Designing a usable interface can be challenging. One of the best ways to learn is to review interfaces and see where they deviate from convention. This

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

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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 offi