What exactly do we mean by user-interface design? Apparently, it depends on who's asking, or who's speaking. Consider the following events.
Recently, Bill Moggeridge, a well-known product designer, acknowledged in a keynote address at Designing Interactive Systems 2002 (DIS 2002), a SIGCHI-sponsored design conference, that he, assisted by a fellow product designer, Bill Verplank, invented the concept of interaction design in the early 1980s. In his review of important contributors to this term that he never defined but which seemed to include much of user-interface design, he included a number of well-known user-interface researchers, as well as founders of Google, a successful Web-based information search service, and of Palm's mobile-device operating system. The term user interface almost never entered the discussions.
About a year ago, Alan Cooper, a well-known software designer (and inventor of a software language) announced in the keynote address of the Usability Professionals Association's annual conference, that he was the inventor of the concept of interaction design in the 1980s, a concept that he, too, never defined in his lecture but that seemed to include much of user-interface design. He also said that interaction design (thus, user-interface design) didn't exist until he brought it into being.
In recent publications of the American Institute of Graphic Arts and conferences that it has co-sponsored with SIGCHI, promoters of a concept called experience design have proposed that they are designing something larger than, different from, and more important than user-interface design. Attempts to define exactly what this term includes in the promoters' magazines, books, lectures, and conferences remain ambiguous thus far.
During a gathering to discuss the newly formed Institute of Design at the University of California at Berkeley, Arnold Wasserman, a well-known corporate product designer and strategist, praised the product design community for having been the first to emphasize usability rather than the human factors specialists' more narrow focus on ergonomic issues. In doing so, he appeared to overlook the typography and graphic design community's contemporaneous investigation of these same kinds of issues.
During the advent of the Web and the rise, then fall, of the DotComs, information architecture seemed to be the new term to describe much, but not all, of user-interface design. Note, however, that information architects, unlike their more established cousins, are not licensed to practice. (Certification for analysts and designers is a complex, thorny matter that I shall not address here.)
When I first began writing a user-interface design manual in the late 1970s, I was already aware that there was a topic of user-interface design. Shortly after that, CHI held its first conference. Today, product reviews in the Wall Street Journal and the New York Times comment regularly on user-interface design. Apparently, these critics, and presumably the general public, understand the term user-interface design.
What is going on here? Many reasonably well-educated and presumably well-meaning professionals seem to be forgetting history, rewriting history, and muddying conceptual waters rather than clarifying them.
It seems appropriate on the occasion of SIGCHI's 20th anniversary to consider how the profession defines itself, particularly in its "design" aspects. Of course, whether SIGCHI should undertake such an activity at all is debatable to some who worry about which professions are included and which are not. Others might say, let a thousand definitions bloom; the more the better.
I take a middle road in trying to be simple, clear, and consistent in defining the terms. Much is at stake in this conceptual turf battle. Around the world, institutions of higher learning are attempting to establish clear pedagogical objectives and curricula that present a coherent, inclusive view of user-interface design. More than 10 years ago, SIGCHI itself tried to describe a user-interface analysisdesigntheory curriculum for computer science departments. Now, many professions are involved in trying to define this complex, challenging topic.
Almost any practical term could replace user-interface design. However, without clear, consistent, agreed-on conventions, the terminology may confuse professionals, teachers, and students, further confusing or boring the general public, and not effectively reaching the business community. Some inappropriate terms may become conventions, which sometimes impoverishes distinctions.
For example, the computer industry, has unfortunately, obliterated much of the useful distinction of sign, icon, and symbol. The general semiotics term sign is casually equated with its subterms icon (representational, or "natural" sign) and symbol (abstract or conventional signs). In many professional situations of analysis and design, these distinctions are important to maintain. Alas, all of the small visual signs of user interfaces are now loosely called icons by professionals as well as the public.
Some of the organizations that have a stake in this process of defining user interface and design include the following:
- American Institute of Graphic Arts (AIGA)
- Association for Computing Machinery (ACM)
- ACM Special Interest Group for Computer-Human Interaction (SIGCHI)
- ACM Special Interest Group for Graphics and Interaction (SIGGRAPH)
- Human Factors and Ergonomics Society
- Industrial Design Society of America
- International Institute for Information Design
- Society for Technical Communication
- Society for Software Design
- Society for Software Psychology
You may have candidates to add to this list. Professionals of these and other organizations have considered one or more of these topics to be the appropriate term for essential design activities:
- Applied semiotics
- Computer-based communication design
- Computer-based theater design
- Computer-human interaction design
- Experience design
- Human-computer interaction design
- Information architecture
- Information design
- Interaction design
- Interactive media design
- Narrative design
- User-experience design
- User-interface design
- Visual design
If we are careful in our thinking, we should be able to translate from one paradigm to another, appreciating the various complexities and values.
Again, you may have additions to suggest. The terminology has always been fluid and subject to social, political, and technological shifts. Recall that manmachine interface (MMI) was changed to ungendered synonyms during the late 1980s and early 1990s and that multimedia became a redundant term by the late 1990s. The availability of virtual and augmented reality; mobile devices; wearable computers; and less-noticeable, ubiquitous computers have all caused theorists, teachers, and professionals to rethink their terminology and definitions. It is also possible that well-designed definitions may serve during many changes of technology, if the terms are well defined.
Here is what seems to me to be a reasonable approach to defining user-interface design.
First, we should acknowledge that human beings, to paraphrase the structural anthropologist Claude Levi-Strauss , are fundamentally tool- and sign-makers. As artifact makers, we are deeply connected to our wired-in capabilities; to personal emotional, cognitive, and spiritual needs and desires; as well as to our sociocultural constructs. We have been making clothes, hammers, and other physical tools for countless millennia. We also have been communicating through physical gesture, touch, sound, smell, and vision for eons. Tools enable us to change our physical environment. Written artifacts, including coins, parchment rolls, and walls, carry messages across space and time in a way physical gestures and speech cannot.
These aspects of the history of communication are worth mentioning, because the history of computers itself is closely enmeshed with the challenge to improve input and output techniques. What we are addressing essentially is not solely physical object design, but computer-mediated human-human communication.
User-interface design could be defined from the perspective of a tool, (physical object) or communication. Either way, both definitions would include interaction as a concept. However, it is important to appreciate the full meaning of user interfaces as communication artifacts. To call user-interface design interaction design misses some important points, as seems evident if one listens to proponents of interaction design.
In Designing Pleasurable Products , Patrick Jordan presents a property checklist for designing a power drill. The list includes many sensory attributes, functionality, and "interaction design," which is defined elsewhere as interaction sequences and protocols. The communication dimensions seem to be missing.
In the recent keynote lecture I mentioned earlier about the history of interaction design over the past 20 years, Bill Verplank mentioned that there is something else besides interaction design called media design, which is essentially an "expressive" activity. By "media," I understand such terms as broadcast television, video tapes, printed books, comic books, cinema, CDs, DVDs. In previous centuries, one would mention religious and governmental architectural sculptural friezes, documents, and monuments. As communication forms, according to the definitions of Moles , media convey information, persuasion, and aesthetics (some might add spiritual content). Definitions of media by interaction designers seem to view media as only expressive or aesthetic or persuasive communication, neglecting the long history of information-oriented visual communication design, with its close ties to graphic design, education, government, commerce, and technology.
Regarding "experience design," it seems that some graphic designers, media designers, Web designers, branding and business strategists, and others claim the design of the interactive experiences of a viewer, customer, visitor, resident, or reader. This claim seems a bit vague. What would architects of buildings or landscapes make of this? Would they not be one of the first to claim the design of interactive human experience? Those wishing to understand the work of experience designers might do well to consider the work of Disney designers, who do, indeed, control the total experience of visitors to Disney-fabricated environments .
What then are my proposed definitions? I have been refining them for many years, and I present them below in a short lexicon. This philosophical perspective emphasizes communication as a fundamental characteristic of computing, one that includes perceptual, formal characteristics and dynamic, behavioral aspects of how people interact through computer-based media. This approach acknowledges user-interface design more strongly as a set of communication design tasks but tries, also, to find places for product and architectural design. The intention has been to acknowledge the specific skills of many different artifact-design profesions. Sound designers, theater designers, graphic designers, and information designers often seem marginalized in the definitions that I have encountered. I have tried to formulate the definition of user-interface design in a manner that allows it to be inclusive, not exclusive. I have also tried to define terms so that they can survive the rapid change of platform technology. The eventual "disappearance" of computers and the rise of "smart" objects will always involve communication rituals. In some ways, we are back where we started 10,000 years ago with the exchange of three-dimensional tokens, but with many new magnificent twists in our computer-based media.
I hope you will find this lexicon useful. Others may propose different perspectives and terms. If we are careful in our thinking, we should be able to translate from one paradigm to another, appreciating the varying complexities and values. Discussing these world views and terminology is a healthy intellectual, professional exercise. I invite you to join the ongoing debate.
A Brief User-Interface Lexicon (of Canonical, Reserved Terms)
Appearance: Includes all essential perceptual attributes, that is, visual, auditory, and tactile characteristics. Examples include choices of colors, fonts, animation style, verbal style (such as verbose/terse or informal/formal), sound cues, and vibration modes.
Communication: The conveyance of information, persuasion, aesthetics (and, some would add, spiritual content) from one entity to others. Typically, people describe, explain, emote, praise, or ritually enact through their communications. The activity requires senders, receivers, messages, and media. The process assumes that some behavior indicates that the receivers have acquired the messages and understood them.
Information: One level in a hierarchy of organized content to be communicated. The levels of increasing complexity are: data, information, knowledge, and wisdom, described as follows:
- Data: Organized input from the senses
- Information: Significant patterns of organized data
- Knowledge: Significant patterns of organized information with action plans
- Wisdom: Significant patterns of organized knowledge plus real-world experience gained over time.
Information visualization: A special aspect of user interfaces, the means for communicating structures and processes, which may be shown in abstract or representational forms. Classically, these may be described as tables, forms, charts, maps, and diagrams. The list suggests an approximately increasing complexity of visual syntax. This term emphasizes visualization but is intended to include other sensory means to communicate information.
Interaction: Includes input-output techniques, status displays, and other feedback, both locally and globally. In the computer platforms of today, local examples include the detailed behavior characteristics of equipment, such as keyboards, mice, pens, or microphones for input; visual display screens, loudspeakers, or headsets for output; and the use of drag-and-drop selection and action sequences. Global examples include context issues, usage scenarios, and task activities at a larger scale.
Metaphor: Fundamental concepts  communicated via words, images, sounds, tastes, smells, and tactile experiences. In computer operating systems, metaphors substitute for collections or individual elements and help users understand, remember, and enjoy the entities and relationships of computer-based communication systems. Metaphors can be overarching or communicate specific aspects of user interfaces.
An example of an overarching metaphor is the desktop meta-phor that substitutes for the computer's operating system, functions, and data. Examples of specific concepts are the trashcan, windows and their controls, pages, shopping carts, chat rooms, and blogs (Weblogs, or Web-based diaries). The pace of metaphor invention, including neologismsthat is, verbal metaphor in-ventionis likely to increase because of rapid development and distribution, through the Web and mobile devices, of mutable products and services. Some researchers are predicting the end of the desktop metaphor era and the emergence of new fundamental metaphors.
Mental models: Structures or organizations of data, functions, tasks, roles, and people in groups at work or play. Examples of related versions of mental models are user models (which include concepts of personas, goals, needs, desires, roles, and the like), user cognitive models, user task models, and designer models. Mental models exhibit hierarchies of content, tools, specific functions, media, roles, goals, tasks, and so on. Some professionals speak of goal-oriented design, user-centered design, task-centered design. These orientations emphasize close analysis of varying mental models.
Navigation: Involves movement through the mental models, that is, through content and tools. Examples of user-interface elements that facilitate such movement include those that enable dialogue, such as menus, windows, dialog boxes, control panels, icons, and tool palettes.
Semiotics: The science of signs . Semiotics identifies four dimensions of "meaning" for information visualizations that communicate through "signs."
- Lexical: How are the signs produced?
- Syntactic: How are the signs arranged in space and time and with what perceptual characteristics?
- Semantic: To what do the signs refer?
- Pragmatic: How are the signs consumed or used?
User interface (UI): A computer-mediated means to facilitate communication between human beings or between a human being and an artifact. The user interface embodies both physical and communicative aspects of input and output, or interactive activity. The user interface includes both physical objects and computer systems (hardware and software, which includes applications, operating systems, and networks). A user interface may be said to consist of user-interface components. Reasonable synonyms for user interface include human-computer interface and human-human interface. This last term seems appropriate for an era in which computers themselves disappear, leaving only "smart" ritual objects and displays, such as "smart eyeglasses," "smart clothes" and "smart rooms."
User-interface components: metaphors, mental models, navigation, interaction, and appearance.
User-interface design: The general activity more properly should be called user-interface development, similar to software development. Design focuses on the synthesis stages.
User-interface development: User-interface development consists of these tasks undertaken in a partially parallel, partially serial, partially iterative sequence: plan, research, analyze, design, implement, evaluate, document, train, maintain, and recycle/replace.
User-Interface platform: The user-interface platform is the physical home of the user interface, that is of the hardware and software. Traditional examples include terminals, workstations, desktop computers, Web sites, Web-based applications, information appliances, and mobile and wireless devices. However, in general, the platform encompasses all physical products (consumer or professional) such as chairs, power drills, tea kettles, tape measures, and physical environments, such as rooms, buildings, and vehicles.
Aaron Marcus, President Aaron Marcus and Associates, Inc. Aaron@AMandA.com
Aaron Marcus (Aaron@AmandA.com) is president of Aaron Marcus and Associates, Inc., Emeryville, California, and New York, New York (www.AmandA.com). Mr. Marcus frequently lectures on user-interface design and has authored or coauthored four books on the topic.
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