based guidelines and pursue the research literature when necessary. Great designers are deeply comm itted to enhancing the user exper ience, which strengthens their resolve when they face difficult choices, time pressures, and tight budgets. Great designers are also aware of the importance of eliciting emotional responses, attracting attention with animations, and playfully surpr isin g users.

When managers and designers have done their jobs well, their int erfaces gen­ erate positive feelings of success, compe tence, and mastery among users. The users have a clear mental model of the interface that enables them to confidently predict what will happen in response to their actions. In the best cases, the inter­ face almost disappears, enabling users to concentrate on their work, explora­ tion, or pleasure. This kind of calming environmen t gives users the feeling that they are "in the flow/' operating at their peak, while attaining their goals.

Close interaction with the user community leads to a well -chosen set of benchmark tasks that is the basis for usability goals and measures. For each user type and each task, precise measurable objectives guide the designer through the testing process. The ISO 9241 standard Ergonornics of Human-System Interac­ tion (ISO, 2013) focuses on admirab le goals-effectiveness, efficiene1;1 and satisfaction-but the following usability measures, which focus on the latter two goals, lead more directly to practical evaluation:

l. Ti1ne to learn. How long does it take for typical members of the user community to learn how to use the actions relevant to a set of tasks?

34 Chapter 1 Usability of Interactive Systems

2. Speed of perforniance. How long does it take to carry out the benchmark tasks?

3. Rate of errors by users. How many and what kinds of errors do people make in carrying out the benchmark tasks? Although time to make and correct errors might be incorporated into the speed of performance, error handling is such a critica l component of in terface usage that it deserves extensive study.

4. Retention over time. How well do users maintain their know ledge after an hour, a day, or a week? Retention may be linked closely to time to learn, and frequency of use plays an important role.

5. Subjective satisfaction. How much did users like using various aspects of the interface? The answer can be ascertained by interviews or by written sur­ veys that include satisfaction scales and space for free-form comments.

Every designer would like to succeed in e,rery measure, but there are often forced tradeoffs . If lengthy learning is permi tted, task-performance times may be reduced by use of abbreviations, hidden shortcuts, and compact designs that minimize scrolling. If the rate of errors is to be kept extremely low, speed of per ­ formance may ha, re to be sacrificed. In some applications, subjective satisfaction may be the key determinan t of success; in others, short learning times or rapid performance may be paramount. Project managers and designers who are aware of the tradeoffs can be more effective if they make their choices explicit and pub ­ lic. Requirements documents and marketing brochures that make clear whjch goals are pr imary are more likely to be va lued.

After multip le design alternatives have been raised, the leading possibi lities should be reviewed by designe rs and users . Low -fidelity paper mockups are useful, but high-fidelity interactive prototypes create a more realistic environ­ ment for expert reviews and usability testing. The user training and supporting materials such as online help can be produced before the implemen tation to provide another review and a new perspect ive on the design. Next, the imp le­ mentation can be carried out with proper software tools; this task should be a modest one if the design is complete and precise. Then, acceptance testing certi­ fies that the delivered interface mee ts the goals of the designers and customers. Final ly, continuous evaluation an d improvement have become common prac ­ tices. These design processes, evaluation procedures, and software tools are described more fully in Chapters 4-6.

The busiI1ess case for usability is strong and l1as been made repeated ly (Bias and Mayhew, 2005; Tullis and Albert, 2013). User-interface design success sto­ ries can also be managerial success stories for projects that are on budget and on schedule. A thoroughly documented set of user needs clarifies the design pro­ cess, and a carefully tested prototype generates fewer chai1ges durit1g implemen tation while avoiding costly updates after release. Thorough accep­ tance testing of the implementation produces robust interfaces that are aligned

1.3 Usabi lity Motivations 35

with user needs. Then continuous evaluation based on usage logs and user com­ ments guide evolutionary refinements.

1.3 Usability Motivations

The enormous interest in interface usability arises from the demonstration of the benefits that come from well-designed user interfaces. This increased motiva­ tion emanates from designers and managers of consumer electronics who pro ­ duce mobile devices, e-commerce websites, and social media where excellent user experiences are necessary to succeed in large, highly competit ive markets. Usability has gone from desirable to necessary for survival. Similarly, the huge interest in games and entertainment has raised the performance of devices, net­ works, and user interfaces. The goals are to ensure that game playing is fluid and vivid; that photo, music, and video streaming is fast; and that sharing is graceful and simp le. Strong motivations for usability quality come from high­ functioning professionals who demand excellence in environments such as life­ critical systems, industrial plants, legal offices, and police agencies. The spirit of usability excellence is also expected by users of exploratory, creative, and col­ laborative interfaces as well as diverse sociotechnical systems.

1.3. l Consumer electronics, e-commerce, and social media

User experience designers have played a key role in the dramatic growth of con­ sumer electronics by providing effective and satisfying designs that have become widely adopted for personal communications, education, healthcare, and much more. The annual Consumer Electronics Show, now replicated in many locations around the world, brings tens of thousands of exhib itors and hundreds of thousands of at tendees who are eager to try the latest products from leading vendors.

Produ ct announcements trigger worldwide media coverage, with Hollywood or sports personalities celebrating the newest products. Similarly, famed musi­ cians, supermodels, and other luminaries contribute to the media hype while making everyone aware of the latest designs, appealing features, and must-have capabilities. Heroes such as Apple's Chief Design Officer Jony Ive have become celebrities who are knighted by the Queen of England and pestered by inter­ viewers to reveal the secrets of the next product release.

The transformative power of consumer electronics has been celebrated by those who see improved family communication, better healthcare, thriving businesses, and wider access to education. The social media applications, domi­ nated by Facebook, and user-generated content such as online restaurant, film, or product reviews have become part of daily life for many users. For these

36 Chapter 1 Usability of Interactive Systems

interfaces, ease of learning, low error rates, and subjective satisfaction are para­ mount because use is discretionary and competition is fierce. If the users cannot succeed quickly, they will give up or try a competing supplier. Critics raise con­ cerns about reduced privacy, dangers in distracted dri ving, and declinit1g qua lity of interpersonal relationships.

1.3.2 Games and entertainment

The rapid expansion of home and entertainme11t applications is a further source of interest in usability. Personal-computing applications include e-mail clients, search engines, cellphones, digital cameras, and music players. Entertainment applications have flourished, making computer games a larger industry than Hollywood, while game input devices like the Nint endo ® Wii™ and the Microsoft Kinect's™ contro ller -free gameplay (Fig. 1.8) open up entirely new possibilities in areas ranging from sports to education to rehabilitation.

Choosing the right functionality -vhile keeping costs low is difficult. Novices are best served by a cons train ed , simp le set of actions, but as users' exper ience increases, so does their desire for more extensive functionality and rapid performance. A layered or leve l-structured design is one approach to facilitating graceful evolution from novice to expert usage: Users can move up to higher layers when they need additional features or have time to learn them. A simpl e

FIGURE 1.8 Dance Central, a highly successfu l dance-playing franchise of games in which users dance to popular songs and earn points for how well they keep up. The Dance Centra l website al lows users to purchase add iti onal songs and also hosts livestream events and community forums.

1.3 Usabi lity Motivations 37

example is the design of search engines, which almost always ha ve basic and advanced interfaces (Chapter 15). Another approach to winning novice users is to carefully trim the features to make a simple device or application so users can get star ted easily.

1.3.3 Professional environments

Most consum er electronics users a lso benefit from interfaces in professional environments from sup ermarkets to space sta tions . Life-critical systems include those that contro l air traffic, nuc lear reactors, power uti lities, police or fire dis ­ patch, mi litary operations, and clinical care (Fig. 1.9). In these applications, high costs are expected, but they should yield high reliability and effectiveness. Lengthy training periods are acceptable to obtain rapid, error-free performance, even when the users are under stress. Subjective satisfaction is less of an issue because the users are well-motivated professionals. Retention is obtained by fre­ quent use of common functions and practice sessions for emergency actions.

Typical industrial and commercial uses include interfaces for banking, insur-

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jective satisfaction is of modest importance; retention is obtained by frequent use. Speed of perfor­ mance is central for most of these

· applications because of the high volume of transactions, but opera ­ tor fatigue, stress, and burnout are legitimat e concerns. Trimming 10% off the mean transaction time could mean 10% fewer operators, 10% fewer workstations, and a 10% reduction in hardware costs.

38 Chapter 1 Usability of Interactive Systems

1.3.4 Exploratory, creative, and collaborative interfaces

An increasing fraction of computer use is dedicated to supporting open-ended . exploration that promotes human creativity while lowering barriers to collabo­ ration. Exploratory app lications include web browsers, search engines, data visualization, and team collaboration support. Creative applications include design environments (Fig. 1.10), music-composition tools, animation builders, and video-ed iting systems. Collaborative interfaces enable two or more people to work together (even if the users are separated by time and space) through use of text, vo ice, and video; through systems that facilitate face-to-face meetings; through large audience participation in webinars; or through sharing tools that enable remote collaborators to work concurrently on a document, map, calen­ dar, or image.

In these exploratory, creative, and collaborative environments, the users may be knowledgeable in the task domains but novices in the underlying computer con­ cepts. Their motivation is often high, but so are their expectations. Benchmark tasks are more difficult to describe because of the exploratory nature of these appli­ cations, and usage can range from occasional to frequent. In short, it is difficult to design and evaluate these systems. Designers can pursue the goal of having the

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1.3 Usability Motivations 39

computer "vanish" as users become completely absorbed in their task domains. This goal seems to be met most effectively when the computer provides a direct­ manipulation repre sentation of the world of action (Chapter 7), supplemented by keyboard shortcuts. Then tasks are carried out by rapid familiar selections or ges­ tures with immediate feedback and new sets of choices. Users can keep their focus on the task with minimal distraction caused by operating the interface.

1.3.5 Sociotechnical systems A growing domain for usability is in social systems that involve many people over long time periods, such as healthcare, citizen science, disa ster response, and community crime reporting. Int erfaces for these system s, often created by governmental organizations, have to deal with trust, privacy, and responsibility as well as limiting the harmful effects of malicious tampering, deception, and incorrect information. Users will want to know whom to turn to when things go wrong-and maybe whom to thank when things go right (Whitworth and de Moor, 2009).

For example, in electronic voting systems (Jones and Simons, 2012), citizens need to have reassuring feedback that their votes are correctly recorded, possi­ bly by having a printed receipt. In addition, government officials and profes­ sional observers from opposing parties need to have way s of verifying that the votes from each district and regional aggregations are correctly reported (Fig. 1.11). If complaints are registered, investigators need tools to review proce­ dures at every stage.

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On the left we see an examp le of a touchscreen voting kiosk interface (Summers et al., 2014). We see contest number 2 out of 10 and the five candidates. The selected candidate is clear ly marked. Some voting jurisdictions use paper ballots that are then digitized. The interface on the right allows rapid review of al l the handwritten marks. Courtesy of Clear Ballot (http://www.clearballot.com).

40 Chapter 1 Usability of Interactive Systems

Designers of sociotechnical systems have to take into consideration the diverse levels of expertise of users with different roles. Successful designs for the large number of novice and first-time users emphasize ease of learning and provide the feedback that builds trust. Desigt1S for professional administrators and seasoned investigators enable rapid performance of complex procedures, perhaps with visualization tools to spot unusual patterns or detect fraud in usage logs.

1 .4 Goals for Our Profession

Clear goals are usefttl not only for interface design but also for educational and professional enterprises. Three broad goals seem attainab le: (1) influencing aca­ demic and business researchers; (2) providing tools, techniques, and knowledge for commercial d.esigners; and (3) raising the user-interface consciousness of the general public.

1.4.1 Influencing academic and business researchers Researchers in human-computer interaction are prolific as they produce more than 10,000 papers per year. Their research include traditional controlled exper­ imentation in laboratory settings, but increasingly researchers conduct online testing with real users, ethnographic observations in users' homes or work ­ places, and long-term, in-depth case stud ies of users (Chapter 5).

Newer research methods include crowd-sourced user sh.tdies that invite thou ­ sands of users to participate or pay users through systems such as Amazon's Mechanical Turk. Another innovation is the use of user log data, observations, and interviews to provide complemen tary strategies that reveal actua l perfor­ mance in live settings. The combination of methods often leads to a deeper under­ standing of the ftmdamental principles of human interaction with computers.

The classic scientific method for interface research, which is based on con­ trolled experimentation, has this basic outline:

• Understanding of a practical problem and related theory

• Lucid statement of a testable hypothesis

• Manipulation of a small number of independent variables

• Measurement of specific dependent variabl es

• Careful selection and assignment of subjects

• Control for bias in subjects, procedures, and materials

• Application of statistical tests

• Interpretation of results, refinement of theory, and guidance for experimenters

1.4 Goals for Our Profession 41

Alhen experimental materials and methods are tested by pilot studies and results validated by replication in various situations, then the recommendations are more likely to be reliable.

Of course, the scientific method based on controlled experimentation has its weaknesses. It may be difficult or expensive to find adequate subjects, and labo­ ratory conditions may distort the situation so much that the conclusions have little value. Controlled experiments typically deal with short-term usage, so understanding long-term co11sumer behavior or experienced user strategies is difficult. Since controlled experiments emphasize statis tical aggregation, extremely good or poor performance by individuals may be overlooked. Fur­ thermore, anecdotal evidence or researcher insights may be given too little emphasis because of the authoritative influence of statistics.

Because of these concerns, researchers balance controlled experimentation with ethnographic observation methods and long-term, in-depth case studies. Anecdotal experierlces and subjective reactions are recorded, think-aloud approaches are employed, and field or case studi es can be carried out. Other research methods include crowd-sourced user studies, analysis of user logs, sur­ veys, focus groups, and interviews.

Within computer science and information studies, there is a growing aware­ ness of the need for greater atten tion to usability issues. Courses on human­ compu ter interaction are required for some undergraduate degrees, and interface design issues are being added to many curricula. Researchers who pro­ pose new programming languages, privacy -protection schemes, or network ser ­ vices are more aware of the need to align with human cognitive skills and preferences. Designers of advanced graphics systems, 3-D printing tools, or con­ sumer products increasingly recognize that their success depends on the con­ struction of effective user interfaces and creation of appealing user experiences.

There is a grand opportunity to apply the knowledge and techniques of tradi­ tional psychology (and of subfields such as cognitive and socia l psychology) to the study of human-computer interaction. Psychologists are investigating human problem solving and creativity with user interfaces to gain an under­ standing of cognitive processes and social dynamics. The benefit to psychology is great, but psycho logists also have a golden opportunity to dramatically influ­ ence an important and widely used technology. Similarly, sociologists and com­ munications theorists are now actively participating in human-computer interaction research.

Researchers in business, management, education, sociology, anthropology, and other disciplines are benefiting from and contributing to the study of human-computer interaction. There are many fruitful directions for research, but here are a few:

• Reduced anxiety and fear of computer usage. Although compu ters are widely used, some othen ,vise competent people resist using e-mail and engaging in e-commerce because they are anxious about-or even fearful of-breaking

42 Chapter 1 Usability of Interactive Systems

the device, making an embarrassing mistake, or having their pri,,acy vio­ lated. Fear of scams and frustration with e-mail spam could also be reduced by improved designs that promote security and privacy while increasing the users' control over their experiences.

• Graceful evolution. Although novices may begin their interactions with a computer by using just a few features, they may later wish to move up to more powerful facilities. Refined multi -layer interface designs, preference settings, and training materials are needed to smooth the transition from novice to knowledgeable user to expert. The differing requirements of novices and experts in terms of prompting, error messages, online assistance, display complexity, pacing, and informative feedback all need investigation . Users may be allowed to cus tomize their interfaces far beyond changing backgrounds, font sizes, and ring tones, but methods for guiding users through such processes are an open topic.

• Social niedia. The remarkable spread of social media is an indicator of larger changes to come. Enabling sharing of user-genera ted content, especially from mobile devices, is widespread; much work remains to be done in raising the quality of what is produced, enabling effective annotations, making these materials accessible, and facilitating reuse in ways that protect users' desires for privacy or profit.

• Input devices. The plethora of input devices presents opportuni ties and chal­ lenges to interface designers (Chapter 10). There are heated discussions abou t the relative merits of multi -touch screens, voice, gestures, and haptic feed ­ back. Such conflicts could be resolved through experimentatio n with multi ­ p le tasks and users. Under lying issues include speed, accuracy, fatigue, error correction, and subjective satisfaction.

• Information exploration. As navigation", browsing, and searching in multimedia digi tal libraries and the Wor ld Wide Web become more common, the pres­ sure for more effective strategies and tools has increased (Chapter 15). Users will want to filter, select, and restructure their information rapidly with mini­ mum effor t and withou t fear of getting lost or finding misleading informa tion. Large da tabases of text, images, graphics, sound, video, and scientific data, commonly called big data, are becoming easier to explore with information visualization and visual analytic tools.

1.4.2 Providing tools, techniques, and knowledge for commercial designers

User -interface design and deve lopment are hot topics, and international compe ­ tition is lively. Employers who used to see usability as a secondary topic are increas ingly hiring user exper ience designers, information architects, mob ile app implemen ters, and usabili ty testers . These employers recognize the

1.4 Goals for Our Profession 43

competitive advantage from high-quality consumer interfaces and from improv­ ing the performance of their employees. There is a great thirst for knowledge about software tools, design guidelines, and testing techniques. User-interface­ building tools provide suppor t for rapid prototyping and iI1terface development while aiding design consistency, supporting universal usability, and simplify­ ing evolutionary refinement.

Guidelines documents have been written for general and specific audiences (see the list at end of this chap ter). Most projects take the productive route of writing their own guidelines, which are tied to the problems of their application environments and users. These guidelines are constructed from experience with existing interfaces, research results, and knowledgeable guesswork.

lterati, re usability testing and expert reviews are appropriate during interface design. Once the initial iI1terface is available, contiI1uous refinements can be made on the basis of observations, surveys, interviews, usage log analysis, or more controlled empirical tests of novel strategies (Chapter 5). Agile processes emphasize lively design studi o critiqu es of proposals and rapid trials of multi­ ple alternatives to guide designers.

Feedback from users during the design process and for continuous refine­ ment can provide useful insights and guidance. E-mail, web -based tools, and text messaging allow users to send commen ts directly to the designers, while logs of user behaviors provide designers w ith further evidence of what needs fixing. While searchable databases of user questions can often resolve problems and guide designers, online user consultants and fellow users can provide assis ­ tance and supportive encouragement.

1.4.3 Raising the user-interface consciousness of the general public

The media are so filled with stories about user interfaces that raising public con­ sciousness of these tools may seem unnecessary . However, many people are still uncomfortable witl1 the technologies they use. When they use a bank machine, a cell phone, or e-mail, they may feel fearful of making mistakes, anxious about damaging the equipment, worried about feeling incompetent, or threatened by the computer "being smarter than I am." These fears are generated, in part, by poor designs tl1at have complex features, inconsistent terminology, confusing error messages, and tortuous sequences of actions.

One of our goals is to encourage users to translate their internal fears into outraged action. Instead of feeling guilty when they get a message such as DATA ERROR, users should express their anger at the user-interface designer who was so inconsiderate and thoughtless. Instead of feeling inadequate or fool­ ish because they cannot remember a complex sequence of actions, they shou ld compla in to the designer who did not provid .e a more conven ient mechanism or should seek another product that does.

44 Chapter 1 Usability of Int eractive Systems

Usabili ty ultimately becomes a question of national priorities. Advocates of electronic voting and other services and promoters of e-healthcare and e-leaming increasingly recognize the need to influence allocation of government resources and commercial research agendas. Policymakers and industry lead ers become heroes when they facilitate access and promote quality, but they become villains when failures threaten children, disrupt travel, or menace consumers.

As examples of successful and satisfying interfaces become more visible, the crude designs appear archaic and will become commercial failures. As design­ ers improve the user experience, some users' fears wi ll recede, and the positive experiences of their competence, mastery, and satisfaction will flow in.

Practitioner's Summary

When designers of interactive systems cond uct thorough u ser and task analyses, the y are more likely to gain insights that w ill lead them to a proper functional design. They are more likely to have positive outcomes if they pay attention to reliability, availability, security, integrity, standardi zation, portability, integrat ion, and the administrative issues of schedules and budgets. As d.esign alternatives are proposed, evaluations can lead to shorter learning times, more rapid task performance, lower error rates, easier retention, and higher user satisfaction. Designers who accommodate the needs of children, older adults, and users with disabilities can improve the quality for all users. As designs are refined and implemented, evaluation by pilot studies, expert reviews, usability tests, user observations, user log analysis, and acceptance tests can accelerate improvement. Success in product design is measured in terms of evidence that universal usability is being attained (rather than testimonials from a few enthu­ siastic users). The proliferating literature and evidence-based guidelines will be of assistance in designing projects while accommodating the increasingly diverse and growing community of users.

Researcher's Agenda

The criteria for success in research favor innovations that work for broad com­ munities of users performing useful tasks over longer time periods. At the same time, researchers are struggling to understand what kinds of imaginative con­ sum er products will attract, engage, and satisfy diverse populations. The oppor­ tun ities for researchers are unlimited. There are so many interesting, important, and doable projects that it may be hard to choose a direction. The goal of

Researcher's Agenda 45

universal usability through plasticity of interface designs will keep researchers busy for years. Getting past vague promises and measuring user performance with alternate interfaces will be central to rapid progress. Each study has two parents: the practical problems facing designers and the fundamental theories based on principles of human behavior and interface design. Begin by propos­ ing a lucid, testable hypothesis. Then consider the appropriate research meth­ odology, conduct the study, collect the data, and analyze the results. Each study also has three children: specific recommendations for the practical problem, refinements of theories, and guidance for future researchers.

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions.com / shneiderman

This book is accompanied by a website (www.pearsonglobaleditions.com/ shneiderman) that includes pointers to additional resources tied to the contents

of each chapter. In addition, this website contains information for instructors, stu­ dents, practitioners, and researchers. The links for Chapter 1 include pointers to

general resources on human-computer interaction, such as professional societies, government agencies, companies, bibliographies, and guidelines documents.

Readers seeking references to scientific journals and conferences can

consul t the online searchable bib liography for human-computer interaction (http://www.hcibib.org/). Maintained since 1989, unde r the heroic leadership of Gary Perlman, the HCI Bibliography makes available more than 120,000 journal, conference, and book abstracts plus link col lections on many top­

ics, including consulting companies, education, history, and international deve lopment.

Some wonderful World Wide Web resources are:

• Resource on usability methods and guide lines from the U.S. government: http://www.usability.gov/

• IBM's extensive guide to user -centered design methods: http://www. i bm .com/des ign/

• Interaction Design Foundation's free online educational materials: https://www.interaction-design.org/

• Diamond Bullet Design: http://www.usabilityfirst.com/

E-mai l lists for announcements and discussion lists are maintained by

ACM SIGCHI (http://www.acm.org/sigchi/) and by the British HCI Group (http:// www.bcs-hci.org.uk/), which also sponsors the frequently updated Usability

News (http://usabil itynews .bcs.o rg/) .

46 Chapter 1 Usability of Int eractive Systems

Discussion Questions

1. Devise an outline, consistent with the scientific method, which interface researchers should follow to validate their designs.

2. List some characteristics of successful user-interface designers with respect to the ir approach to solving UI problems.

3. As noted in this chapter, some skeptics feel that accommodating diversity requires dumbing-down or lowest-common-denominator strategies. However, the au thors claim that in their experience, rethinking interface designs to accommodate these di, rersity situations will result in a better product for all users. Give an example of a product that meets the specific needs of a certain group of people, yet gives all user s a better experience.

4. How can designers enco urage novice u sers to use a system?

5. Suggest three usability measures that can be direct ly used to produce a practical eval uatio11 of a sys tem . Keep the goals of efficiency and satisfactio11 in mind with these measures.

References

Specialized reference s for this chapter appear here; general information resour ces are listed in the following section.

Bias, Randolph and Mayh ew, Deborah (Editors), Cost-Justifi;ing Usability: An Update for the Internet Age, 2nd Edition, Morgan Kaufmann, San Francisco, CA (2005).

Center for Information Technolo gy Accommodation, Section 508: The road to accessibi l­ ity, Genera l Services Admi11is tration, Wa shin gton, DC (2015). Availab le at http:/ / www .section508.gov.

Friedman, C., Rubin, J., Brown, J., Buntin, M., Corn, M., Etheredge, L., Gunter , C., Musen, M., Platt, R., Stead, W., Sullivan, K., and Van Houweling, D., Toward a sci­ ence of learning sys tem s: A research agenda for the high -functioning learning health sys tem, Journal of the American Medical Informatics Association (2014), 1-6.

Froehlich, Jon, Findlater, Leah , and Landay , James, The d esign of eco-feedback technol­ ogy, Proceedings CHI 2010 Conference: on Human Factors in Con1puting Systems, ACM Press, New York (2010), 1999- 2008.

Jones, Doug las W., and Simons, Barbara, Broken Ballots: Will Your Vote Count? Center for the Study of Language and Information (2012).

Norooz, L., Mauriello, M., McNally, B., Jorgenson, A., and Froehlich, J., BodyVis: A new approach to body learning through wearable sensing and visualization , Proceed- ings CHI 2015 Conference: Human Factors in Cornputing Systen1s, ACM Press, New York (2015), 1025-1034.

References 47

Summers, K., Chisnell, D., Davies, D., Alton, N ., and McKeever, M., Making voting acces­ sib le: Designing digital ballot marking for peopl e with low literacy and mild cognitive disabilities. USENIX Journal of Election Technology and Systen1s (JETS) 2, 2 (2014).

Tu l lis, Thoma s, and Albert, William, Measuring the User Experience: Collecting, Analyzing, and Presenting Usability Metrics, 2nd Edition, Morgan Kaufmann (2013).

Whitworth, Brian and De Moor, Aldo (Editors), Handbook of Research on Socio-Technical Design and Social Networking Systen1s, IGI Global, Hers h ey, P A(2009).

General information resources Primary journals include the followin g:

ACM interactions: A Magazine for User interface Designers, ACM Press

ACM Transactions on Accessible Co111puting, ACM Press

ACM Transactions on Computer-Hu111an Interaction (TOCHI), ACM Press

AIS Transactions on Human-Co1nputer Interaction, AIS

Behaviour & Infonnation Technology (BIT), Taylor & Francis Ltd.

Con1puter Supported Cooperative Work, Springer

Hurnan-Con1puter Interaction, Taylor & Francis Ltd.

lnforn·1ation Visualization, Sage

Interacting with Co1nputers, Oxford Un iversity Press

International Journal of Hun1an-Computer Interaction, Taylor & Francis Ltd.

International Journal of Hun1an-Con1puter Studies, Elsevier

Journal of Usability Studies, User Experience Prof ess ional s Association

Universal Access in the Information Society, Spr in ge r

Other journal s that regularly carry articles of interest includ e:

ACM: Con·1munications of the ACM (CACM)

ACM Transactions on Graphics

ACM Transactions on Inforrnation Syste,ns

ACM Transactions on Interactive Intelligent Systen1s

ACM Transactions on the Web

Cognitive Science

Con1puters in Hun1an Behavior

Ergono1nics

Human Factors

IEEE Co,nputer

IEEE Con1puter Graphics and Applications

IEEE Transactions on Human-Machine Systems

IEEE Transactions on Visualization and Computer Graphics

Journal of Con1puter-Mediated Com111unication

Journal of Visual Languages and Cornputing

48 Chapter 1 Usability of Interactive Systems

Personal and Ubiquitous Cornputing

Presence

Psychnology

Technical Connnunication

User lvlodeling and User-Adapted Interaction

Virtual Reality

The Association for Computing Machinery (ACM) has a Special Interest Group on Com­ puter-Human Interaction (SIGCHI), which holds regularly scheduled conferences. ACM also publishes the highl y regarded Transactions on Hu1nan-Con1puter Interaction and the lively magazine interactions. Other ACM Special Interest Groups, such as Graphics and Interactive Techniques (SIGGRAPH), Accessible Computing (SIGACCESS), Multimedia (SIGMM), and Hypertext and the Web (SIGWEB), also produce conferences and nevvslet­ ters. Other relevant ACM groups are Computers and Society (SIGCAS), Design of Con,­ munication (SIGDOC), Groupware (SIGGROUP), Information Retrieval (SIGIR), and Mobility of Systems, Users, Data, and Computing (SIGMOBILE).

The IEEE Computer Society, through its many conferences, transactions, and maga­ zines, covers user-interface issues. Similarly, the business-oriented Association for Infor­ mation Systems (AIS) ha s a SIGHCI that publishes a journal and runs sessions at severa l conferences. The long-established Human Factors & Ergonomics Society also runs annual conferences and has a Computer Systems Technical Group with a ne,,v-sletter. Addition ­ ally, the Society for Technical Communications (STC), the American Institute of Graphic Arts (ATGA), the International Ergonom ics Association, and the Ergonomics Society iricreasingly focus on user interfaces . The influential business-oriented User Experience Professionals Association (UXP A) publishes the UX- User Experience magazine and the online Journal of Usability Studies. The UXPA also spawned the annual World Usability Day with hundreds of events around the world each Novembe r.

The International Federation for Information Processing has a Technical Commit­ tee (TC.13) and Working Groups on Human-Computer Interaction. The British Com­ puter Society Human -Computer Interaction Group has held an international conference since 1985. The French Association Francophone pour !'Interaction Homme -Machine (AFIHM), the Spanish Asociaci6n lnteracci6n Persona-Ordenador (AIPO), and othe r associations promote HCI within their language communities. Other groups conduct important events in South Africa, Australia/New Zealand, Scandinavia, Asia, Latin America, and elsewhere.

Conferences – such as the ones held by the ACM (especially SIGCHI), IEEE, Human Factors & Ergonomics Society, and IFIP-often have relevan t papers presented and pub­ lished in the proceedings . INTERACT, Human-Computer Interaction Internationa l, and Work with Computing Systems are conference series that cover user -interface issues broad ly. Many specia lized conferences may also be of interest: for examp le, User Inter ­ faces Software and Technology, Hypertext, Computer-Supported Cooperative Work, Intelligent User Interfaces, Computers and Accessibility, Ubiquitous Computing, Co1n­ puters and Cognition, Designing Interactive Systems, and more.

Brad Myers 's brief history of HCI (ACM Interactions, March 1998) is one starting point for those who want to study the emergence and evolution of this field. James Martin provided a thoughtful and useful survey of interactive systems in his 1973 book Design of Man-Camputer Dialogues. Ben Shneiderman's 1980 book Soft,vare PsychologtJ: Hun·1an Factors in Computer and Inforn1ation Systeins promoted the use of controlled experimenta l

References 49

teclmiques and scientific research methods. Rubinstein and Hersh's The Hun1an Factor: Designing Co,nputer Syste,ns for People (1984) offered an appealing introduction to com­ puter-system design and many useful guidelines. The first edition of this book, pub ­ lished in 1987, reviewed critical issues, offered guidelines for designers, and suggested research directions .

A steady flov.1 of influential books has stimulated widespread media and public atten ­ tion about usability issues, including Nielsen's Usability Engineering (1993), Landauer's The Trouble with Computers (1995), and Nielsen's Designing Web Usability (1999). Don Nor1nan's 1988 book The Psychology of Everyday Things (reprinted and revised in 2013 as The Design of Everyday Things) is a refreshing look at the psychological issues involved in the design of the everyday technology that surrounds us.

As the field matured, subgroups and publications centered around specia lized top­ ics emerged; this happened with mobile computing, web design, online communities, information visualization, virh1al environments, and so on. The following list of g1tide­ lines doc1tments and books is a startin g point to an exploration of the large and growing literature.

Guidelines documents Apple Computer, Inc., Hu,nan Interface Guidelines, Version for the Mac OS X, iPhone, iPad,

and Apple Watch, Apple, Cupertino, CA (April 2015). Available at http:// developer. apple.co m /.

-Exp lains how to design consistent visual and behavioral properties for Apple products.

International Organization for Standardization, ISO 9241 Ergonomics of Human-System Interaction, Geneva, Sv.1itzerland (updated 2013). Availab le at http://www.iso.org/ .

-Thorough genera l introduction, covering dialog principles, guidance on usabil­ ity, presentation of information, user guidance, menu dialogs, command dialogs, direct-manipulation dialogs, form -filling dialogs, and much more. This is an important source for many countries and companies.

Microsoft, Inc., The Microsoft Windoivs User Experience Interaction Guidelines, Redmond, WA (2015). Available at https:/ / msdn.microsoft.com/.

– Describes design principles, controls, text, interaction, windovvs, and aesthetics.

United Kingdom Health & Social Care Information Centre, User Interface Guidance Oune 2015). Available at http:/ /sys terns.hscic.gov .uk/ data/ cui/uig.

– Detailed guidelines oriented to medical systems.

United Kingdom Ministry of Defence, Hurnan Factors for Designers of Systen1s, De­ fence Standard 00-250 Oune 2013). Available at http:/ /vvww.dstan.mod.uk/ data /00/250 /00000100.pdf.

– Describes human factors, integration processes, requirements, and acceptance testing.

U.S. Dept. of Defense, Hun1an Engineering Design Criteria Standard, Military Standard MIL-STD-1472G, U.S. Government Printing Office, Washington, DC (2012).

-Covers traditional ergonomic and anthropometric issues. Later editions pay in­ creasing attention to user-computer interfaces. Interesting and thought-provoking reminder of many human-factors issues .

50 Chapter 1 Usab ility of Interactive Syste ms

U.S. Federal Aviation Administration, The Hun1an Factors Design Standard, Atlantic City, NJ (updated May 2012). Available at http://hf.tc.faa.gov/hfds/.

– Extensive compilation of human -factors standards for contractors to follow, espe ­ cially relevan t to aircraft and air-traffic control.

U.S. National Cancer Institute, Research-based Web Design and Usability Guidelines, Dept. of Health & Human Services, Nationa l Institutes of Health (2006, updated on the web 2015). Available at http://guidelines.usabi lity.gov/.

– Author ita tive and packed with numerous full-color examples of informat ion­ oriented websites.

World Wide Web Consortium's Web Accessibility Initiative, Web Content Accessibility Guidelines 2.0 (2008). Availab le at http://wv,;w.w3.org/WAI/.

-Practical, implementab le three-level pr ioritization of ,veb design gu ide lines for users with disabilities. The Web Accessibility Initiative (WAI) develops strategies, guidelines, and resources to help make the web accessible to people with dis­ abilities. Four principles are offered: Perceivable, Operable, Understandable, and Robust.

World Wide Web Consor tium, Web Accessibiliti; Evaluation Tools (2014). Available at http:/ /,vww.w3.org/WAI/ER/tools/.

– An occasionally updated list of software tools re lated to accessibility; demonstrates lively activity.

Books Allen, J., and Chudley, J., Snzashing UX Design: Foundations for Designing Online User

Experiences, Wiley, Chichester (2012).

Anderson, S., Seductive Interaction Design: Creating Plat;ful, Fun, and Effective User Experiences, New Riders (2011).

Barnum, Carol M., Usability Testing Essentials: Ready, Set … Test! Morgan Kaufmann (2011).

Baxter, Kathy, and Courage, Cathe rine, Understanding Your Users: A Practical Guide to User Requirements Methods, Tools, and Techniques, 2nd Edit ion, Morgan Kaufmann (2015).

Bell, Genevieve, and Dourish, Pau l, Divining a Digital Future: Mess and MythologtJ in Ubiquitous Conzputing, MIT Press (2011).

Berkman, Eric, and Hoobe r, Steven, Designing Mobile lnterfaces, O'Re illy, Sebastopol, CA (2011).

Boy, Guy, Handbook of Hun1an-Machine Interaction, Ashgate (2011).

Boy, Guy, Orchestrating Human-Centered Design, Springer (2013).

boyd, danah, It's Con1plicated: The Social Lives of Netlvorked Teens, Yale University Press (2014).

Buley, Leah, The User Experience Tean1 of One: A Research and Design Survival Guide, Rosenfeld Media (2013).

Cairns, P., and Cox, A. L. (Editors), Research Methods for Human-Computer Interaction, Camb ridge University Press (2008, reprinted 2011).

Refe rences 51

Calvo, Rafael A., and Peters, Dorian, Positive Conzputing: Technology for Wellbeing and Hunian Potential, MIT Press (2014).

Carroll, J. (Editor), Creativity and Rationale: Enhancing Human Experience by Design, Springer (2013).

Chandler, C., and Unger, R., A Project Design to UX Design: For User Experience Designers in the Field or in the Making, 2nd Edition, New Riders (2012).

Chandler, C ., and van Slee, A., Adventures in Experience Design, Ne"v Riders (2014)

Chapman, C., The Srnashing Idea Book: Frorn Inspiration to Application, Wiley (2011).

Colborne, Giles, Sin·zple and Usable Web, Mobile, and interaction Design (Voices That Matter), New Riders, Berkeley, CA (2011).

Cooper, A., Reimann, R., Cronin, D., and Noessel, C., About Face: The Essentials of Inte1face Design, 4th Edition, John Wiley & Sons (2104).

Crabtree, Andrew, Rouncefield, Mark, and Tolmie, Peter, Doing Design Ethnography, Springer, London (2012).

Craig, Alan B., Understanding Augrnented Reality: Concepts and Applications, Morgan Kaufmann, San Francisco, CA (2013).

Cunningham, Katie, Accessibility Handbook, O'Reilly Publishing (2012).

Dannen, Chris, iPhone Design Award-Winning Projects (The Definitive Guide), Apress, Berkeley, CA (2010).

Ferster, Bill, interactive Visualization: Insight through Inquiry, MIT Press (2012).

Garrett, J. J., The Elernents of User Experience: User-centered Design for the Web and Beyond, 2nd Edition, New Riders Press (2010).

Goodman, E., Kuniavsky, M ., and Moed, A ., Observing the User Experience, 2nd Edition, Morgan Kaufmann (2012).

Gothelf, J., and Seiden, J. (Editors), Lean UX: Applying Lean Principles to In1prove User Experience, O'Reilly Media (2013).

Greenberg, S., Carpendale, S., Marquardt, N., and Buxton, B., Sketching User Experiences: The Workbook, Morgan Kaufmann (2012).

Harris, D., Writing Hurnan Factors Research Papers: A Guidebook. Ashgate Publishing (2012).

Hartson, R., and Pyla, P., The UX Book: Process and Guidelines for Ensuring a Quality User Experience, Morgan Kaufmann (2012).

Hearst, Marti A., Search User Interfaces, Cambridge University Press, New York, NY (2009).

Hinman, Rachel, The Mobile Frontier: A Guide for Designing Mobile Experiences, Rosenfeld Media, Brooklyn, NY (2012).

Holtzblatt, Karen and Beyer, Hugh, Contextual Design Evolved, Morgan & Claypool (2014).

Horton, Sarah and Quesenbery, Whitney, A Web for Everyone: Designing Accessible User Experiences, Rosenfeld Media (2015).

Johnson, Jeff, Designing 1,vith the Mind in Mind: Sin1ple Guide to Understanding User lnteiface Design Rules, 2nd Edition, Morgan Kaufmann, San Francisco, CA (2014).

Jones, P., Design for Care: Innovating the Healthcare Experience, Rosenfe ld Media (2013).

52 Chapter 1 Usabi lity of Int eractive Systems

Katz, J., Designing Infor1nation: Hu1nan Factors and Corrnnon Sense in Inforn1ation Design. John Wiley (2012).

Kim, Gerard Jounghyun, Hurnan-Cornputer Interaction: Fundarnentals and Practice, CRC Press (2015).

Kipper, Greg, and Rampolla Jos ep h, A11gn1ented Reality: An Enzerging Technologies Guide to AR, Syngress (2012).

Klimczak, E., Design for Software, Wiley (2013).

Kolko, J., Thoughts on Interaction Design, 2nd Edition, Morgan Kaufmann (2011).

Koskinen , I., Zimmerman,)., Binder, T., Red strom, J., and Wensveen, S., Design Research through Practice fron1. the Lab, Field, and Showroorn, Morgan Kaufmann (2011).

Kraft, C., User Experience Innovation: User Centered Design That Works, Apress (2012).

Krug, Steve, Rocket Surgery Made Easy: The Do-it-yourself Guide to Finding and Fixing Usability Problerns, New Rider s (2010).

Krug, Steve, Don't Make Me Think, Revisited: A Co,nmon Sense Approach to Web Usability: 3r d Edition (Voices That Matter), New Riders, Berke ley, CA (2014) .

Lazar,)., Feng, J. H ., and Hochheiser, H., Research Methods in Human-Co-mputer Interac­ tion, Niley (2010).

Lazar, Jonathan, Goldstein, Daniel F., and Taylor, Anne, Ensuring Digital Accessibility through Process and Policy, Morgan Kaufmann (2015).

Levin, Michal, Designing Multi -Device Experiences: An Ecosysten1 Approach to User Experi­ ences across Devices, O'Reilly Media, Sebastopol, CA (2014).

Lund, A., User Experience Manage,nent: Essential Skills for Leading Effective UX Tearrzs, Morgan Kaufmann (2011).

MacKenzie, I. Scott, Hurnan-Cornputer Interaction: An Empirical Research Perspective, Mor ­ gan Kaufmann, San Fran cisco , CA (2013).

Mariani, Joseph, Rosset, Sophie, Garnier-Rizet, and Devi.Hers, Laurence (Editors), Natu­ ral Interaction with Robots, Knowbots and Smartphones: Putting Spoken Dialog Systen1s into Practice, Springer (2014).

McKay, E., UT ls Co1nn1unication: How to Design Intuitive, User-centered Interfaces by Focusing on Effective Co,nmunication, Morgan Kaufman11 (2013).

Moffett, Jack, Bridging UX and Web Develop1nent, Morgan Kaufmann (2014).

Monk, Andrew (Editor), Fundamentals of Hun1an-Con1puter Interaction, Morgan Kaufmann / Academi c Press (2014).

Nagel, Wolfram, Multiscreen UX Design: Developing for a lvfultitude of Devices, Morgan Kaufmann (2015).

Nakano, Y., Conati, C., Bader, T. (Edi tors), Eye Gaze in Intelligent User Interfaces: Gaze­ based Analyses, Models, and Applications, Springer (2013).

Nei l, Theresa, Mobile Design Pattern Gallery: UI Patterns for Smartphone Apps, 2nd Editio n, O'Reilly (2014).

Nie lsen, Jakob, and Perni ce, Kara, Eyetracking Web Usability, New Rid ers, Berkeley, CA (2010).

Nielsen, Jakob, and Budiu, Raluca, Mobile Llsability, New Riders, Berkele y, CA (2012).

Nielsen, Lene, Personas: User Focused Design, Springer, London (2013).

References 53

Norman, D., The Design of Everyday Things: Revised and Expanded Edition, Basic Books (2013).

Nudelman, G., Android Design Patterns, John Wiley (2013). Ava ilable at http: / /www .androiddesignbook.com.

Olson, J. S., and Kellogg, W. A. (Editors), Ways of Knowing in HCI, Springer (2014).

Oviatt, Sharon, and Cohen, Philip, The Paradign1 Shift to Multim.odality in Contemporary Con1puter Interfaces, Morgan & Claypoo l (2015).

Parush, Avi, Conceptual Design for Interactive Systen-zs: Designing for Perforn-zance and User Experience, Elsevier/Morgan Kaufmann (2015).

Pratt, A., and Nunes, J., Interactive Design: An Introduction. to the Theory and Application. of User-Centered Design., Rockport Publishers (2012).

Preece, J., Rogers, Y., and Sharp, H., Interaction Design: Beyond Human-Con1puter Interac­ tion, 4th Edition, Wiley, New York, NY (2015).

Purcha se, Helen, Experimental Hun1an-Con1puter Interaction: A Practical Guide with Visual Exa,nples, Cambr idge Universit y Press (2012).

Qu esenbery, vVhitney, and Szuc, Daniel, Global UX: Design and Research in a Connected World, Morgan Kaufmann (2011).

Redish, Janice, Letting Go of the Words: Writing Web Content That Works (Interactive Tech­ nologies), 2nd Edition, Morgan Kaufmann, San Franc isco, CA (2012).

Reiss, E., Usable Usabilih;: Sin1ple Steps for Making Stuff Better, Wiley (2012).

Ritter, Frank E., Baxter, Gordon D., and Churchill, Elizabeth F., Foundations for Design­ ing User-Centered Systems: What Syste111 Designers Need to Knoiv about People, Springer, London (2014).

Robinson, Simon, Jones, Matt, and Marsden, Gary, There's Not an App for That: Mobile User Experience Design for Life, Morgan Kaufmann (2015).

Salgado, L. C. C., Leitao, C. F., and de Souza, C. S., A Journey through Cultures: Metaphors for Guiding the Design of Cross-Cultural Interactive Systems, SpriJJger (2012).

Sauro, J., and Lewis, J., Quantifying the User Experience: Practical Statistics for User Research, Morgan Kaufmann (2012).

Schlatter, T., and Levinson, D., Visual Usability: Principles and Practices for Designing Digital Applications, Morgan Kaufinaru1 (2013).

Sharon, Tomer, It's Our Research: Getting Stakeholder Buy-in for Llser Experience Research Projects, Morgan Kaufmann (2012).

Stephanidis, Constantine, The Universal Access Handbook (Hurnan. Factors and Ergonon-zics), CRC Press, Boca Raton, FL (2009).

Tullis, Thomas, and Albert, William, Measuring the User Experience: Collecting, Analyzing, and Presenting UsabilihJ Metrics, 2nd Edition, Morgan Kaufmann (2013).

Weinschenk, S., 100 Things Every Designer Needs to Know about People, New Riders (2011).

Wigdor, Daniel, and Wixon, Dennis, Brave NUI World: Designing Natural User Interfaces for Touch and Gesture, Morgan Kaufmann, San Francisco, CA (2011).

Wilson, Chauncey, Brainstonning and Beyond: A User-Centered Design Method, Elsevier/ Morgan Kaufinaru1, Burlington (2013).

Wilson, Chauncey, IntervieuJ Techniques for UX Practitioners: A User-Centered Design Method, Elsev ier/Morgan Kaufmann, Burlington (2013).

54 Chapter 1 Usability of Interactive Systems

Wilson, Chauncey, User Interface Inspection Methods, Elsevier/Morgan Kaufmann, Amsterdam (2014).

Wilson, C. (Editor), User Experience Re-Mastered: Your Guide to Getting the Right Design, Morgan Kaufmann (2010).

Wilson, Max L., Search User Interface Design (Synthesis Lectures on Info1·n1ation Concepts, Retrieval, and Services), Morgan & Claypool Publishers, San Rafael, CA (2011).

Videos Video is an effective medium for presenting the dynamic, graphical, and interactive nature of modern user interfaces. A wonderhtl set of lech1res from Stanford University's CS547 Human-Computer Interaction Seminar can be found at http :/ /hci.s tanford.edu/ courses/ cs547 /.

Inspirational videos from the annual Technology, Entertainment & Design (TED) Con­ ference, which covers a wide range of topics including visionary user -interface themes, are found at http://w,.vw.ted.com/index.php/talks/. Another exceptional resource is YouTube (http:/ /www .youtube.com/), v,rhere a search on "user interfaces" produces a list of hundred s of recent product demonstrations, research reports, and some clever and funny technology demonstrations.

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CHAPTER

Usal1ilib>j

99 Social scientists have shown that teams and organizations whose members are heterogeneous in meaningfu l ways, for examp le, in

skill set, education, work experiences, perspectives on a problem, cultura l orientation, and so forth, have a higher potential for ''

innovation than teams whose members are homogeneous.

Beryl Nelson

Communications of the ACM, November 2014

99 I feel … an ardent desire to see knowledge so disseminated through

the mass of mankind that it may, at length, reach even the '' extremes of society: beggars and kings.

Thomas Jefferson

Reply to Ame rican Philosophical Society, 1808

CHAPTER OUTLINE 2.1 Introduction

2.2 Variations in Physical Abilities and Physical Workplaces

2.3 Diverse Cognitive and Perceptual Abilities

2.4 Personality Differences

2.5 2.6 2.7 2.8 2.9

Cultural and International Diversity

Users with Disabilities

Older Adult Users

Children

Accommodating Hardware and Software Diversity

57

58 Chapter 2 Universal Usability

2.1 Introduction

The remarkable div ers ity of hum an abil ities, background s, motivat ions , per­ sonalities, cultur es, and work styles challeng es int erface design ers. A youn g female designer in India ,..,ith computer training and a desire for rapid interac ­ tion using densel y packed displa ys may have a hard time designing a success ­ ful interf ace for older male arti sts in France with a more leisurely and free-form work style. Und ers tanding the phy sical, int ellectual , and personal ity differ­ ences among users is vital for expanding market share, supporting required government services, and enabling crea tive participa tion by the broades t possible set of users. As a profe ssion, we will be remembered for how well we meet our users' need s. That' s the ultimate goal: addre ssing the needs of all users (Fig. 2.1).

Raising the F1oor OH£.QZE -FIT8.0 NE DfQITAL IHa.US ION

wtio '" .,. Wlltt – do RHOUrtel Get lnvotwd News. PrttS cont.Kt us

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LATEST NEWS RtF people, Join us!

Tl'tl nslale to. .. 1:1 TEXT AND DISPLAY O RESET ALL

[B LAYOUT AND NAVl Tl N

l.'I LINKS AND BIITTONS

□ EMPHAS IZE LINKS Makes links larger, bold, and undertined

□ MAKE INPUTS LARGER Makes buttons, drop-down menus, texl-fiekls, and other inputs larger

Raising the Floor is an organization of diverse people from industry. academia, NGOs and other sectors who have c.ome together to ensure that people who face barriers due to disability, literacy, digital-literacy, and aging are able to fully understand, access, and use the digital world we are creating (the web, computers, tablets, phones, educational materials, ticket machines, thermostats, and even home appliances). Our central focus is the development of the Global Public Inclusive Infrastructure (GPII).

Benefits of RtF for …………

users service providers employers

FIGURE 2. 1 The website of Raising the Floor includes universa l accessibi lity features suc h as options fo r emphasizing the lin ks or making buttons large r, offering severa l font sizes, contrast , tex t desc riptio ns of photos, t ranslatio n services , and so on (http ://ww w . ra isi ngthef l oo r. net) .

2.2 Variations in Physical Abi lities and Physical Workplaces 59

The huge international consumer market in mobile de,,ices has raised the pressure for designs that are universally usable. While skeptics suggest that accommodating diversity requires dumbing-down or lowest-common­ denominator strategies, our experience is that rethinking interface designs for differing situations often resul ts in a better product for all users. Measures to accommodate the special needs of one group, such as curb cuts in sidewalks for wheelchair users, often have payoffs for many groups, such as parents with baby stroller s, skateboard riders, travelers with wheeled luggage, and delivery people with handcarts. With this in mind, this chapter introduces the challenges posed by physical, cognitive, perceptual, personality, and cultural differences. It covers considerations for users with disabilities, older adults, and young users, ending wi th a discussion of hardware and sof tware diver­ sity . The important issues of differerlt usage profiles (novice, intermittent, and expert), wide-ranging task profiles, and multiple interaction styles are covered in Chapter 3.

2.2 Variations in Physical Abilities and Physical Workplaces

Accommodating diverse human perceptual, cognitive, and motor abilities is a challenge to every designer. Fortunately, ergonomics researchers and practitio­ ners have gained substan tial experience from design projects with automobiles, aircraft, cellphones, and so on. This experience earl be applied to the design of user interfaces and mobile devices.

Basic data about human dimensions comes from research in anthropometry (Preedy, 2012). Thousands of measures of hundreds of features of peopl e- male and female, young and adult, European and Asian, underweight and over­ weight, tall and short – provide data to construct 5- to 95-percentile design ranges. Head, mouth, nose, neck, shoulder, chest, arm, hand, finger, leg, and foot sizes have been carefully catalog ed for a va riety of populations. The great diversity in these static measures reminds us that there can be no image of an "average" user and that compromises must be made or multiple versions of a system must be constructed.

Cellphone keypad design parameters – placement, size, distance between keys, and so forth (Section 10.2)-e vo lved to accommodate differences in users' physical abilities. People with especially large or smal l hands may have diffi­ culty using standard cellphones or keyboards, but a substantial fraction of the population is well served by one design. On the other hand, since screen­ brightness preferences vary substan tially , designers often enab le users to con­ trol this parameter. Similarly, controls for chair seat and back heights and for

60 Chapter 2 Universal Usability

disp lay angles allow individual adjustment. When a single design cannot accommodate a large fraction of the population, multiple versions or adjust­ ment controls are helpful.

Physical measures of static human dimensions are not enough. Measures of dynamic actions-such as reach distance while seated, speed of finger presses, or strength of lifting-are also necessary.

Since so much of work is related to perception, designers need to be aware of the ranges of human perceptual abilities, especially with regard to vision (Ware, 2012). For example, researchers consider human response time to varying visual stimuli or time to adapt to low or bright light. They examine human capacity to identify an object in context or to determine the velocity or direction of a moving point. The visual system responds differently to various colors, and some peo­ ple have color deficiencies, either permanently or temporarily (due to illness or medication). People's spectral range and sensitivity vary, and peripheral vision is quite different from the perception of images in the fovea (the central part of the retina). Designers need to study flicker, contrast, motion sensitivity, and depth perception as well as the impact of glare and visual fatigue. Finally, designers must consider the needs of people who wear corrective lenses, have visual impairments, or are blind.

Other senses are also important: for example, touch for keyboard or touch­ screen entry and hearing for audible cues, tones, and speech input or output (Chapter 10). Pain, temperature sensitivity, taste, and sme ll are rare ly used for input or output in interactive systems, but there is room for imaginative applications.

These physical abilities influence elements of the interactive-system design. They also play a prominent role in the design of the workplace or workstation (or p laystation). The Hurnan Factors Engineering of Con1puter Workstations stan ­ dard (HFES, 2007) lists these concerns:

• Worktable and display-support height

• Clearance under work surface for legs

• Work-surface width and depth

• Adjustabi]jty of heights and angles for chairs and work surfaces

• Posture-seating depth and angle, backrest height, and lumbar support

• Availability of armrests, footrests, and palmrests

• Use of chair casters

Workplace design is important in ensuring high job satisfaction, good performance, and low error rates. Incorrect table heights, uncomfortable chairs, or inadequate space to place documents can substantially impede work. The standards document also addresses such issues as illumination levels (200 to 500 lux); glare reductio11 (antiglare coatings, baffles, mesl1,

2.3 Diverse Cognitive and Perceptual Abilities 61

positioning); luminance balance and flicker; equipment reflectivity; acoustic noise and vibration; air temperature, movement, and humidity; and equipment temperature.

The most elegant screen design can be compromised by a noisy environ­ ment, poor lighting, or a stuffy room, and that compromise will eventually lower performance, raise error rates, and discourage even motivated users. Thoughtful designs, such as workstations that provide wheelchair access and good lighting, will be even more appreciated by users with disabilities and older adults.

Another physical-environment consideration involves room layout and the sociology of human interaction. With multiple workstations in a classroom or office, differer1t layouts can er1courage or limit social interaction, cooperative work, and assistar,ce with problems. Because users can often quickly help one another with minor problems, there may be an advantage to layouts that group several terminals close together or that enable supervisors or teachers to view all screens at once from behind. On the other hand, programmers, reser­ vations clerks, or artists may appreciate the quiet and privacy of their own workspaces.

Mobile devices are increasingly being used while walking or driving and in public spaces, such as restaurants or trains where lighting, noise, movement, and vibration are part of the user experience. Designing for these more fluid environments presents opportunities for design researchers and entrepreneurs.

2.3 Diverse Cognitive and Perceptual Abilities

A vital foundation for interactive-system designers is an understanding of the cognitive and perceptual abilities of the users (Radvansky and Ashcraft, 2013). The journal Ergonomics Abstracts offers this classification of human cognitive processes:

• Short-term and working memory

• Long-term and semantic memory

• Problem solving and reasoning

• Decision making and risk assessment

• Language communication and comprehension

• Search, imagery, and sensory memory

• Learning, skill development, knowledge acquisition, and concept attainment

62 Chapter 2 Universal Usability

It also suggests this set of factors affecting percep tual and motor performance:

• Arousal and vigilance

• Fatigue and sleep deprivation

• Perceptual (mental) load

• Knowledge of results and feedback

• Monotony and boredom

• Sensory deprivation

• Nutrition and diet

• Fear, anxiety, mood, and emotion

• Drugs, smoking, and alcohol

• Physiological rhythms

These vital issues are not discussed in depth in this book, but they have a pro­ found influence on the design of user interfaces. The term intelligence is not included in this list because its nature is controversial and measuring different forms of intelligence is difficult.

In any application, background experience and knowledge in the task and interface domains play key roles in learning and performance. Task- or computer­ skill inventories can be helpful in predicting performance.

2.4 Personality Differences

Some people are eager to use computers and mobile devices, while others find them frustrating. Even people who enjoy using these techno logies may have very different preferences for interaction styles, pace of interaction, graphics versus tabular presentations, dense versus sparse data presentation, and so on. A clear understanding of personality and cognitive styles can be helpful in designing interfaces for diverse communities of users.

One evident djfference is between men and women, but no clear pattern of gender -related preferences in interfaces has been documented. While the major­ ity of video -game players and designers are young males, some games (such as The Si1nsTM, Candy Crush Saga, and Farmville) draw ample numbers of female players. Designers can get into lively debates about why many women prefer certain games, often speculating that women prefer less violent action and quieter soundtracks. Other conjectures are that women prefer socia l games, characters with appealing personalities, softer color patterns, and a sense of closure and completeness. Can these informal conjectures be converted to measurable criteria and then validated?

2.5 Cultural and Internationa l Diversity 63

Turning from games to productivity tools, there is also a range of reactions to violent terms such as KILL a process or ABORT a program. These and other potentially unfortunate mismatches between the user interface and the users might be avoided by more thoughtful attention to individual differences among users.

Unfortunately, there is no siJnple taxonomy of user personality types. A popular, but controversial, technique is the Big Five Test, based on the OCEAN model (Wiggins, 1996): Openness to Experie11ce/lntellect (closed/ ope11), Consci­ entiousness (disorganized/organized), Extra version (introverted/ extraverted), Agreeableness (disagreeable/agreeable), and Neuroticism (calm/nervous). There are hundreds of other psychological scales, including risk taking versus risk avoidance; internal versus external locus of control; reflective versus unpulsive behavior; convergent versus divergent thinking; high versus low anxiety; tolerance for stress; tolerance for ambiguity, motivation, or compul ­ siveness; field dependence versus independence; assertive versus passive per­ sonality; and left- versus right-brain orientation. As designers explore comp ut er applications for the home, education, art, music, and enter tainm ent, they may benefit from paying greater attention to personality types. Consumer-oriented researchers are especially aware of the personality distinctions across market segments, so as to tune their advertising for niche products designed for tech­ savvy youngsters versus family-oriented parents.

Another approach to personality assessment is by studying user behavior. For example, some users file thousands of e-mails in a well -organized hierarchy of folders, while others keep them all in the inbox, using search strategies to find what they want later. These distinct approaches may well relate to personality var iables, giving designers the clear message that multiple requirements must be satisfied by their designs.

2.5 Cultural and International Diversity

Another perspective on individual differences has to do with cultural, ethnic, racial, or linguistic background (Quesenbery and Szuc, 2011; Marcus and Gould, 2012; Salgado, 2012). Users who were raised learning to read Japanese or Chi­ nese will scan a screen differently from users who were raised learning to read English or French. Users from reflective or traditional cultures may prefer inter­ faces with stable displays from which they select a single item, while users from action-orien ted or novelty-based cultures may prefer animated screens and multiple clicks. Preferred content of webpages also varies; for example, univer­ sity home pages in some cultures emphasize their impressive buildings and respected professors lecturing to students, while others highlight student team

64 Chapter 2 Universal Usability

projects and a lively social life. Mobile device preferences also vary across cul­ tures that lead to rapidly changing styles in successful apps, which may include playful designs, music, and game-like features.

More arld n1ore is being learned about computer users from different cultures, but user experience designers are still struggling to establish guidelines that are appropriate across multiple languages and cultu res (Sun, 2012; Pereira and Baranauskas, 2015). The growth of a worldwide computer and mobile device market means that designers must prepare for internationalization. Software architectures that facilitate customization of local versions of user interfaces offer a competitive advantage (Reinecke and Bernstein, 2013). For example, if all text (instructions, help, error messages, labels, and so on) is stored iI1 files, versions in other languages can be generated with little or no additional programming. Hardware issues include character sets, keyboards, and special input devices. User-interface design concerns for internationalization include the following:

• Characters, numerals, special characters, and diacriticals

• Left-to-right versus right-to-left versus vertical input and reading

• Date and time formats

• Numeric and currency formats

• Weights and measures

• Telephone numbers and addresses

• Names and titles (Mr., Ms., Mme., M., Dr.)

• Social Security, national identification, and passport numbers

• Capitalization and punctuation

• Sorting sequences

• Icons, buttons, and colors

• Pluralization, grammar, and spelling

• Etiquette, policies, tone, formality, and metaphors

The list is long and yet incomplete. Recent studies of consumer use show perfor ­ mance and preference differences for information density, animation, cute char­ acters, eagerness for timely updates, incentives for social participation, and game-like features. Whereas early designers were often excused from cultural and linguistic slips, the current highly competitive atmosphere means that more effective localization may produce a strong advantage. To develop effective designs, companies run usability studies with users from different coU11tries, cultures, and language communities.

The role of information technology in intematio11al development is steadily growing, but much needs to be done to accommodate the diverse needs of users

2.5 Cultural and Inte rnationa l Diversity 65

wi th vas tly different language skills and technology access. To promote interna­ tional efforts to foster successful implementation of information technologies, representatives from around the world meet regularly for the United Nations World Summit ort the Information Society. They declared their

desire and commitm ent to build a people -centered, inclusive and deve lopmen t­ or iented Information Society, where everyone can create, access, utilize and share information and knowledge, enabling individuals, communities and peoples to achieve their full potential in promoting their sustainable develop­ ment and improving their quality of life, premised on the purposes and prin­ ciples of the Charter of the United Nations and respecting fully and upholding the Unive rsal Declaration of Human Rights.

The plan calls for applications to be "accessible to all, affordable, adapted to local needs in languages and culture, and [to] support sustainable develop­ ment." The UN Sustainability Development Goals include erad icate extreme poverty and hunger; reduce child mortality; combat HIV/AIDS, malaria, and other diseases; and ensure environmental sustainab ility. Information and com­ mU11ications technologies can play important roles in developing the infrastruc ­ ture that is needed to achieve these goals (Fig. 2.2).

FIGURE 2.2 Designing for cellphones can open the door to a wider audien ce (Medh i et al., 2011 ), for example, in developing countries where feature phones often are the only way to access the internet, literacy may be an issue, and users have very low monthly limits on the data volume they can use.

66 Chapter 2 Universal Usability

2.6 Users with Disabilities

When digital content and services can be flexibly presented in different formats, all users benefit (Horton and Quesenbery, 2014). However, flexibility is most appreciated by users witl, disabilities who now can access content and services using diverse input and output devices. Blind users may utilize screen readers (speech output such as JAWS or Apple's VoiceOver) or refreshable braille dis­ plays, while low-vision users may use magnification. Users with hearing impair­ ments may need captioning on videos and trru,scripts of audio, and people witl, limited dexterity or other motor impairments may utilize speech recognition, eye-tracking, or alternative keyboards or pointing devices (Fig. 2.3). Increas­ ingly, especially on Apple products, iliese alternate forms of input or output are integrated into technology out of the box (other laptops, tablets, ru,d smart­ phones have add-on screen reader and magnification capability, and a small number of laptops have built -in eye tracking).

There is a long history of research on how users with perceptua l or motor impairments (such as iliose described above) interact with technology, and research on intellectual or cognitive impairments is now also increasing (Blanck, 2014; Chourasia et al., 2014). In some cases, people wiili intellectual impairments

FIGURE 2.3

A young man uses a wheelc hair-moun ted augmentative communication and contro l device to control a standard television. New universal remo te console standards can allow people to use communication aids and other personal electronics as alternate interfaces for digital electronics in their environments (http://trace.wisc.edu ).

2.6 Users with Disabilities 67

need transformation of content, but in other cases, no modifications or assistive technologies are needed. Designing for accessibility helps everyone. The same captioning on video that is utilized by users with hearing impairments is also used by users watching video in noisy locations, such as gyms, bars, and airpor ts. Many accessibility features help with graceful presentation of content in multiple formats, allowing for flexibility in presentation on small screens of mobile devices or with audio output instead of visual output. As users are increasingly on the go and experience "situational impairments," these accessibility features help all users, who may be in situations where they canno t see their screen (e.g., they are driving a car) or cannot play audio out loud (e.g., on a plane).

For interfaces to be accessible for people with disabilities, they generally need to follow a set of design guidelines for accessibility. The ir,ternational standard s for accessibility come from the Web Accessibility Initiative, a project of the World Wide Web Consortium. The best-known standards are the Web Content Accessibility Guidelines (WCAG); the current version is WCAG 2.0 (since 2008, http:/ /www .w3.org /TR/WCAG20/). There are also other guidelines such as the Authoring Tool Accessibility Guidelines (ATAG) for developer tools and the User Agent Accessibility Guidelines (UAAG) for browsers. Other guidelines, such as EPUB3, exist for ebooks. Because WCAG 2.0 is the best -known, best­ understood, and most-documented set of accessibility guidelines in the wor ld, there is a companion guide, known as Guidance on Applying WCAG 2.0 to Non-Web Information and Communications Technologies (WCAG21CT), for utilizing WCAG concepts in non -vveb technologies (Cunningham, 2012).

These concepts of digital accessibility are not new. The first version of WCAG came out in 1999, and cap tioning of video has existed for more than 30 years. The accessibi lity features are not technica lly hard to accomp lish. WCAG requires, for instance, that all graphics have ALT text describing the image, that a webpage not have flashing that could trigger seizures, that tables and forms be marked up with appropriate labels (such as first name, last name, street address instead of FIELDl, FIELD2, FIELD3) to allow for identification. Another WCAG requirement is that all content on a page can be accessed even if you cannot use a pointing device through keyboard access. Creating accessible digital content is simply good coding, and it doesn't change, in any way, how informatio n is visual ly presented.

Similar concepts apply for creating accessible word-processing documents, presentations, and PDF files-appropriate labeling and descriptions ensure that a document or presentation will be accessible . Multiple approaches for accom­ plishing a task allow for successfu l task completion for a diverse population of users. Even when properly utilizing guidelines such as WCAG 2.0, it is a good idea to evaluate for success by usability testing with people with disabilities, expert reviews, and automated accessibility testing.

The Web Content Accessibility Guidelines form the basis for many of the laws and regulations around the world. Section 508 of the Rehabilitation Act in

68 Chapter 2 Universal Usability

the United States requires that when the federal government develops, pro­ cures, maintains, or uses electronic and information technology, that technology must be accessible for employees and members of the general public who have disabilities. This applies to procurement of both l-1ardware and software technol­ ogy as well as ensuring that websites are accessible (Lazar and Hochheiser, 2013; Lazar et al., 2015).

The Americans with Disabilities Act, as interpreted by federal courts and the U.S. Department of Justice, also reqt1ires accessibility of state and local govern­ ment websites as well as those of private companies and organizations that are considered "public accommodations" (stores, museums, hotels, video rental, etc.). The U.S. Department of Justice is also enforcing accessibility of websites and instructional materials at universities. Lawsuits such as those against Tar­ get, Netflix, Harvard University, and MIT highlight the increasing importance and expectations of digital accessibility.

The European Union Mandate 376 (http:/ /www.mandate376.eu/) will reqt1ire procurement and de, relopment of accessible technologies by EU gov­ ernments and will coordinate with U .S. Section 508, utilizing WCAG 2.0 and enabling developers to easily satisfy both U.S. and EU legal requirements. Prior to EU Mandate 376, many European countries, such as the UK, Italy, and Germany, and other countries around the world, including Australia and Canada, also had information technology accessibility requirements. The cov­ erage (only government technology or also public accommodations), required reporting requirements, and penalties for noncompliance differ from country to country.

The United Nations Convention on the Rights of Persons with Disabilities (CRPD, http:/ /wvvw .un.org / disabilities/ convention/ conventionfull.shtml), an international human rights agreement, also addresses accessible technology. Article 9 of the CRPD calls upon countries to "Promote access for persons with disabilities to new information and communications technologies and systems, including the Internet,'' and article 21 encourages countries to "[provide] infor­ mation intended for the general public to persons with disabilities in accessible formats and technologies appropriate to different kinds of disabilities."

Accessibility is a core feature of contemporary information systems, baked into development from the start. Programmers who follow coding standards and guidance from WCAG 2.0 add minimal cost in development ye t provide valuable services to all users. By contrast, implementers wl10 seek to retrofit for accessibility find that their effort is much greater (Wentz et al., 2011).

Increasingly, a person's economic success depends on equal access to digi­ tal content and services. University classes take place online, job postings are made online, and job applications must be submitted online. Prices are often lo,ver when using a company website instead of calling the company on the phone. When people wi th disabilities l,ave equal access to digital conten t and services, they have access to the full ra11ge of economic opportunities. The

2 .7 Older Adu lt Users 69

good news is that computer scientists, software engineers, developers, design­ ers, and user experience professionals have the opportunity, through good design, appropriate coding standards, and proper testing and evaluation, to ensure equal access.

2.7 Older Adult Users

Seniority offers many pleasures and all the benefits of experience, but aging can also have negative physical, cognitive, and social consequences. Understanding the human factors of aging can help designers to create user interfaces that facil­ itate access by older adult users (Fig. 2.4). The benefits include improved chances for productive employment and opportunities to use writing, e-mail, and other computer tools plus the satisfactions of education, entertainment, social interac­ tion, and challenge (Newell, 2011; Czaja and Lee, 2012) . Older adults are partic­ ularly active participants in health support groups. The benefits to society include increased access to older adults, which is valuable for their experience and tl1e emotional support they can provide to others.

F GURE 2. HomeAssist is an assisted liv ing platform for older adu lts installed in homes is Bordeaux, France. The tablet is used to show alerts (e.g ., when t he front doo r was left opened) and rem inders but also to run a slide show of photog raphs when not in use ( http ://phoe nix.in ri a. fr/resea rch-pro jects/ homeassist) .

70 Chapter 2 Universal Usability

The National Research Council 's report Human Factors Research Needs for an Aging Population describes aging as

a nonuniform set of progressive changes in physiological and psychological functionin g …. Average visual and auditory acuity decline considerably with age, as do average strength and speed of response … . [People experience] loss of at least some kind s of memory function, declines in perceptual flex­ ibility, slo,,ving of "stimulus encoding," and increased difficulty in the acquis ition of comp lex mental skills, … visual functions such as static visua l acuity, dark adaptation, accommodation, contras t sens itivity, and per iph eral vision decline, on average, with age. (Czaja, 1990)

This list has its di scouraging side, especially since older adults ma y have multiple impairments, but many older adults increasingly experience only moderate effects, allowing them to be active participants, even throughout tl1eir ninetie s .

The further good news is that interface designers can do much to accommo­ date older adult users (Chisnell et al., 2006). Improved user experiences give older adults access to the beneficial aspects of computing and network communication, thu s bringing man y societal advantages. How many young peop le's lives might be enriched by e-mail access to grandparents or great-grandparents? How many businesses might benefit from electronic consultations with experienced older adults? How many government agencies, universities, medical centers, or law firms could advance their goals from easily available contact with knowl edge­ able, older adult citizens? As a socie ty, how might we all benefit from the contin ­ ued creative work of older adults in literature, art, music, science, or philosophy?

As the world's population ages, designers in many fields are adapting their work to serve older adults, which can benefit all users. Baby boom ers have already begun to pu sh for larger street signs, brighter traffic lights, and better nighttim e lighting to make driving safer for drivers and pedestrians. Similarly, desktop, web, and mobile devices can be improved for all users by providin g users with control over font sizes, display contrast, and audio levels. Interfaces can also be designed with easier­ to-use pointing devices, clearer navigation path s, and consistent layout s to impro ve access for older adults and every user (Hart et al., 2008; Czaja and Lee, 2012).

Considering older and disabled users during the design process often pro ­ duces novel designs (Newell, 2011), such as ballpoint pens (for people with impair ed dexterity), cassette tape recorders (for blind users to listen to audio­ books), and auto-completion software (to reduce keystrokes). Texting interfaces that suggest words or web-address comp letion were originally designed to ease data input for older and disabled us ers but have become expec ted conveniences or all users of mobile devices and web brow sers. These conveniences, which reduce cognitive load, percep tual difficu lty, and motor control demands, become vital in difficult environments, such as while traveling, injured, stressed, or under pressure for rapid correct completion. Similarly, subtitles (closed

2.8 Children 71

captioning) and user-controlled font sizes were designed for users with hearing and visual difficulties, but they benefit many users.

Researchers and designers are actively working on improving interfaces for older adults (Czaja and Lee, 2012). In the United States, the AARP's Older Wiser Wired initiatives provide education for older adults and guidance for designers. The European Union also has multiple initiatives and research support for com­ puting for older adults.

Networking projects, such as the San Francisco-based SeniorNet, are provid­ ing adults over the age of 50 with access to and education about computing and the Internet "to enhance their lives and enable them to share their knowledge and wisdom" (http:/ /www.seniomet.org/). Computer games are attractive for older adults, as shown by the surprising success of Nintendo's Wii, because they stimulate social interaction, provide practice in sensorimotor skills such as eye­ to-hand coordination, enhance dexterity, and improve reaction time. In addi­ tion, meeting a challenge and gaining a sense of accomplishment and mastery are helpful in improving self-image for anyone.

In our experiences in bringing computing to two residences for older adults, we also encountered residents' fear of computers and belief that they were incapable of using computers. These fears gave way quickly after a few positive experiences. The older adu lts, who explored e-mail, photo sharing, and educational games, felt quite satisfied with themselves and were eager to learn more. Their newfound enthusiasm encouraged them to try automated bank machines and supermarket touchscreen kiosks. Suggestions for redesigns to meet the needs of older adults (and possibly other users) also emerged – for example, the appeal of high-precision touchscreens compared with the mouse was highlighted (Chapter 10).

In summary, making computing more attractive and accessible to older adults enables them to take advantage of technology, enables others to benefit from their participation, and can make technology easier for everyone. For more information on this topic, check out the Human Factors & Ergonomics Society (http:/ /www.hfes.org), which has an Aging Technical Group that publishes a newsletter and organizes sessions at conferences.

2.8 Children

Another lively community of users is children, whose uses emphasize entertain­ ment and education (Hourcade, 2015). Even pre-readers can use computer­ controlled toys, music generators, and art tools. As they mature, begin reading, and gain limited keyboard skills, they can use a wider array of desktop applications, web services, and mobile devices (Foss and Druin, 2014). When they become teenagers, they may become highly proficient users who often help their parents or other adults. This idealized growth path is followed by many

72 Chapter 2 Universal Usability

children who have easy access to technology and supportive parents and peers. However, many children without financial resources or supportive learning environments struggle to gain access to technology. They are often frustrated with its use and are endangered by threats surroUI,ding privacy, alienation, por­ nography, unhelpful peers, and malevolent strangers.

The noble aspirations of designers of children's software include educational acceleration, facilitating socialization with peers, and fostering the self-confidence that comes from skill mastery (Fig. 2.5). Advocates of educational games promote intrinsic motivation and constructive activities as goals, but opponents often complain about the harmful effects of antisocial and violent games.

For teenagers, the opportunities for empowerment are substantial. They often take the lead in emp loying new modes of communication, such as text messag­ ing on cellphones, and in creating cultura l or fashion trends tl,at surprise eve11 the designers (for example, playing with simulations and fantasy games and participating in web-based virtual worlds).

Appropriate design principles for childr en's software recognize young peo­ ple's intense desire for the kind of interactive engagement that gives them con­ trol with appropriat e feedback and supports their social engagement with peers (Bruckman et al., 2012; Fails et al., 2014). Designers also have to find the balance between children's desire for challenge and parents' requirements for safety.

Children can deal w ith some frustra tions and with threatening stories, but they also want to know that they can clear the screen, start over, and try again without severe penalties. They don't easily tolerate patronizing comments or

FIGURE 2.5

._., …. •••

•

—–.. –

–'GI'

Using Digita l Mysteries on a tablet, two elementary school children work together to read information slips, group them, and create a sequence to answer the quest ion "Who killed King Ted?" The blue pop-up pie menu allows the selection of tools. A larger tabletop version allows larger groups to collaborate (http ://w ww. reflectiveth inking .com).

2.8 Children 73

inappropriate humor, but they like familiar characters, exploratory environ­ ments, and the capacity for repetition. Younger children will sometimes replay a game, reread a story, or replay a music sequence dozens of times, even after adul ts have tired of it. While too mucl-1 "screen time " can interfere wi th cl-1ild­ hood development, well-designed applications can help children with physical, relationship, and emotional problems (Borjesson et al., 2015).

Some designers work by observing children and testing software with chil­ dre11, while the innovative approach of "children as our technology-des ign part­ ners" engages them in a long -term process of cooperative inquiry during which children and adults jointly design novel products and services. A notable suc­ cessful product of working with children as design partners is the International Children's Digital Library, which offers 4500-plus of the world's best children's books it1 SO-plus languages using an interface in 19 languages while supporting low-and high -speed networks.

Designing for younger children requires attention to their limitations. Their evo lving dexterity means that mo11se dragging, double-clicking, and sma ll tar­ gets cannot always be 11sed; their emerging literacy means that wri tten instruc­ tions and error messa ges are not effective; and their low capacity for abstractio n means that complex sequences must be avoided unless an adult is involved. Other concerns are short at tention spans and limited capaci ty to work with mul ­ tiple concep ts simul taneously . Designers of children's software also have a responsibi lity to attend to dangers, especially in web -based environments, where parental control over access to violent, racist, or pornographic materials is unfortunately necessary. Appropriate information for the education of chil­ dren about privacy issues and threats from strang ers is also a requirement.

The capacity for playful creativity in art, music, and writing and the value of educational activities in science and math remain potent reasons to pursue chil­ dren's software. Enabling them to make high-quality images, photos, songs, or poems and then share them with friends and family can accelera te childr en' s personal and social development. Offering access to educa tional materials from libraries, museums, government agencies, schools, and commerc ial sources enriches their learning experiences and serves as a basis for children to construct their own web resources, participate in collaborative efforts, and contribut e to community-service projects.

Providing programming tools, such as the Scratch project (https:/ /sc ratch. mit.edu/), and simulation-building tools enables older children to take on com­ plex cognitive challenges and construct ambitious artifacts for others to use. These and other opportunities have motivated efforts (such as One Laptop Per Child, http:/ /one .laptop.org/) to bring low-cost computers to children around the world. Advocates point to enthusiastic adoption and tell stories of it1divid­ ual enablement. However, critics encourage a shift from the technology-centered goals to greater attention to rich content, social engagemen t, parental guidance materials, and effective teacher training.

74 Chapter 2 Universal Usability

2.9 Accommodating Hardware and Software Diversity

In addition to accommodating different classes of users and skill levels, design­ ers need to support a wide range of hardware and software platforms. The rapid progress of technology means that newer systems may have a hundred or a thousand times greater storage capacity, faster processors, and higher­ bandwidth networks. However, designers need to accommoda te older devices and deal with newer mobile devices that may have low-bandwidth connections and small screens (Fig. 2.2).

The challenge of accommodating diverse hardware is coupled with the need to ensure access through many generations of software. New operating systems, web browsers, e-mail clients, and application programs should provide back­ ward compatibility in terms of their user -interface design and file structures. Skeptics will say that this requirement can slow innovation, but designers who plan ahead carefully to support flexible interfaces and self-defining files will be rewarded with larger market shares .

For at least the next decade, three of the main technical challenges wi ll be:

• Producing satisfying and effective Internet interaction on high-speed (broad­ band) and slower (dial-up and som.e wireless) connections. Some techn ologi­ cal breakthroughs ha ve already been made in compression algorithms to reduce file sizes for images, music, animations, and even video, but more are needed. New technologies are needed to enable pre-fetching or sched­ uled downloads. User con trol of the amount of material downloaded for each request could also prove benefici al (for example, allowing users to specify that a lar ge image should be reduced to a smaller size, sent with fewer colors, converted to a simplified line drawing, replaced with just a text description, or downloaded at night when Internet charges are perhaps lower).

• Responsive design enabling access to web services from large displays (3200 x 2400 pixels or larger) and smaller mobile devices (1024 x 768 pixels and s1rialler). Rev.rrit­ ing each webpage for different display sizes may produce the best quality, but this approach is probably too costly and time-consuming for most web providers. Software tools such as Cascading Style Sheets (CSS) allow design­ ers to specify their content in a way that enables automatic conversions for an increasing range of display sizes.

• Supporting easy n1aintenance of or automatic conversion to 1r1ultiple languages. Commercial operators recognize that they can expand their markets if they can pr ovide access in multipl e langua ges and across multiple countri es. This means isolating text to allow easy substitution, choosing appropriate

Researcher's Agenda 75

metaphors and colors, and addressing the needs of diverse cultures (Section 2.5).

Practitioner's Summary

The good news is that when designers think carefully about the needs of diverse users, they are like ly to come up wi th desktop, laptop, web, and mobile device designs that are better for all users. A frequent path to success is through par­ ticipatory methods that bring designers in close and continuing contact with their intended users. In some cases, improved tools and designs mean that one design can be made so flexible that it can be presented automatical ly in text (with a wide range of font sizes, colors, and contrast ratios ), in speech (with male or female styles and at varying volumes and speeds), and in a wide range of display sizes. Adjustments for different cuJtures, personalities, disabilities, ages, input devices, and preferences may take more design effor t, bt1t the pay­ offs are in larger markets and more satisfied users. As for costs, with appro­ priate software tools, e-commerce providers are finding that a small additiona l effort can expand markets by 20% or more. Although it can require additional effort, designing for diverse users is cost effective and sometimes leads to major breakthroughs.

Researcher's Agenda

While market forces provide incentives for changes, additional legal and policy interventions could speed progress in ensuring that desktop, laptop, web, and mobile device user iI1terfaces continue to be accessib le to all . The expanding worldwide research community, especially the ACM Special Interest Group on Accessible Computing (SIGACCESS), hosts international conferences, publishes journals, and encourages further research.

Research on diversity often brings innovations for all users; for example, input devices for users wi th poor motor control can often help all passengers in rough riding cars, buses, trains, or planes. Impro ved automated assistance for conversions to diverse languages and cuJtures would improve designer produc­ tivity and facilitate changes to prices, dimensions, colors, and so on. Research on cultural diversity is still needed about the acceptability by differing user groups of novel features like emoticons, animation, personalization, gamification, and musical accompaniments.

76 Chapter 2 Universal Usability

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions . com / shneiderman

Major suppliers offer diverse accessibi lity too ls:

• Apple: https://www.apple.com/accessibility/

• Microsoft: http://www .microsoft.com/enable/ • Google: https:/lwww.google.com/accessibility/

And many consumer-oriented and government groups provide assistance, such as:

• AARP : http://www.aarp.org/home-family/personal-technology/ • Older Adults Technology Services: http://oats .org/ • U.S. Section 508: http://www.section508.gov/ • Resource list from Trace Center: http://trace.wisc.edu/resources/

Discussion Questions

1. Describe three populations of users with special needs. For each of these pop ­ ulations, suggest three ways current interfaces could be improved to better serve them.

2. Suppose you need to design a system for users in two countries that are very different from each other culturally. What are some of the design concerns that you should be aware of to create a successful design?

3. In certain interfaces, it is necessary to inform users of an abnormal condition or time-dependent information. It is important that the display of this infor­ mation catches the user's attention. Suggest five ways a designer can success­ fully attract attention.

4. Name a piece of software you often use where it is easy to produce an error. Explain ways you could improve the interface to better prevent errors.

5. What factors should designers co11sider to address the needs of individuals with different physical abilities?

References

Blanck, P., eQuality: The Struggle for Web Accessibility by Persons with Cognitive Disabilities, Cambridge University Press (2014).

References 77

Borjesson, P., Barendregt, W., Eriksson, E., and Torgersson, 0 ., Designing technology for and with developmentally diverse children: A systematic literature review, Proceedings of ACM SIGCHI Interaction Design and Children Conference, ACM Press, New York (2015), 79-88.

Bruckman, Amy, Bandlow, Alisa, Dimond, Jill, and Forte, Andrea, Human-computer interaction for kids, in Jacko, Julie (Edi tor), The Human-Computer Interaction Handbook, 3rd Edition, CRC Press (2012), 841-862.

Center for Information Technology Accommodation, Section 508: The road to accessibility, General Services Administration, Washington, DC (2015). Available at http://www .section508.gov/ .

Chisnell, Dana E., Redish, Janice C., and Lee, Amy, New heuristics for understanding older adults as web users, Technical Conununications 53, 1 (February 2006), 39-59 .

Chourasia, A., Nordstrom, D., and Vanderheiden, G., State of the science on the cloud, accessibility, and the future, Universal Access in the Inforn1ation Society 13, 4 (2014), 483- 495.

Cunningham, Katie, Accessibility Handbook, O'Reilly Publishing (2012).

Czaja, S. J. (Editor), Human Factors Research Needs for an Aging Population, National Academy Press, Washington, DC (1990).

Czaja, S. J., and Lee, C. C., Older adults and information technology: Opportunities and challenges, in Jacko, Julie (Editor), The Hu1nan-Cornputer interaction Handbook, 3rd Edition, CRC Press (2012), 825-840.

Fails, J. A., Guha, M. L., and Druin, A., Methods and techniques for involving children in the design of new technology, Foundations and Trends in Hurnan-Cornputer Interaction 6, 2, Now Publishers Inc ., Hanover (2014), 85-166.

Foss, E., and Druin, A., Children's internet Search: Using Roles to Understand Youth Search Behavior, Morgan & Claypool Publishers (2014).

Hart, T. A., Chaparro, B. S., and Halcomb, C. G., Evaluating websites for older adults: adherence to "senior-friendly" guidelines and end-user performance, Behavior & Information Technology 27, 3 (May 2008), 191- 199.

Horton, Sarah, and Quesenbery, Whitney, A Web for Everyone: Designing Accessible User Experiences, Rosenfeld Media (2014).

Hourcade, J. P., Child-Cornputer Interaction, CreateSpace Independent Publishing (2015). Available at http:/ / homepage.di vms.uiowa.ed u /-hourcade/boo k/index.php.

Human Factors & Ergonomics Society, ANST/HFES 100-2007 Human Factors Engineering of Cornputer Workstations, Santa Monica, CA (2007).

Lazar, Jonathan, Goldstein, Daniel F., and Taylor, Anne, Ensuring Digital Accessibility through Process and Policy, Morgan Kaufmann (2015).

Lazar, J., and Ho chheiser, H., Lega l aspects of interface accessibility in the U.S ., Communications of the ACM 56, 12 (2013), 74-80.

Marcus, Aaron, and Gould, Emile W., Globalization, localization and cross-cultural user-in terface design, in Jacko, Julie (Editor), The Human-Computer interaction Hand­ book, 3rd Edition, CRC Press (2012), 341- 366.

Medhi, I., Patnaik, S., Brunskill, E., Gautama, N., Thies, W., and Toyama, K., Designing mobile interfaces for novice and low -literacy users, ACM Transactions on Con-1puter­ Hu1nan Interaction 18, l (2011), Article 2, 28 pages.

78 Chapter 2 Univ ersa l Usabil ity

Newell, Alan, Design and the Digital Divide: Insights fron1 40 Years in Con1puter Support for Older and Disabled People, Synthesis Lectures on Assistive, Rehabilitative, and Health­ Preserving Technologies (Ron Baecker, Editor), Morgan & Claypool Pub lishers (2011).

Pereira, Roberto, and Baranauskas, Maria C. C., A va lue-orien ted and culturall y in­ form ed approach to the des ign of int erac tive systems, International Journal of Hu1nan­ Cornputer Systems 80 (2015), 66-82.

Preedy, V. R. (Editor), Handbook of Anthropometry: Handbook of Hun1an Physical Form in Health and Disease, Springer Publi shers (2012).

Quese nbery, Whitn ey, and Szuc, Dan iel, Global UX: Design and Research in a Connected World, Morgan Kaufmann (2011).

Rad va nsky, Gabr iel A., and Ashcraft, Mark H., Cognition, 6th Edition, Pearson (2013).

Reinecke, Katharina, and Bern stein, Abraham, Knowing what a user likes: A design science approach to iI1terfaces that automatically adapt to cu ltur e, MIS Quarterly 37, 2 (2013), 427-453.

Salgado, L. C. C., Leitao, C. F., and de Souza, C.S., A JournetJ through Cultures: Metaphors for Guiding the Design of Cross-Cultural Interactive Syste1ns, Springer (2012).

Sun, Huatong, Cross-Cultural Technology Design, Oxford University Press (2012).

Ware, Colin , Information Visualization: Perception for Design, 3rd Edition , Morgan Kaufmann Publ., San Franci sco, CA (2012).

Went z, B., Jaeger, P., and Lazar, J., Retrofi tting accessibility: The inequality of after -the­ fact access for persons with disabilities in the United States, First Monday 16, 11 (2011).

Wiggms, J. S., The Five-Factor Model of Personalitt;: Theoretical Perspecti11es, Guilford Press (1996).

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CHAPTER

Guideli@esi •

99 We want principles, not only developed-the work of the closet- ,, but applied, which is the work of life.

Horace M ann Thoughts , 1867

•• There never comes a point where a theory can be said to be true . The most that anyone can claim for any theory is that it has shared

the successes of all its rivals and that it has passed at least one test '' which they have failed .

CHAPTER OUTLINE 3. 1 Introduction

3.2 Guidelines

3.3 Principles

3.4 Theories

A. J. Ayer Philosophy in the Twentieth Centur y, 1982

81

82 Chapter 3 Guidelines, Principles, and Theories

3.1 Introduction

User-in terface designers have accumulated a weal th of experience and research­ ers have produced a growing body of empirical evidence and theories, all of which can be organized into:

1. Guidelines. Low- level focused advice about good practices and cautions against dangers.

2. Principles. Middle -level strategies or rules to analyze and compare design alternatives.

3. Theories. High-level widely applicable fra1neworks to draw on during design and evaluation as well as to support comrnunicatio11 ai1d teaching. Theories can also be predictive, such as those for pointing times by indi­ viduals or posting rates for community discussions.

In many con temporary sys tems, designers have a grand opportuni ty to improve the user interface by applying es tablished guidelines to clean up clut­ tered displays, inconsistent layouts, and unnecessary text. These sources of debil ­ itating stress and frustration can lead to poorer performance, minor slips, and ser ious errors, all contributing to job dissatisfaction and consumer resistance .

Guidelines, principles, and theories, which offer preventive medicine and remedies for these problems, ha ve matured in recent yea rs (Grudin, 2012). Reli­ able methods for predicting pointing and input times (Chapter 10), better social persuasion principles (Chapter 11), and helpful cognitive or perceptual theories (Chapter 13) now shape research and guide design. International or national standards, which could be described as commonly accepted and precisely defined so as to be enforceable, are increasin gly influentia l (Carrol l, 2014).

This chapter begins with a sampling of guidelines for navigating, organizing displays, getting user attention, and facilitating data entry (Section 3.2). Then Section 3.3 covers some fundamental princip les of interface design, such as cop­ ing with user skill levels, task profiles, and interaction sty les. It presents the Eigh t Golden Rules of Interface Design, explores ways of preventing user errors, and closes with a section on ensuring human control while increasing automa­ tion. Section 3.4 reviews micro-HCI and macro-HCI theories of interface design.

3.2 Guidelines

From the earliest days of computing, interface designers have written down guidelines to record their insights and to try to guide the efforts of future design­ ers. The ear ly App le and Microsoft guidelines, which were influen tial for

Interface Elements v

Labels

Images

Groups

Pickers

Tablt-s

Buttons

Switchts

Sliders

Maps

Movies

Date and Timer labE-ls

Menus

Watch Technologies

Resources

FIGURE 3.1

3.2 Guidelines 83

Pickers Pickers display lists of items tlat are navigable using the Digital Crown. They are meant to be a precise and enga,ging way to mtinage selections. Pickers present their items in one of three styles:

List style displays text and image$ Stack style di.splays images in a card Sequence style displays one image

In a scrolling list Tius style displays stack sryle lnte,face. As che user from a sequence of Images. As the the selected item and the previous scrolls, images are animated into user rurns the Oigitail CrO'lvn, the

and next Items If those Items are position with the se&ected Image on picker displays the previous or next

available. top. This style is best for photo image in the sequence without

browser interfaces. animations. This style Is good fot

custom picker interfaces built using

your own Images.

Example of Apple gu idelines for design ing menus for the iWatch.

desktop-interface designers, have been followed by dozens of guidelines documents for the web ai1d mobile devices (Fig. 3.1) (see the list at the end of Chapter 1). A guidelines document helps by developing a shared language and then promoting consistency among 1nultiple designers in terminology usage, appearance, and action sequences. It records best practices derived from practical experience or empirical studies, with appropriate examples and counterexamples. The creation of a guidelines document engages the design community in lively discussions about input and output formats, action sequences, terminology, and hardware devices (Lynch and Horton , 2008; Hartson and Pyla, 2012; Johnson, 2014).

Critics complain that guidelines can be too specific, incomplete, hard to apply, and sometimes wrong. Propo11ents argt1e that building on experience from design leaders contributes to steady improvements. Both groups recognize the value of lively discussions in promoting awarerless.

The following four sections provid e exampl es of guidelines, and Section 4.3 discusses how they can be integrated into the design process. The examples address some key topics, but they mere ly sample the thousands of guidelines that have been written.

3.2. 1 Navigating the interface

Since navigation can be difficult for many users, providing c.lear ru.les is helpful. The sample guidelines pr esented here come from the U.S. government's efforts to

84 Chapter 3 Guidelines, Principles, and Theories

promote the design of informative webpages (National Cancer Institute, 2006), but these guidelines have widespread application. Most are stated positively ("reduce the user's workload"), but some are negative ("do not display unsolicited win­ dows or graphics"). The 388 guidelines, which offer cogent examples and impre s­ sive research support, cover the design process, general principles, and specific rules. This sample of the guidelines gives useful advice and a taste of their style:

Standardize task sequences. Allow users to perform tasks in the same sequence and manner across similar conditions.

Ensure that links are descriptive. When using links, the link text should accu­ rately describe the link's destination.

Use unique and descriptive headings. Use headings that are distinct from one another and concep tuall y related to the conten t they describe.

Use radio buttons for rnutually exclusive choices. Provide a radio button control when user s need to choose one response from a list of mutually exclusive options .

Develop pages that will print properly. If users are likely to print one or more pages, develop pages with widths that print properly.

Use thu111bnail i111ages to preview larger i111ages. When viewing full-size images is not critica l, first pro vide a thumbnail of the image .

Guidelines to promote accessibility for t1sers with disabilities were included il, the U.S. Rehabilitation Act. Its Section 508, with guidelines for web design, is pub ­ lished by the Access Board (http://www.access-board.gov/508.htm), an indepen­ dent U.S. government agency devoted to accessibility for people with disabilities. The World Wide Web Co11sortium (W3C) adapted these guideline s (http:/ /www. w3.org/TR/WCAG20/) and organized them into three priority levels, for which it has provided automated checking tools. A few of the accessibility guidelines are:

Text alternatives. Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, syn,bol s, or simp ler languag e.

Tinie-based 111edia. Provide alternatives for time-based media (e.g., movies or animations). Synchronize equivalent alternatives (such as captions or audi­ tory de scriptions of the visual track) >vith the presentation.

Distinguishable. Make it easier for users to see and hear conten t, including separating foreground from back groun d . Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

Predictable. Make Web pages appear and operate in predictable ways.

The goal of the se guidelines is to have webpage designers use features that per ­ mit users witl, disabilities to employ screen readers or other specia l technologies to give them access to webpage content.

3.2 Guidelines 85

3.2.2 Organizing the display Display design is a large topic with many special cases. An ear ly influential guidelines document (Smith and Mosier, 1986) offers five high-level goals for data display:

l. Consistency of data display. During the design process, the terminology, abbreviations, formats, colors, capitalization, and so on should all be standardized and controlled by use of a dictionary of these items.

2. Efficient information assimilation by the user. The format shou ld be familiar to the opera tor and should be related to the tasks required to be performed with the data. This objective is served by rules for neat columns of data, left justification for alphanumeric data , right justification of integers, lining up of decimal points, proper spacing, use of comprehensible labels, and appropriate measurement units and numbers of decimal digits.

3. Mini1nal n1enwry load on the user. Users shou ld not be required to remember information from one screen for use on another screen. Tasks sho uld be arranged such that completion occurs with few actions, minimizing the chance of forgetting to perform a step . Labels and common formats shou ld be provided for novice or intermittent users.

4. Compatibility of data display ivith data entry. The format of displayed information should be linked clearly to the format of the data entry. Where possib le and appropriate, the output fields shou ld also act as editable input fields.

5. Flexibility for user control of data display. Users should be able to get the information from the display in the form most convenient for the task on which they are working. For example, the order of columns and sorting of rows sho uld be easily changeab le by the users.

This compact set of high-level objectives is a useful starting point, but each proj­ ect needs to expa nd these into application-spec ific and hardware-dependent standards and practices.

3.2.3 Getting the user's attention Since substant ial information may be presented to users, exceptional conditions or time-dependent information must be presented so as to attract attention (Wickens et al., 2012). These guidelines detail several techniques for getting the user's attention:

• Intensity. Use two levels only, with limited use of high intensity to draw atterltion.

• Marking. Underline the item, enclose it in a box, point to it with an arrow, or use an indicator sttch as an asterisk, bullet , dash, plus sign, or X.

• Size. Use up to four sizes, with larger sizes attracting more attention.

• Choice of fonts. Use up to three fonts .

86 Chapter 3 Guidelines, Principles, and Theories

• Blinking. Use blinking displays (2-4 Hz) or blinking color changes w ith great care and in limited areas, as it is distracting and can trigger seizures.

• Color. Use up to four standard colors, with additional colors reserved for occasional use.

• Audio. Use soft tones for regular positive feedback and harsh sounds for rare emergency condi tions.

A few words of caution are necessary. There is a danger of creating clut ­ tered displays by overusing these techniques. Some web designers use blink­ ing advertisements or animated icons to attract attention, but users almos t uni versal ly disapprove. Animation is appreciated primarily when it provides meaningfu l information, such as for a progress indicator or to show move ­ ment of files.

Novices need simple, logically organ ized, and well- labeled displays that guide their actions. Expert users prefer limited labe ls on fields so data values are easier to extract; subtle highlighting of changed values or positional presentation is sufficient. Display formats must be tested with users for comprehensib ility.

Similarly highlighted items will be perceived as being related. Color-coding is especially powerful in linking related items , but this use makes it more difficult to cluster items across color codes (Section 12.5). User contro l over highlighting is much appreciated, for example, allowing cellphone users to select the color for contacts that are close family members or for meetings that are of high importance.

Audio tones, like the clicks in keyboards or cellphone ring tones, can provide informative feedback about progress. Alarms for emergency conditions do alert users rapidly, but a mechanism to suppress alarms must be provided. If several types of alarms are used, testing is necessary to ensure that users can distinguish between the alarm levels. Prerecorded or synthesized voice messages are a use­ ful alternative, but since they may interfere with communications between oper­ ators, they should be used cautiously (Section 9.3).

3.2.4 Facilitating data entry Data-entry tasks can occupy a substantial fraction of users' time and can be the source of frustrating and potentially dangerous errors . Smith and Mosier (1986) offer five high-leve l objectives as part of their guidelines for data entry (Courtesy of MITRE Corporate Archives: Bedford, MA):

1. Consistency of data-entry transactions. Similar sequences of actions speed learning.

2. Minin·,al input actions by user. Fewer input actions mean greater operator productivity and -u sually-f ewer chances for error. Making a choice by a sing le mouse selection or finger press, is preferred over typing in a lengthy string of characters. Selecting from a list of choices eliininates

3.2 Guidelines 87

the need for memorization, structures the decision-making task, and eliminates the possibility of typographic errors. A second aspect of this guideline is that redundant data entry should be avoided . It is annoying for users to enter the same information in two locations, such as entering the billing and shipping addresses when they are the same . Duplicate entry is perceived as a waste of effort and an oppor tunit y for error.

3. Mini,nal n1e1nory load on users. When doing data entry, users should not be required to remember lengthy lists of codes.

4. Con1patibility of data entry with data display. The format of data -entry information should be linked closely to the format of displayed infor1nation, such as dashes in telephone numbers.

5. Flexibility for user control of data entry. Experienced users prefer to enter in­ formation in a sequence that they can control, such as selecting the color first or size firs t, when clothes shopping .

Guidelines documents are a wonderful star ting point to give designers the ben­ efit of experience (Fig. 3.2), but they will always need processes to facilitate edu­ cation, enforcement, exemption, and enhancement (Section 4.3).

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" II II

88 Chapter 3 Guidelines, Principles, and Theories

3.3 Principles

While guidelines are low-level and narrowly focused, principles are more funda­ mental, widely applicable, and enduring. However, they also tend to need more clarification. For example, the principle of recognizing user diversity makes sense to every designer, but it must be thoughtfully interpreted. A preschooler playing a computer game is a long way from a legal librarian searching for precedents for anxious and hurried lawyers. Similarly, a grandmother sending a text message is a lorlg ,-vay from a highly trairled and experienced air-traffic controller . These examples highlight the differences in users' background knowledge, frequency of use, and goals as well as in the impact of user errors. Since no single design is ideal for all users and situations, designers who characterize their users and the context of use are more likely to produce st1ccessful products.

Chapter 2 introduced the individual differences that designers must address in pursuing universal usability. This section focuses on a few fundamental prin­ ciples, beginning with accommodating user skill levels and profiling tasks and user needs. It discusses the five primary interaction styles (direct manipulation, me11u selection, form fill-in, natural languag e, and command language) and the Eight Golden Rules of Interface Design, followed by a section on error preven ­ tion. Finally, it covers controversial strategies for ensuring human control while increasing automation.

3.3.1 Determine users' skill levels

Learning about the users is a simple idea but a difficult and, unfortunately, often under valued goal. No one would argue against this principle, but many design­ ers simply assume that they understand the users and the users' tasks. Success­ ful designers are aware that people learn, think, and solve problems in different ways. Some users prefer to deal with tables rather tl1an graphs, with words instead of numbers, or with rigid structures rather than open-ended forms.

All design should begin with an understanding of the intended users, includ­ ing population profiles that reflect their age, gender, physical and cognitive abilities, education, cultural or ethnic backgrounds, training, motivation, goals, and personality. There are often several communities of users for an interface, especially for web applications and mobile devices, so the design effort is mul­ tiplied. Typical user personas-such as nurses, doctors, storekeepers, high schoo l stud e11ts, or children -c an be expected to have various combina tions of knowledge and usage patterns. User groups from different countries may each deserve special attention, and regional differences often exist within countries. Other variables that charac terize user personas includ e location (for example, urban versus rural), economic profile, disabilities, and attitud es toward using

3.3 Principles 89

technology. Users with poor reading skills, limited education, and low moti, ,a­ tion require special attention.

In addition to these personas, an understanding of users' skills with inter­ faces and with the application domain is importa11t. Users might be tested for their familiarity with interface features, such as traversing hierarchical menus or drawing tools. Other tests might cover domain-specific abilities, such as knowledge of airport city codes, stockbrokerage terminology, or map icons.

The process of getting to know the users is never-ending because there is so much to know and because the users keep changing. However, every step toward understanding the users and recognizing them as individuals with out­ looks different from the designer's own is likely to be a step closer to a success­ ful desigi1.

For example, a generic separation into novice or first-time, knowledgeable intermittent, and expert frequent users might lead to these differing design goals:

1. Novice or first -time users. True novice users – for example, bank customers making their first cellphone check deposit-are assumed to know little of the task or interface concepts. By contrast, first-time users are often professiona ls who know the task concepts well but have shallow knowledge of tl1e interface concepts (for example, a business traveler using a new rental car's naviga­ tion system). Overcoming their uncertainties, via instructions or dialog boxes, is a serious challenge to interface designers. Restricting vocabulary to a small number of familiar, consistently used concept terms is essential. The number of actions should also be small so that novice and first-time users can carry out simple tasks successfully, which reduces anxiety, builds confidence, and pro­ vides positive reinforcement. Informati, re feedback about the accomplishment of each task is helpful, and constructive, specific error messages should be pro­ vided when users make mistakes. Carefully designed video demonstrations and online tutorials may be effective.

2. Knowledgeable inter,nittent users. Many people are knowledgeable but inter­ mittent users of a variety of systems (for example, business travelers filing for travel reimbursements). They have stable task concepts and broad knowledge of interface concepts, but they may have difficulty retaining the structure of menus or the location of features. The burden on their memories will be light­ ened by orderly structure in the menus, consistent termit1ology, and interfaces that emphasize recogiution rather than recall. These features will also help nov­ ices and some experts, but the major beneficiaries are knowledgeable intermit­ tent users. Protection from danger is necessary to support relaxed exploration of features and usage of partially forgotten action sequences. These users will benefit from context-dependent help to fill in missing pieces of task or interface knowledge.

90 Chapter 3 Guidelines, Principles, and Theories

3. Expert frequent users. Expert "power" users are thoroughly fami liar with the task and interface concepts ai1d seek to get their work done quickly. They de­ mand rapid response times, brief and non-distracting feedback, and the short­ cuts to carry out actions with just a few clicks or gestures.

Designing for one class of users is relatively easy; designing for several is much more difficult. When multiple user classes must be accommodated, the basic strategy is to permit a multi-layer (sometimes called level-structured or spiral) approach to learnin g. No vices can be taught a minimal subset of objects and actions with which to get started. They are most likely to make correct choices when they have only a few options and are protected from making mistakes ­ that is, when tl1ey are given a training-wheels interface. After gaining confidence from hands-on experience, these users can choose to progress to ever -greater levels of task concepts and the accompanying interface concepts. The learning plan should be governed by the users' progress through the task concep ts, enabling users to take on new interface concep ts when they are needed to sup­ port more complex tasks. For LLsers with strong knowledge of the task and inter ­ face concepts, rapid progress is possible.

For example, novice users of a cellphone can quickly learn to make/receive calls first, then to use the menus to change ring tones, and later to reset the pri­ vacy protections. The multi-layer approach helps users with different skill levels and promotes universal usabi lity (Shneiderman, 2003).

Another option for accommodating different user classes is to permit users to personaH ze the menu contents . A third option is to permit users to control the density of informative feedback that the user interface provides. Novices want more informative feedback to confirm their actions, whereas frequent users want less distracting feedback. Similarly, frequent users like displays to be more densely packed than do novices. Finally, the pace of interaction may be varied from slow for novices to fast for frequent users.

3.3.2 Identify the tasks After carefully drawing the user profile, the designers identify the tasks to be carried out. Every designer would agree that the tasks must be identified first, but too ofte11, the task analysis is done informally or incompletely. Task analysis has a long history (Hackos and Redish, 1998; Wickens et al., 2012), but successful strategies usually involve long hours of observing and interviewing users. This helps designers to understand task frequencies and sequences and make the tough decisions about wha t tasks to support. Some implementers prefer to include all possible actions in the hope that some users will find them helpful, but this causes clutter. However, mobile app designers are successful because the y ruthlessly limited functionality (for example, calendar, contacts, and to-do list) to guarantee simplicity .

3.3 Principles 91

High- level task actions can be decomposed into multiple middle-level task actions, which can be further refined into atomic actions that users execute with a single menu selection or other action. Choosing the most appropriate set of atomic actions is a difficult task . If tl1e atomic actions are too small, the users will become frustrated by the large number of actions necessary to accomplish a higher-level task. If the atomic actions are too large and elaborate, the users will need special options to get what they want from the user interface.

The relative task frequencies are important in shaping a menu tree. Frequent tasks should be near the top and therefore quick to carry out, while rare tasks are deeper down. Relative frequency of use is one of the bases for making archi ­ tectural design decisions. For example, in a text editor:

• Frequent actions might be performed by pressing special keys, such as the four arrow keys, Insert, and Delete.

• Less frequent actions might be performed by pressing a single letter plus the Ctrl key or by a selection from a pull-down menu – examples include under­ score, bold, and save.

• Infrequent actions or complex actions might require going through a sequence of menu selections or form fill-ins-for example, to change the margins or to revise default printers.

Similarly, cellphone users can assign their close friends and family members to speed-dial numbers so that frequent calls can be made easily by pressing a single key

Creating a matrix of users and tasks cai1 help designers sort out these issues (Fig. 3.3). In each box, the designer can put a check mark to indicate that this user carries out this task. A more precise analysis would include frequencies instead of just simp le check marks. Such user-needs assessment clarifies what tasks are essential for the design and which ones could be left out to preserve system simplicity and ease of learning.

3.3.3 Choose an interaction style When the task analysis is complete and the task objects and actions have been identified, the designer can choose from these five primary interaction styles: direct maiupulation, menu selectio11, form fill-in, command lai1guage, and natu­ ral language (Box 3.1 and Box 3.2). Chapters 7 through 9 explore these styles in detail; this summary gives a brief comparative overvie,v.

Direct manipulation When designers can create a visual representation of the ,vorld of action, the users' tasks can be greatly simplified because direct ma­ nipulation of familiar objects is possible. Examples of such visual and tangible user interfaces include the desktop metaphor, drawing tools, photo editing, and games. By pointing at visual representations of objects and actions, users can

92 Chapter 3 Gu idelines, Principles, and Theories

TASK Query by Update Query across Add Evaluate

JobTrtle Patient Data Patients Relations System

Nurse ** **

Physician ** *

Supervisor * * **

Appointme nt **** personnel

Medical -record ** ** * * maintainer

Clinica l *** * researcher

Database * ** ** * programmer

FIGURE 3.3 Frequency of Task by Job Title Hypo t hetica l frequency -of-use of data for a medica l clinic informa ti on system. Answe ring queries from appointment personnel about individual patients is the highest -frequency task{****), and lower-frequency use is shown with***,**, or*.

carry out tasks rapid ly and can observe the results immediately (for example, dragging and dropping an icon into a trash can). Context -aware, embedded, nat­ ural, and wearable user interfaces often extend the capacity of direc t manipula­ tion designs by allowi11g users to gesture, point, move, or even dance to achieve their goals. Direct manipulation is appealing to novices, is easy to remember for intermittent users, and, with careful design, can be rapid for frequent users. Chapter 7 describes direct manipulation and its application.

Navigation and menu selection In navigation and menu-selection systems, users review choices, select the one most appropria te to their task, and observe the effect. If the termino logy and the meaning of the items are understandable and distinct, users can accomplish their tasks with little learning or memorization and just a few actions. The greatest benefit may be that there is a clear structure to decision making, since all possib le choices are presented at one time. Tlus inter­ action style is appropriate for novice and intermittei1t users and can be appealing to frequent users if the display and selection mechanisms are rapid. For designers, menu-selection systems require careful task analysis to ensure that all functions are supported conveniently and that terminology is chosen carefully and used consis­ tently. User-interface-building tools tha t support menu selection provide an enor­ mous benefit by ensuring consistent screen design, validating completeness, and supporting maintenance. Navigation and menu selection is discussed in Chapter 8.

3.3 Principles 93

BOX 3.1 Advantages and disadvantages of t he five primary interaction styles.

Advantages

Direct manipulation

• Visually presents task concepts

• Allows easy learning

• Allows easy retention

• Allows errors to be avoided

• Encourages exploration

• Affords high subjective satisfaction

Navigation and menu selection

• Shortens learning

• Reduces keystrokes

• Structures decision making

• Permits use of dialog­ management too ls

• A llows easy support of error handling

Form fill -in

• Simplifies data entry

• Enables convenient assistance

• Permits use of form- management too ls

Command language

• Powerful

• A llows easy scripting and history keeping

Natural language

• Relieves burden of learning syntax

Disadvantages

• May be hard to program

• Accessibility requires special attention

• Presents danger of many menus

• May slow frequent users

• Consumes screen space

• Requires rapid display rate

• Consumes screen space

• Requires learning and retention

• Error-prone

• Requires clarification dia log

• May not show context

• May require more keystrokes

• Unpredictable

94 Chapter 3 Guidelines, Principles, and Theories

BOX 3.2 Spectrum of directness.

An example of progression toward more direct manipu lation: less recall/more recognition, fewer keystrokes/fewer clicks, less capability to make errors, and more visible context.

>MONTH/08: DAY/21

a. Command line

JAN FEB MAR APR MAY JUN JUL

Month AUG SEP OCT NOV DEC

MM/DD I 08/21

b. Form fill-in to reduce typing

Day I 21 l~I

d. Pull-down menus offer meaningful names and eliminate invalid values

MM~ DDl}I]

c. Improved form fill-in to clarify and reduce errors

◄ August ► s M T w T F s

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

(ID 22 23 24 25 26 27

28 29 30 31

e. 2-D menus to provide context, show valid dates, and enable rapid single selection

Form fill-in When data en try is required, menu selection alone usually be­ comes cumbersome, and form fill-in (also called fill in the blanks) is appropriate. Users see a display of related fields, move a cursor among the fields, and enter data where desired. With the form fill-in interaction style, users must under­ stand the field labels, know the permissible value s and the data-entry method, and be capable of responding to error messages. Since knowledge of the key­ board, labels, and permissible fields is required, some training may be neces­ sary. This interaction sty le is most appropriate for knowledgeable intermittent users or frequent users. Chapter 8 provides a thorough treatment of form fill-in.

Command language For frequent users, command languages (discussed in Section 9.4) provide a strong feeling of being in control. Users learn the syr,­ tax and can often express complex possibilities rapidly without having to read distracting prompts. However, error rates are typically high, training is neces­ sary, and retention may be poor. Error messages and online assistance are hard to provide because of the diversity of possibilities. Command languages and query or programming languages are the domain of expert frequent users, who often derive great satisfaction from mastering a complex language. Powerful advantages include easy scripting and history keeping.

3.3 Principles 95

Natural language Increasingly, user interfaces respond properly to arbitrary spoken (for example, Siri on the Apple iPhone) or typed natural-language state­ ments (for example, web search phrases). Speech recognition can be helpful with familiar phrases such as "Tell Catl1erine that I'll be there i11 ten minutes," but with novel situations users may be frustrated with the results (discussed in Chapter 9).

Blending several interaction styles may be appropriate when the required tasks and users are diverse. For example, a form fill-in interface for shopping checkout can include menus for items such as accepted credi t cards, and a direct-manipulation environment can allow a right-click that produces a pop-up menu with color choices. Also, keyboard commands can provide shortcuts for experts who seek more rapid performance than mouse selection.

Increasingly, these five interaction styles are complemented by using context, sensors, gestures, spoken commands, and going beyond the screen to include enriched environments that enable users to activate doors, change sound volume, or turn on faucets. These enriched environmen ts, such as those found in au tomo­ biles, game arcades, projected displays, wearable interfaces, musical instrumen ts, and sound spaces, go beyond the desktop and mobile devices to produce playful and useful effects. The expansion of user interfaces into clothing, furniture, build­ ings, implanted medical devices, mobi le platforms such as drones, and the Inter­ net of Things enriches traditional strategies and expands the design possibilities.

Chapters 7-9 expand on the constructive guidance for using the different interaction styles outlined here , and Chapter 10 describes how input and output devices influence these interaction styles. Chapter 11 deals with interaction when using collaborative interfaces and participating in soc ial media.

3.3.4 The Eight Golden Rules of Interface Design This section focuses attention on eight principles, called "golden rules," that are applicable in most interactive systems and enriched environments. These prin­ ciples, derived from experience and refined over three decades, require valida­ tion and tuning for specific design domains. No list such as this can be complete, but it has been well received as a useful guide to students and designers. The Eight Golden Rules are:

1. Strive for consistency. Consistent sequences of actions should be required in simi lar situations; identical terminology should be used in prompts, menus, and help screens; and consistent color, layout, capitalization, fonts, and so on, should be emp loyed throughout. Exceptions, such as required confirmation of the delete command or no echoing of passwords, should be comprehensible and limited in number.

2. Seek universal usability. Recognize the needs of diverse users and design for plasticity, facilitating transformation of content. Novice to expert differences,

96 Chapter 3 Guidelines, Principles, and Theories

age ranges, disabilities, international ,,ariations, and technological diversity each enrich the spectrum of requirements that guides design. Adding features for novices, such as explanations, and features for experts, such as shortcuts and faster pacing, enriches the interface design and improves perceived quality.

3. Offer informative feedback. For every user action, there sho uld be an interface feedback. For frequent and minor actions, the response can be modest, whereas for infrequent and major actions, the response should be more substantial. Visual presentation of the objects of interest provides a convenient environment for showing changes explicitly (see the discussion of direct manipulation in Chapter 7) .

4. Design dialogs to yield closure. Sequences of actions should be organized into groups with a beginning, middle, and end. Informative feedback at the completion of a group of actions gives users the satisfactio n of accomplishment, a sense of relief, a signal to drop conting ency plans from their minds, and an indicator to prepare for the next group of actions. For examp le, e-commerce websites move users from selecting products to the checkout, ending with a clear confirmation page that completes the transaction.

5. Prevent errors. As much as possible, design the interface so that users canno t make serious errors; for example, gray out menu items that are not appropriate and do not allow alphabetic characters in numeric entry fields (Section 3.3.5). If users make an error, the interface should offer simple, constr uctive, and specific instructions for recovery. For example, users should not have to retype an entire name-address form if they enter an invalid zip code but rather should be guided to repair only the faulty part. Erroneous actions should leave the interface state unchanged, or the interface should give instructions about restori ng the sta te.

6. Permit easy reversal of actions. As much as possible, actions should be reversible. This feature relieves anxiety, since users know that errors can be undone, and erlcourages exploration of unfamiliar options. The units of reversibility may be a single action, a data-entry task, or a complete group of actions, such as entry of a name-address block.

7. Keep users in control. Experienced users strongly desire the sense that they are in charge of the interface and that the interface responds to their actions. They don't wan t surprises or changes in familiar behavior, and they are annoyed by tedious data-entry sequences, difficulty in obtaining necessary information, and inability to produce their desired result.

8. Reduce short-te·mt memory load. Humans' limited capacity for information processing in short-term memory (the rule of thumb is that people can remember "seven p lus or minus two chunks" of information) requires that designers avoid interfaces in which users must remember information from

3.3 Principles 97

one display and then use that information on another display. It means that cellphones should not require reentry of phone numbers, website loca­ tions should remain visible, and lengthy forms should be compacted to fit a single display.

These underlying principles must be interpreted, refined, and extended for each environment. They have their limitations, but they provide a good start ­ ing point for mobile, desktop, and web designers. The principles presented in the ensuing sections focus on increasing users' productivity by providing sim ­ plified data -entry procedures, comprehensible displays, and rapid informa­ tive feedback to increase feelings of compe tence, mastery, and control over the system.

3.3.5 Prevent errors

•• There is no medicine against death, and agains t error no ru le has been found. ,,

Sigmund Freud (inscription he wrote on his portrait)

The importance of error prevention (the fifth golden rule) is so strong that it deserves its own section. Users of cellphones, e-mail, digital cameras, e-commerce websites, and other interactive systems make mistakes far more frequently than might be expected.

One way to reduce the loss in productivity due to errors is to improve the error messages provided by the interface. Better error messages can raise suc­ cess rates in repairing the errors, lower future error rates, and increase subjec­ tive satisfaction. Superior error messages are more specific, positive in tone, and constructive (telling users vvhat to do rather than merely reporting the problem). Rather than using vague (? or WHAT?) or hostile ( ILLEGAL OPERATION or SYNTAX ERROR) messages, designers are encouraged to use informative messages, such as PRI NTER IS OFF, PLEASE TURN IT ON or MONTHS RANGE FROM 1 TO 12.

Improved error messages, however, are only helpful medicine. A more effec­ tive approach is to pre, 1ent the errors from occurring. This goal is more attain­ able than it may seem in many interfaces.

The first step is to understand the nature of errors. One perspective is that people make mistakes or slips (Norman, 1983) that designers can help them to avoid by organizing scree11s and me11us functionall y, designing commands and menu choices to be distinctive, and making it difficult for users to take irrevers­ ible actions. Norman also offers other guidelines, such as providing feedback about the state of the interface (e.g., changing the cursor to show whether a map interface is in zoom-in or select mode) and designing for consistency of actions (e.g., ensuring that yes/no buttons are always displayed in the same order).

98 Chapter 3 Guidelines, Principles, and Theories

Norman's analysis provides practical examples and a useful theor y. Additional design techniques to reduce errors include the following:

Correct actions. Industrial designers recognize that successfu l products must be safe and must prevent users from dangerously incorrect usage of the products. Airplane engines cannot be put into reverse until the landing gear has touched down, and cars canno t be put into reverse while traveling for,,.,ard at faster than five miles per hour. Similar principles can be applied to interactive sys tems- for example, inappropriate menu items can be grayed out so they can't be inad ­ vertently selected, and web users can be allowed to simply click on the date on a calendar instead of having to type in a month and day for a desired air)jne flight departure. Likewise, instead of having to enter a 10-digit phone number, cellphone users can scroll through a list of frequent ly or recently dialed num ­ bers and select one with a single button press. A variant idea is to provide users with auto-completion for typing words, selecting from menus, or entering web addresses.

Complete sequences. Sometimes an action reqt1ires several steps to reach comp le­ tion. Since users may forget to complete every step of an action, designers may attempt to offer a sequence of steps as a single action. In automobiles, drivers do not have to set two switches to signa l a left turn; a single switch causes both (front and rear) tum-signal ligh ts on the left side of the car to flash. Likewise, when a pilot throw s a swi tch to lower the landing gear, hundreds of mechanical steps and checks are invoked automatically.

As another example, users of a text ed itor can indicate that all section titles are to be centered, set in uppercase letters, and underHned without having to make a series of selections each time they enter a section title. Then if users want to change the title style-for example, to eliminate underlining – a single change will guar­ antee that all section titles are revised consistently. As a final example, an air-traf­ fic controller may formulate plans to change the altitude of a plane from 14,000 feet to 18,000 feet in two increments; after raising the p lane to 16,000 feet, however, the controller may get distracted and fail to complete the action. The controller should be able to record the plan and then have the computer prompt for completion. The notion of complete sequences of actions may be difficult to implement because users may need to issue atomic actions as well as complete sequences . In this case, users should be allowed to define sequences of their own. Designers can gather information about potential complete sequences by studying sequences of actions that people actually take and tlle patterns of errors that peop le actually make.

Thinking about universal usability also contributes to reducing errors-for example, a design with too many small buttons may cause unacceptably high error rates among older users or otllers with limited motor control, but enlarg­ ing the buttons will benefit all users. Section 4.6 addresses the idea of logging user errors so designers can continuously improve designs.

3.3 Principles 99

3.3.6 Ensuring human control while increasing automation

The guidelines and principles described in the previous sections are often devoted to simplifying the users' tasks . Users can then avoid routine, ted iou s, and error-prone actions and can concentrate on making critical decisions, select­ ing alternatives if the original approach fails, and acting in unanticipated situa­ tions. Users can also make subjective value-based judgm ents, request help from other human s, and develop new so lution s (Sanders and McCormick, 1993). (Box 3.3 provides a detailed comparison of human and machine capabilities.)

Computer system designers have generally been increasing the degree of auto­ mation over time as procedures become more standardized and the pressure for productivity grows. With routine tasks, automation is desirable, since it red uces the potential for errors and the users' workload (Cummings, 2014). However, even with increased automation, informed designers can still offer the predictable and controllable interfaces that users usually prefer. The human supervisory role needs to be maintained because the real world is an open system (that is, a nonde­ numerable number of unpredictable events and system failures are possible). By contrast, computers constitute a closed system ( only a denumerable number of nor-

mal and failure situations can be accommodated in hardware and software).

BOX 3.3 Relative capabilities of humans and machines.

Hum ans Generally Bett er

• Sense-making from hearing, sight, touch, etc.

• Detect familiar signals in noisy background

• Draw on experience and adapt to situations

• Select alternatives if original approach fails

• Act in unanticipated situations

• Apply principles to solve varied problems

• Make subjective value-based judgments

• Develop new solutions

• Use information from external environment

• Request help from other humans

Machine s Generally Bett er

• Sense stimu li outside human's range

• Rapid consistent response for expected events

• Retrieve detailed information accurately

• Process data with anticipated patterns

• Perform repetitive actions reliably

• Perform several act ivities simultaneously

• Maintain performance over time

100 Chapter 3 Guidelines, Principles, and Theories

For example, in air-traffic control, common actions include changes to a plane's altitude, heading, or speed. These actions are well understood and potentially can be automated by scheduling and route-allocation algorithms, but the human controllers must be present to deal with the highly variable and unpredictable emergency situations. An automated system might deal success­ fully with high volumes of traffic, but what would happen if the airport man­ ager closed a runway because of turbulent weather? The controllers would have to reroute planes quickly. Now suppose that one pilot requests clearance for an emergency landing because of a failed engine, while another pilot reports a passenger with chest pains who needs prompt medical attention. Value-based judgment, possibly with participation from other controllers, is necessary to decide which plane should land first and how much costly and risky diversion of normal traffic is appropriate. Air-traffic cor1trollers cannot just jump into ar1 emergency; they must be intensely involved in the situation as it develops if they are to make informed and rapid decisions. In short, many real-world situ ­ ations are so complex tha t it is imp ossible to an ticipat e and program for every contingency; human judgment and values are necessary in the decision­ making process.

Another example of the complexity of life-critical situations in air -traffic con­ trol was illustrated by an incident on a plane that had a fire on board. The con­ troller cleared other traffic from the flight path and began to guide the plane in for a landing, but the smoke was so thick that the pi lot had troub le reading his instruments. Then the onboard transponder burned out, so the air-traffic con­ troller could no longer read the plane's altitude from the situation display. In sp ite of these multiple failures, the controller and the pilot managed to bring down the plane quickly enough to save the lives of many-but not all-of the passengers. A computer could not have been programmed to deal with this par ­ ticul ar unexpected series of events.

A tragic outcome of excess of aut omation occurred during a flight to Ca li, Colombia. The pilots re lied on the automatic pilot and failed to realize that the plane was making a wide turn to return to a location that it had already passed. When the ground-collision alarm sounded, the pilots were too disoriented to pull up in time; they crashed 200 feet below a mountain peak, killing all but four peop le on board.

The goal of design in many applications is to give users sufficient information about current status and activities to ensure that, when intervention is neces­ sary, they have the knowledge and the capacity to perform correctly, even under partial failures (Endsley and Jones, 2004). The U.S. Federal Aviation Agency stresses that designs should place the users in contro l and automate only to "improve system performance, without reducing human involvement" (U.S. FAA, 2012). These standards also encourage managers to "train users when to question automation ."

3.3 Principles 101

The entire user interface must be designed and tested not only for normal situ­ atio11s but also for as wide a range of anomalous situations as can be anticipated. An extensive set of test conditions might be included as part of the requirements document. Users need to have enough information that they can take responsi­ bility for their actions. Beyond decision making and handling of failures, the users' role is to improve the interface design.

Advocates of increased autonomy, such as in driverless cars or unmanned aircraft, believe that rapid autonomous responses improve performance and produce fewer errors. However, autonomy has risks for unanticipated situa­ tions, such as changing weather or unusual trading activity. In 2015, Toyota shifted its driverless car research from autonomous designs to ones that leave drivers in control. The dangers of unanticipated situations for Unmanned Aerial Vehicles (UAVs) resulted in shifting to Remotely Piloted Vehicles (RPVs) with human control to improve reliability. While autonomy has its benefits, designs that allow human supervisory control, activity logging, and the capacity to review logs after failures appear to improve performance.

In costly business situations, such as high-speed stock market trading, clarify­ ing responsibility for failures could lead to improved designs. Ensuring account­ ability and liability in advance can encourage designers to think more carefully abou t potential failures. Advocates of "algorithmic accountab ility" want devel­ opers who implement systems such as Google's search rankings or employee hiring systems to enable open access so as to limit bias and expose errors.

Questions about integrating automation with human control also emerge in consumer product user interfaces. Many designers are eager to create an auton­ omo us agent that knows people's likes and dislikes, makes proper inferences, responds to novel situations, and performs competent ly with litt le guidance. They believe that human-human interaction is a good model for human­ computer interaction, and they seek to create computer-based partners, assis­ tants, or agents.

By contrast, many designers believe that tool-like interfaces are often more attractive than autonomous, adaptive, or anth ropomorphic agents that carry out the users' intentions and anticipate needs. The agent scenarios may show a bow­ tied butler-like human, like the helpful young man in App le Computer's famous 1987 video on the Knowledge Navigator. Microsoft's ill-fated 1995 BOB program used cartoon characters, while its much-criticized Clippit, nicknamed Clippy, character was also withdrawn. Human -like bank machines or postal-service sta­ tions have largely disappeared, but avatars representing users, not computers, in game-playing and 3-D socia l environments have remained popular; users appear to enjoy the theatrical experience of creating a new identity, sometimes with colorful hair and clothes (Section 7.6).

The success of Apple's Siri's speech recognition and personality-rich voice response system shows that with careful development, useful tools ca11 be

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deve loped, but there is little evidence of the benefit of a talking face (Moreno and Mayer, 2007). Robot designers have perennially used human and animal forms as an inspiration, encouraging some researchers to pursue human-like robots for care of older adults or as team members in work situations. These designs attract journalists and have entertainmen t value but have yet to gain widespread acceptance.

A variant of the agent scenario, which does not include an ai1thropomorphic realization, is that the compu ter program has a built-in user model to guide at, adaptive interface. The program keeps track of user performance and adapts the interface to suit the users' needs. For example, when users begin to make menu selections rapidly, indicating proficiency, advanced menu items may appear. Au tomatic adaptations have been proposed for interface features such as the content of menus, order of me11u items, and type of feedback (graphic or tabu ­ lar) . Advocates point to video games that increase the speed or number of dan ­ gers as users progress through game levels. Ho.vever, games are notably different from most work situation s, where users bring their goals and motiva­ tion s to accomplish tasks.

There are opportunities for adaptive user models to tailor designs (such as for e-mail spam filters or search results ranking), but unexpected interface behavior can have nega tive effects that discourage use. If adaptive sys tems make surpri s­ ing cha11ges, such as altering the search results ranking, users may be puzzled about what has happened. Users may become anxious because they cannot pre ­ dict the next change, interpret what has happened, or return to the previous state . Users may also be annoyed if a one-time purchase of a children's book as a gift leads to repeated promotions of more children's books.

An application of user mode ling is reco1nmender systems in web applications. In this case, there is no agent or adaptation in the interface, but the program aggregates information from multiple sources in some (often proprietary) way. Su.ch approaches have great practical val ue such as suggesting movies, books, or music; users are often intrigued to see what suggestions emerge from their purchasing patterns. Amazon.com and other e-commerce companies success ­ fully suggest that "customers who bought X also bought Y."

The philosophical alternative to agen ts and user mod eling is to design com­ prehensible sys tems that provide consistent interfaces, user control, and predict­ able behavior. Designers who emphasize a direct -manipulation style believe that users have a strong desire to be in control and to gain mastery over the system, which allows them to accept responsibility for their actions and derive feelings of accomplishment (Shneiderman, 2007). Historical evidence suggests that users seek comprehensible and predictable sys tems and shy away from those that are complex or unpredictable; for example, pilots may disengage automatic piloting devices if they perceive that these systems are not performing as they expect.

Agent advocates promote au tonomy, but this means they must take on the issue of responsibility for failures. Who is responsible when an agent viola tes

Settings

@ PERSONALIZATION

Background

Colors

Lock screen

Themes

Start

FIGURE 3.4

3.3 Principles 103

I Find a setti ng

Start

Show most used apps

tll) On

Show recently added apps

tll) On

Use Start full screen

<• ) Off

□

Show recently opened items in Jump Lists on Start or the taskbar

tll) On

Choose which folders appear on Start

X

Windows 10 system preferences include control pane ls for personalization. Here we see the Start options, which allow users to control what items will display in the Start menu and taskbar .

copyright, invades privacy, or destroys data? Agent designs might be better received if they supported performance monitoring while allowing users to examine and revise the current user model.

An alternative to agents with user models may be to expand the control-panel model. Computer control panels (sometimes called settings, options, or prefer­ ences), like automobile cruise-control mechanisms and television remote con­ trol s, are designed to convey the se11se of control that users seem to expect. Users employ contr ol panels to set physical parameters, such as the cursor blinking speed or speaker volume, and to establish personal preferences such as time/ date formats, color schemes, or the content of start menus (Fig. 3.4). Some soft­ ware pa ckages allow users to se t param eters such as the speed of play in games. Use rs start at layer 1 and can then choose when to progre ss to higher levels; often they are content to remain experts at layer 1 of a complex interface rather than dealing with the uncert ainties of higher layers. More elaborate control pan­ els exist in style shee ts of word processors, specifica tion boxes of query facilities, and sliders of information-visualization tool s.

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3.4 Theories

One goal for the discipline of human-computer interaction is to go beyond the specifics of guidelines and build on the breadth of principles to develop tested, reliable, and broadly usefu l theories. Of course, for a topic as large as user­ interface design, many theorie s are needed (Carroll, 2003; Rogers, 2012; B0dker, 2015).

Some theories are descriptive; these are helpful in developing consistent termi­ nology and useful taxonomies, for objects and actions, thereby supporting col­ laboration and training. Other theories are explanatory, describing sequences of events and, where possible, cause and effect, making interventions possible. Still other theories are prescriptive, giving designers clear guidance for their choices. Finally, the most precise theories are predictive, enabling designers to compare proposed designs for execution time, error rates, conversion rates, or trust levels.

Another way to group theories is according to the types of skills involved, such as n1otor (pointing with a mouse), perceptual (finding an item on a display), or cognitive (planning the sequence of steps needed to pay a bill) (Norman, 2015). Motor skill performance predictions are well established and accurate for pre­ dicting keystroking or pointing times (see Fitts's Law, Section 10.3). Perceptual theories have been successful in predicting reading tunes for free text, lists, for­ matted displays, and other visual or auditory tasks. Cognitive theori es, involv­ ing sho rt-term , working, and long -term memory, are central to problem solvit1g and play a key role in understanding productivity as a function of system response time (Chapter 12). However, predicting performance on complex cog­ nitive tasks (combinations of sub tasks) is especially difficult because of the many stra tegies that might be employed and the mai1y opportunities for goit1g astray. The ratio of tunes needed to perform complex tasks between novices and experts or between first -tune and frequent users can be as high as 100 to 1. Actu­ ally, the contras t is even more dramatic because novices and first-time users often make errors and are unable to complete the tasks.

Web designers have emphasized information-architecture theories with navi ­ gation as the keys to user success. Web users can be considered as foraging for informati on, and therefore the effective ness of the infor1nation scent of links is the issue (Pirolli, 2007). A high-quality link, relative to a specific task, gives users a good scent (or indication) of what is at the destination. For example, if users are trying to find a demonstration of a sofu ,vare package, a link with the text "download demo" has a good scent. The challenge to designers is to under­ stand user tasks well enough to design a large website such that users will be able to find their way successfu lly from a home page to the right destination, even if it is three or four clicks away. Information-foraging theory attempts to

3.4 Theories 105

BOX 3.4 Multiple theory types that researchers and designers consider when evaluating user interfaces.

By Theory Type

• Descriptive Describes user interfaces and their uses with consistent termino logy and taxonomies

• Explanatory Describes sequences of events with causal relationships

• Prescriptive Offers guide l ines for designers to make decisions

• Predictive Enables comparison of design alternatives based on numeric predictions of speed or errors.

By Human Capacity

• Motor

• Perceptual

• Cognitive

Ski ll in pointing, clicking, dragging, or other movements

Visual, auditory, tacti le, and other human sensory inputs

Problem solving with short- and long-term memory

predict user success rates given a set of tasks and a website so as to guide refinements.

Taxononii es can be an important part of descriptive and explanatory theo­ ries. A taxonomy imp oses order by class ifying a complex se t of phenomena into understandable categories. For example, a taxonomy might be created for different kinds of input devices: direct versus indirect, linear versus rotary, 1-, 2-, 3- or higher-dimensional, and so on (Card et al., 1990). Other taxonomies might cover tasks (structured versus unstructured, novel versus regular) or user-interface styles (direct manipulation, menus, form fill-in). An important class of taxonomies has to do with the individual differences among users, such as personality styles (convergent versus divergent, field­ dependent versus independent), technical aptitudes (spatial visuali zation, reasoning), and user experience levels (novice, knowledgeable, expert). Taxonomies facilitate useful comparisons, organize topics for newcomers, guide designers, and often indicate opportunities for novel products-for example, a task by type taxonomy organi zes the information visuali zation s in Cl1apter 16.

Any theory that might help designers to predict performance for even a lim­ ited range of users, tasks, or designs is a contribution. At the moment, the field is filled with hundreds of theories competing for attention while being refined by their promoters, extended by critics, and applied by eager and l1opeful- but skeptical-designers (Carroll, 2003, 2014; Rogers, 2012). This development is healthy for the growing discipline of human-computer interaction, but it means

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that practitioners must keep up with the rapid developments not only in soft­ ware tools and design guidelines but also in theories. Critics raise two chal­ lenges:

1. Theories should be 1nore central to research and practice. A good theory should guide researchers in understanding relationships between concepts and generalizing results. It should also guide practitioners when making design tradeoffs for products. The power of theories to shape design is most apparent in focused theories such as Fitts's Law; it is more difficult to demonstrate for explanatory theories, whose main impact may be in educating the next generation of designers .

2. Theories should lead rather than lag behind practice. Critics remark that too often a theor y is used to explain what has been produced by commercial product designers. A robust theory should predict or at least guide practitioners in designing new products. Effective theories sl1ould suggest novel products and services while helping to refine existing ones.

Another direction for theoreticians is to predict the subjective satisfaction or emotional reactions of users. Researchers in media and advertising have recog­ nized tl1e difficulty of predicting emotional reactions, so they complement theo­ retical predictions with their intuitive judgments and extensive market testing (Nahl and Bilal, 2007).

Broader theories of small-group behavior, organizational dynamics, and soci­ ology are proving to be useful in understai1ding social media and collaborative interfaces (Chapter 11). Similarly, the methods of antluopology or social psy­ chology may be helpful in understanding technology adoption and overcoming barriers to new technology that cause resistance to change.

There may be "nothing so practical as a good theory," but coming up wi th an effective theory is often difficult. By definition, a tl1eory, taxonomy, or model is an abstraction of reality and therefore must be incomplete. However, a good theory should be understandable, produce similar conclusions for all who use it, and help to solve design problems. This section reviews a range of descriptive and explanatory theories.

3.4.1 Design-by-levels theories One approach to developing descriptive theories is to separa te concepts accord­ ing to levels . Such theories have been helpful in software engineering and net ­ work design. An appealing and easily comprehensible design-by-levels theory for interfaces is the four-level concep tual, seman tic, syn tactic, and lexical theory (Foley et al., 1995):

1. The conceptual level is the user's "menta l model" of the interactive system. Two menta l models for image crea tion are paint programs that manipulate pixels and drawing programs that operate on objects. Users of paint programs think in terms of sequences of actions on pixels and groups of

3.4 Theories 107

pixels, while users of drawing programs think in terms of sequences of actions on objects and groups of objects. Decisions about mental models affect each of the lower levels.

2. The seniantic level describes the meanings conveyed by the user's input and by the comp ut er's output display. For example, deleting an object in a drawing program could be accomplished by undoing a recent action or by invoking a delete -object action. Either action should eliminate only a single object and leave the rest untouched.

3. The syntactic level defines how the user actions that convey semantics are assembled into comp lete sen tences to perform cer tain tasks . For example, the delete-files action could be invoked by dragging an object to a trash can followed by a click in a confirmation dialog box.

4. The lexical level deals with device dependencies and with the precise mecha­ nisms by which users specify the syntax (for example, a function key or a mouse double-click within 200 milliseconds).

This four-level theory is convenient for designers because its top -down nature is easy to explain, matches the software architecture, and allows for use­ ful modularity during design. Over the years, the success of graphica l direct­ manipulation interfaces has shifted attention up to the conceptual level, which is closest to the task domain (Parusl1, 2015). For example, designers of personal financial interfaces often use direct-manipulation it1terfaces. These interfaces build on the users' mental model of writing checks by showing the image of a check for users to fill in. The same image of a check serves as the query template so users can specify dates, payees, or amounts.

Increasingly, actions are shown by novel visual representations (for example, a trash can for deletion or a play button to start playing a video). Users have to learn the semantics (e.g., that they can recover a file by opening up the trash can or stop a video by clicking on the pause button), but if the designers choose familiar objects to associa te with the actions, users can quickly acquire the cor­ rect mental model for operating the user interface. Of course, users also have to learn the syntax of dragging objects or clicking to initiate the actions, but these mechanisms are common ly used and have become we!J known.

The idea of design-by-levels is successf ul even in more comp lex systems with many objects and actions. For example, the human body can be discussed in terms of neural, muscular, skeletal, reproductive, digestive, circulatory, and other su.bsystems, which in tum mjght be described in terms of organs, tissues, and cells. Most real-world objects have similar decompositions: buildings into floors, floors into rooms , rooms into doors/walls/windows, and so on. Similarly, movies can be decomposed into scenes, scenes into shots, and shots into dia­ logue, images, and sounds. Since most objects can be decomposed in many ways, the designer's job is to create compre hensible and memorable leve ls of objects.

In parallel with the decomposition of objects, designers need to decompose complex actions into several smaller actions. For example, a baseball game has

108 Chapter 3 Guidelines, Principles, and Theories

innings, pitches, runs, and outs, and a building-construction plan can be reduced to a series of steps such as surveying the property, laying the founda­ tion, building the frame, raising the roof, and completing the interior. Most actions can also be decomposed in many ways, so again the designer's job here is to create comprehensible and memorable levels of actions. The goal of sim­ plifying interface concepts while presenting visua l representations of the objects and actions involved is at the heart of the direct-manipulation approach to design (Chapter 7).

When a complete user-interface design has been made, the user ta sks can be described by a series of actions. These precise descriptions can serve as a basis for predicting the time required to perform tasks by simply counting up the number of milliseconds needed to complete all the steps. For examp le, resizing a pl1oto may require several mouse drags, selections of menu items, clicks on dialog box buttons, and typing of dimensions, but each of these actions takes a predictable amount of time. Several researchers have success­ fully predicted the tim e required for complex tasks by adding up the tim es required for each componen t action. This predictive approach, based on goals, operators, methods, and selection rules (GOMS), decomposes goa ls into many operators (actions) and then into methods. Users apply selection rules to choose among alterna te methods for achieving goals (Card et al., 1983; Baumeister et al., 2000).

The GOMS approach works best when the users are expert and frequent users who are working on their own, ful ly focused on the task, and make no mistakes. Advocates of GOMS have developed software tools to simplify and speed up the modeling process in the hope of increasing usage (John, 2011). Critics complain that broader theories are needed to predict novice user beha v­ ior, the transition to proficiency, the rate of errors, and retention over time.

Designers have discovered that using design-by-levels theories forces clear definitions of the high -Je,rel objects and actions, which are gathered from listen­ ing to the language used in the task domain. Music can be thought of as songs, organized by artists, albums, and gen res. Users can find a song and then play it or add it to a play list. The clarity of this conceptual structure earned it a patent and has stimulat ed multiple comme rcial successes.

3.4.2 Stages-of-action theories Another approach to forming explanatory theories is to portray the stages of action that u sers go through in using interactive products su ch as informati on appliances, web interfaces, or mobile devices (e.g., music players). Normai1 (2013) offers seven stages of action, arranged in a cyclic pattern, as an explana ­ tory theory of human-computer interaction:

1. Forming the goal

2. Forming the intention

3.4 Theories 109

3. Specifying the action

4. Executing the action

5. Perceiving the system state

6. Interpreting the system state

7. Evaluating the outcome

Some of Norman's stages correspond roughly to Foley et al.'s (1995) separa­ tion of concerns; that is, users form a conceptual intention, reformulate it into the semantics of several commands, construct the required syntax, and eventu­ ally produce the lexical token by the action of moving the mouse to select a point on the screen. Norman makes a contribution by placing his stages in the context of et;cles of action and evaluation, which take place over seconds and minutes. This dynamic process of action distinguishes Norman's approach from the other theories, which deal mainly with knowledge that must be in the user's mind. Furthermore, the seven stages of action lead naturally to identification of the gulf of execution (the mismatch between the user's intentions and. the all.owable actions) and the gulf of evaluation (the mismatch between the system's represen­ tation and the user's expectations).

This theory leads Norman to suggest four principles of good design:

1. The state and the action alternatives should be visible.

2. There should be a good conceptual model with a consistent system image.

3. The interface should include good mappings that reveal the relationships between stages.

4. Users should receive continuous feedback.

Norman places a hea, ,y emphasis on studying errors, describing how errors often occur in moving from goals to intentions to actions and to exect1tions.

The stages-of-action theory helps designers to describe user exploration of an interface (Polson and Lewis, 1990). As users try to accomplisl1 their goals, there are four critical points where user failures can occur: (1) users may form inade­ quate goals, (2) users might not find the correct interface object because of an incomprehensible label or icon, (3) users may not know how to specify or execute a desired action, and (4) users may receive inappropriate or misleading feedback.

Refinements of the stages-of-action theory have been developed for other domains. For example, information seeking has been characterized by these stages: (1) recognize, (2) accept the information problem, (3) formulate and (4) express the query, then (5) examine the results, (6) reformulate the problem, and (7) use the results (Marchionini and White, 2007). Of course, there are varia­ tions with users skipping stages or going back to earlier stages, but the model helps guide designers and users.

Commercial website designers know the benefit of a clear stages-of-action theory in guiding anxious users through a complex process. For example, the Amazon.com website converts the potentially confusing checkout process into a

110 Chapter 3 Guidelines, Principles, and Theories

comprehensible four -stage process: (1) Sign-in, (2) Shipping & Payment, (3) Gift-Wrap, and (4) Place Order. Users can simply move through these four stages or back up to previous stages to make changes. Amazon.com also recog­ nizes the 11eed for a frequent user shortcut, the I-click purchase, for products such as a Kindle book.

Designers can apply the stages-of-action theory by thinking deeply about the beginning, middle, and end stages to ensure that they cover a wide enough scope of usage. Many new products emerge as a result of adding novel features to what was considered a well-defined process; for examp le, expanding the music-playing process to include the earlier stages of music purchase or compo­ sition and the later stages of music sharing or reviewing/rating.

3.4.3 Consistency theories An important goal for designers is a consistent user interface. The argument for cons istency is that if terminology for objects and actions is orderly and describ­ able by a few rules, users will be ab le to learn and retain them easily. This exam­ ple illustrates consistency and two kinds of inconsistency (A illustrates lack of consistency, and B shows consistency except for a single violation):

Consistent Inconsistent A Inconsistent B

delete/ insert table delete I insert table de lete/ insert table

delete/ insert column remove/ add column remove/insert column

delete/ insert row destro y/ create row delete/insert row

delete/ insert border erase/ draw border delete/insert border

Each of the actions in the consistent version is the same, whereas the actions vary for inconsisten t versio n A. The inconsistent action verbs are all accep table, but their var iety suggests that they will take longer to learn , will cause more errors, wi ll slow down users , and will be harder for users to remember. Inconsistent version B is somehow more startling, because there is a single unpredictable inconsistency; it stands out so dramatically that this language is likely to be remembered for its peculiar inconsistency.

Consistency for objects and actions (nouns and verbs) is a good starting point, but there are many other forms of consistency that require careful thought by designers. Consistent use of color, layout, icons, fonts, font sizes, button sizes, and much more is v ital in giving users a clear understanding of tl1e interface. Inconsistency in elements such as the positioning of buttons or colors will slow users down by 5-10 %, while changes to terminology slow users by 20-25 %.

Consistency is an important goal, but there may be conflicting forms of consis­ tency, and sometimes inconsistency is a virtue (for example, to draw attention to a dangerous action). Competing forms of consistency require designers to make difficult choices or invent new strategies. For example, while automobi le

3.4 Theories 111

interface designers have agreed to always place the accelera tor pedal to the right of the brake pedal, there's no agreement about whether turn signal controls should be to the right or left of the steering wheel.

Consistency issues are critical in the design of mobile devices. In successful products, users get accustomed to consistent patterns, such as initiating actions with a left-side button while terminating actions with a right-side button. Simi­ larly, up and down scrolling actions should be done consistently using buttons tha t are vertically aligned. A frequent problem is the inconsistent placement of the Q and Z characters on phone buttons.

Designers can enforce consistency by developing detailed guidelines docu ­ ments for their designs (Section 4.3) that spell out all of the consistency require­ ments. Exper t reviewers of user it1terfaces can then verify the consistency of the design. This requires a careful eye and thoughtful attention to how each screen is laid out, each action sequence is carried out, and each sound is played.

3.4.4 Contextual theories

The design -by-levels, stages-of -action, and consistency theories address the spe­ cifics of how objects and actions appear on displays and what actions users take to carry out their tasks. These theories and design aspects might be called micro-HCI, since they cover measurable performance in terms of speed and errors. Micro -HCI is best studied with the scientific methods of experimental and cognitive psychology using 30- to 120-mmute controlled experiments and statistical tests for significant differences between groups workmg on well­ defined tasks

Micro-HC I has been and continues to be a great success story, but there is a growmg awareness that tightly controlled laboratory studies of isolated phe­ nomena are only one part of the story. The rise of nuzcro-HCI, which emphasi zes the user experience, the usage context, and social engagement, has opened up new possibilities for researchers and practitioners. While micro-HC I research is more about laboratory studies to collect clear performance measures for identi­ fiable tasks (e.g., how many seconds to fmd the last flight on July 4 from Washington, DC, to London), macro -HCI research is more about ethnographic observation of users doing work or play in their familiar context over days or even months. The outcomes of micro-HCI research are statistically significant differences that support or refute a hypothesis, while the outcomes of macro­ HCI research are insights about what leads to increased user satisfaction, how the context of use ma tters, and how new applications could improve education, health, safety, or the environment.

Macro-HCI thinking leads to different kmds of theories that might best be called contextual, since they co11sider the emotional, physical, and social con­ texts of use. Happy users will persevere in the face of frustrations, cope with mterruptions from neighbors, and ask for help when they need it. In short, tl1e

112 Chapter 3 Guidelines, Principles, and Theories

BOX 3.5 Theory types that organize evaluation of user interfaces and guide design .

Micro -HCI Theories Focus on measurable performance (such as speed and errors) on multiple standard tasks taking seconds or minutes in laboratory environments

• Design-by-levels Start with high-level design and move to smaller objects and actions

• Stages-of-action Consider user behavior as they form intentions and seek to realize their goals.

• Consistency Strive for consistency in objects and actions, shown by words, icons, co lors, shapes, gestures, menu choices

Macro -HCI Theories Focus on case studies of user experience over weeks and months in realistic usage contexts with rich social engagement

• Contextual Support users who are embedded in emotional, physica l, and social environments

• Dynamic Design for evo luti on of user behavior as users move through leve ls of mastery, performance, and leadership

physical and social env ironments are inextricably intertwined with use of information and communications technologies. Design cannot be separated from patterns of use.

Suchman's (1987) analysis in her book Plans and Situated Action is often cred ­ ited with launching this reconsideration of human-computer interaction. She argued that the cognitive model of orderly human plans that were executed when needed was insufficient to describe the richer and livelier wor ld of work or personal usage. She proposed that users' actions were situated in time and place, making user behavior highly responsive to other people and to environmental contingencies. If users got stuck in using an interface, they might ask for help, depending on who was around, or consu lt a manual, if one were avai lable. If they were pressed for time, they might risk some shortcuts, but if the work was life-critical, they wou ld be extra cautious. Rather than having fixed plans, users cons tantl y changed their plans in respo11se to tl1e circumstances. The argument of distributed cognition is that knowledge is not only in the users' minds but distributed in their environments-knowledge is stored on paper documents, accessible from electronic files, or available from colleagues.

Co11textual theories also address the shif t from use of a computer to interac­ tion wi th a device-rich environment filled with sensors, responsive appliances, display walls, and audio generators. Rather than picking up a device, users

3.4 Theories 113

activate automatic doors, hand dryers, or ligh t switches. Sometimes users are inside a device such as an automobile, forcing designers to consider the sur­ rounding space and the other people in the car as well as the sounds, vibrations, and forces of acceleration. Contextual theories often emphasize the social envi­ ronment in which users are engaged with other people who can provide assis­ tance or can be distractions.

Advocates of contextual theories believe that the turbulence of actual usage (as opposed to idealized task specifications) means that users have to be more than test subjects – they have to be participants in design processes. Proponents of contextual theories encourage more ethnographic observation, longitudinal case studies, and action research by participant observers (Boellstorff et al., 2012; Crabtree et al., 2012; Horst and Miller, 2013).

Breakdowns are often seen as sources of insight about design, and users are encouraged to become reflective practitioners who are continuously engaged in the process of design refinement. Understanding the transition from novice to expert and the differences in skill levels has become a focus of attention, further calling into question the utility of hour-101,g laboratory or half-day usability-test­ ing studies as a guide to the behavior of users after a month or more of experience.

Contextual theories are especially relevant to mobile devices and ubiquitous computing innovations. Such devices are portab le or installed in a phys ical space, and they are often designed specifically to provide place-specific information (for example, a city gu ide on a portable computer or a museum guide that gives information on a nearby painting). Location information by way of GPS systems enables new services but raises concerns about misuse of tracking information.

Designers can apply contextual theories by observing t1sers in their own environments as they carry out their work, engage socia lly, or participate in sports or play. A detailed record of how tasks are chosen and carried out, including collaborations with others, internal or external interruptions, and errors that occur, would lay the basis for interface design. Contextua l theories are about how people form inten tions, how aspirations crystalize, how empa­ thy is encouraged, and how trust shapes behavior; they are also about emotional states of excitement or frustration, the joy of attaining goals, and the disappointment of failure. These strong reactions are hard to capture in predic­ tive mathematical equations, but it is important to study and understand them. To that end, many researchers are shifting their me thods from controlled experiments to ethnographic observation, focus group discussions, and long­ term case studies. Surveys and interviews can provide quantitative data for much-needed theories of how design variab les affect users' levels of satisfac­ tion, fear, trust, and cooperativeness.

While contextual theories emphasize the changes to observation and research, contextual theories can also guide design. If interruptions are an impediment, then users might be given the option of blocking them. If usage outdoors is a requirement, then contrast setting or font sizes should be easily adjus tab le. If

114 Chapter 3 Guidelines, Principles, and Theories

collaboration with others is a high priority, then easy sharing of screens or tex­ ting should be possib le.

A taxonomy of mobile device applications could guide innovators:

• Monitor blood pressure, stock prices, or air quality and give alerts when normal ranges are exceeded.

• Gather information from meeting attendees or rescue team members and spread the action list or current status to all.

• Participate in a large group activity by voting and relate to specific individuals by sending private messages.

• Locate the nearest restaurant or wa terfall and identify the details of the current location.

• Capture information or photos left by others and shn.re yours with future visitors.

These five pairs of actions could be tied to a variety of objects (such as photos, annotations, or documents), suggesting new mobile devices and services . They also suggest that one way of thinking about user interfac es is by way of the objects that users encounter and the actions that they take (Robinson et al., 2015). A more ambitious use of mobile devices is to aggregate information from thou­ sands of cellphones to determine where there is highway congestion or which rides at an amusement park have the longest waiting lines.

3.4.4 Dynamic theories A key aspect of macro-HCI is how users evolve over weeks and months, espe­ cially as they move from novices to experts, from new customers to frequent buyers, or from readers of Wikipedia to active collaborators or administrators. These theories address design for evolutionary development of skills mastery, behavior change, reputation growth, and leadership capacities.

Dynamic theories owe much to the theories of adoption or innovation diffu­ sion (Rogers, 2003), which include five attributes:

1. relative advantage: faster, safer, more error free usage, or cheaper

2. compatibility: fitting for users' need, consistent with existing values

3. trial-ability: availability to experimen t with innovation

4. observabili ty: visibili ty of innovation to others

5. less complexity: ease of learning and use

These attributes lead to macro-HCI design guidelines, such as suggesting specific user-interface features, combining features to make some more visible than others, and providing informative feedback to users about their usage his­ tory. Other macro-HCI design guidelines will suggest ways of training users about features (informing tllem about new features), rewarding them for suc­ cesses (showing their progress in reading a book or their score in a game), and

3.4 Theories 115

sharing their progress with others (notifying friends about an exercise achieve­ ment or business associates about a price change).

Dynamic theories deal with long-term (weeks or months) changes in behav­ ior for health (smoking cessation, diet, exercise, or performance in memory games) or education (completing an online course or demonstrating increased familiarity with a body of knowledge). A large category of dynamic theories cover customer loyalty plans that encourage increased commitment, such as awards from restaurants, airlines, or hotels. These carefully designed programs have multiple award levels, such as bronze, silver, gold, and platinum, with carefully chosen benefits to encourage increased activity.

Behavior change by badge awards and loyalty programs will become increas­ ingly important because of the growing data sources about what works and wI-1at doesn't. The remarkably focused and personalized ways of persuading users and raising motivation will dramatically increase the possibilities for designers who understand whe11 personal recognition, social rewards, commu­ nity awareness, and financial compensation are most effective.

Dynamic theories are strong among designers of onliI1e communities and user-generated content sites. They know that users often move through stages as they gain confidence and a greater sense of responsibility for quality. There are many paths, but a study of Wikipedia contributors (Bryant et al., 2005) sug­ gests at least these stages: (1) reader of articles related to personal interests, (2) fixer of mistakes and omissions in familiar topics, (3) registered user and caretaker for a collection of articles, (4) author for new articles, (5) participant in community of authors, and (6) administrator who is active in governance and fuh1re directions.

Following these results, the Reader-to-Leader Model described how to design user-interface and social engagement features to promote movement through these stages over a period of weeks or months (Preece and Shneiderman, 2009). At early stages, there are user-mterface design guidelines, such as highlighting key features and valuable content, and social engagement design guidelines, such as encouragement from friends, family, and respected authorities. At later stages, there are user-mterface design guidelines, such as visible recognition for contributions, and social engagement design guidelines, such as promoting empathy, supporting mentoring, raising trust, and facilitating conflict resolution.

Macro-HCI theories also promote the idea that user interfaces have profound societal effects with positive outcomes such as increased social communication, safety, or health awareness and negative outcomes such as undermining concen­ tration, invading privacy, or exposing users to hackers. Visionaries see user inter­ faces as shaping personal processes of mindfulness, reflection, or empathy and community processes of civic participation, democratic sharing, or conflict reso­ lution (Bell and Dourish, 2011; Nelson and Stolterman, 2012; Calvo and Peters, 2014). At a grander scale, macro-HCI dreamers believe that better user interfaces and user experiences can support international development, improved health­ care, environmental preservation, and peaceful dispute reconciliation.

116 Chapter 3 Guidelines, Principles, and Theories

Practitioner's Summary

Design principles and guidel ines are emerging from practical experi­ ence and empirical studies. Managers can benefit by reviewing available guidelines documents and then constructing local versions. These docu­ ments record organizational policies, support cons istency, and record the results of practical and experimental testing. Guidelines documents also stimu late discussion of user-interface issues and help train new design­ ers. More established principles-such as recognizing user diversity, striv­ ing for consistency, and preventing errors – have become widely accepted, but the y require fresh interpretation as technolog y and applications evolve. Automation is increasing for many tasks, but preserving human control is still a beneficial goal.

Micro-HCI and macro-HCI theories are being validated and refined to clarify the desigi1 implications. For expert users with established sequences of actions, predictive models that guide designers to reduce the time required for each step are valuable. For novel applications and novice users, clarifying task objects and actions (for example, songs and albums that can be played or added to play lists) and promoting consis ten cy can lead to easily learned designs that promote user confidence. For every design, extensive testing and iterative refinement are nec­ essary parts of the development process.

Researcher's Agenda

The central problem for human-computer-interaction researchers is develop­ ing adequate micro-HCI and macro-HCI theories. Traditional psychological the ories must be extended and refined to accommodate the complex human learnin g, memory, and problem solving required in user interfaces and user experiences. Useful goals include descriptive taxonomies, explanatory theories, and predictive models. When predictions can be made for learning times, per­ formance speeds, error rates, subjective satisfaction, or human retention over time, designers can more easily choose among competing designs.

Theories in human-computer interaction can be grouped into five families: those that focus on design by levels, stages of action, consistency, con textual awareness, and evolutionary dynamics. Theories can be useful even if they are narrowly focused on a specific task, such as choosing a video from a database of millions of videos . Even more powerful are theories that apply to diverse tasks such as web searching, on line reviewing, or encour aging comm unjt y participa­ tion. Applied research problems are suggested by each of the hundreds of design

Discussion Questions 117

principles or guidelines that have been proposed. Each validation of these prin­ ciples and clarification of the breadth of applicability is a small but useful contri­ bution to the emerging mosaic of human performance with interactive systems.

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions.com / shneiderman

Many websites include guidelines documents for desktop, web, and mobile device interfaces and recommendations for universal usability strategies to accommodate users with disabilities or other special needs. Theories are pro­

liferating, and the web is a good place to keep up with the latest ones from major developers and sources promoting universal usability:

• Apple Human Interface Guidelines: http://developer.app le.com • Microsoft Windows User Experience Interaction Guidelines:

https://msdn.microsoft.com

• World Wide Web Consort ium (W3C) guide lines: http://www.w3.org/TR/WCAG20/

• Interaction Design Foundation Encyclopedia covers theories: https://www. i nteractio n-desig n.org/

Debates over hot topics can be found in relevant biogs and newsgroups,

which are searchable from many standard services such as Goog le or Bing.

Discussion Questions

1. Give a brief explanation of the Eight Golden Rules of Interface Design. State an example you have seen on a device, computer interface, or web site that ,riolates tho se rules.

2. Don Norman sugges ts organizing screens and menus functionally, design­ i11g commands and menu choices to be distinctive, and making it difficult for users to take irreversible actions. Norman also says to provide feedback about the state of the interface (e.g., changing the cursor to show whether a map inter face is in zoom- in or select mod e) and designing for cons istency of actions (e.g., ensuring that Yes/No buttons are always displayed in the same order). State one example you have seen where you know these rules have been vio lated . Although this is crucial to a user interface's success, suggest why there may be challenges to implement some of Norman's guidelines.

3. Clarify the difference among guidelines, principles, and theories.

118 Chapter 3 Guidelines, Principles, and Theories

4. What are some of the techniques that can be used to get the user's attention? Why is it important to exercise caution when using these techniques?

5. What are the stages of forming explanatory theories as suggested by Don Norman?

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