In an essay entitled "The Plastic Goblet"  by graphic design educator Lorraine Wild, graphic design was likened to a "goblet" from which readers "drink" the content contained within. As we all know, although wine tasted from a paper cup is no different than that tasted from crystal stemware, the latter's user experience is typically better. Wild's point was that although good design cannot improve the content it presents, it can make the content more accessible, pleasurable, and easier to consume. Like Marshall McCluhan's equation of medium and message, the real user benefit lies in the marriage of communication design and content. This relationship between form and its subject also exists between design and technology, as eloquently portrayed in Zen and the Art of Motorcycle Maintenance .
Wild's essay came to mind after reading Aaron Marcus's "Dare We Define User-Interface Design?" , perhaps because Marcus's definition of user interface reminded me of the goblet metaphor. Marcus presents a detailed definition of the term user interface, including a thorough definition of its five elements: metaphor, mental model, navigation, interaction, and appearance. Over the years I've been increasingly puzzled about these elements because, as a user-interface designer, I find myself and my peers involved in other issues, beyond those covered by this definition, such as specification of a product's information (content and data) and functionality. From a graphic designer's viewpoint, perhaps it makes sense to see the world as being full of information and functionality in need of adequate containers or vehicles for delivery to users. Although I consider the specification of information and functionality a design activity, should I call this activity by another name? Or, am I not a user-interface designer, but something else?
Over the years, several terms other than user-interface design have gained popularity. Coined by design practitioners in an effort to better describe what they do, terms such as interaction design, information architecture, and user experience design are used as near-synonyms to user-interface design. According to Marcus, these terms have been vaguely defined and serve to "muddy (the) conceptual waters" of the CHI community's ability to understand and describe what CHI practitioners do. What explains the spread of these alternative terms? Are the proponents of these new terms ignorant or just opportunistically attempting to distinguish themselves? Or are these new terms relevant and useful to the rest of us?
Although I resist fads, I find myself and others using these other terms in professional practice, and they are widespread in industry literature. I support the use of clear, standard terms to clarify professional discourse, and for the most part, I believe that less is morethe fewer and clearer the terms, the better. I also think that quibbling over definitions can become a waste of time. Nevertheless, believing that language use is a sign of latent forces at play, I asked myself what these alternative terms mean, why they exist, and most important, are they useful and worthy of being kept? At the very least, I stood to gain insight into what to call what I do as a professional.
From a lot of thought and personal experience, and encouraged by Marcus's call for alternative definitions, I propose a model for thinking about how the variety of emerging disciplines interrelate. This model is focused on digital product design, which I propose as a discipline to include the design of products that feature digital technology or software.
The need for a new way to describe the design of digital products emerged as a result of the growth and importance of (1) the Web; (2) custom, integrated hardware-software product platforms; and (3) the interdisciplinary teams who design the Web and those platforms. The Web has moved information, brand, user interface, and functionality into a seamless, unified experience. Handheld devices continue to blur the distinction between hardware and software, and multidisciplinary teams that collectively develop ideas and products are commonplace. Digital product design seems the most appropriate term to describe what is being done in this evolving environment.
The model places digital product design within the more general discipline of user experience design and subdivides it into the related disciplines of interaction design, information architecture, user-interface design, and what I refer to as appearance design. These disciplines overlap and contain each other, reflecting patterns I've noticed in the industry for naming job titles, roles, and activities. The model prescribes a structure and set of definitions that I find useful.
At the core of the model are five elements, adopted by Marcus and detailed in his article, for defining user interfaces. They are metaphor (what the user-interface resembles), mental model (its organization), navigation (finding and displaying), interaction (input and output sequences), and appearance (look and feel). In addition to these, I've added the elements of information (content or data the product has) and functionality (work the product can do) to support a more complete description of digital products. These seven elements overlap considerably and shift in importance from product to product. They are a powerful tool for designing and analyzing digital products because they break down products into subsystems that, although highly intertwined, can be independently evaluated and worked on. A plausible metaphor for them is the relationship of nervous, cardiovascular, skeletal, and related systems in animals.
The boundaries between disciplines in the model are necessarily vague. For example, the difference between interaction design and information architecture can depend on precisely how one defines the user-interface elements of mental model, navigation, and interaction. Where this dividing line is drawn is not as important as the awareness that the difference exists.
Figures 1 and 2 show how several disciplines similar to user interface are interrelated. Figure 1 maps the disciplines to the key layers in distributed software architectures. Figure 2 maps the disciplines to the seven elements of digital product design and goes beyond them to depict the larger arena of experience design.
As Figure 2 shows, user experience design involves many additional potential elements, which perhaps explains the amount of effort and interest being invested in its definition and adoption as a discipline . Note that although this model proposes a set of disciplines, the disciplines can readily be correlated to and used as job titles. However, the model does not suggest that if your job title is interaction designer, for example, that you then cannot or should not design appearances. Rather, it is to say that if you are designing appearances, you are practicing appearance design and not interaction design, regardless of your job title. Its intent is not to proclaim that user experience designers, for example, are qualified to do all of what the other disciplines do and more, or that packaging and training have no interaction aspects. Rather it is to convey the comparative breadth of user experience design beyond the overt use of digital products.
In this section I supplement the figures by defining each discipline according to the elements they address and describe how the disciplines interrelate. I'll start with the most narrowly focused of the disciplines and move to the more general and inclusive.
Appearance design determines the surface form of a digital product and is typically driven by the results of information architecture or interaction design. It makes the product appear to the user in a way that supports the product brand and appeals to the user's taste; it also ensures the usability of low-level product issues such as legibility and readability of typography and image fidelity. Appearance design is commonly referred to as visual design because of the overwhelming prevalence of visual communication in digital products. However, appearance design is general enough to include sound and other perceptual channels.
The practice of using skins or shallow appearance facades in which to clothe products represents the trend of appearance variation and mutability. Primarily expressed through alternatively styled graphic design, branding, and sound treatments, skins economically represent identical functionality and logic in multiple brandings and flavors to appeal to a variety of market segments and fashion tastes. There is a large community of skilled appearance designers who can adapt an interaction design specification and design a readily-applied, distinctly-styled product skin. Product architectures that isolate the presentation layer make this practice easier.
Information architecture can be seen as information design with the added dimension of interactivity.
Information architecture focuses on the organization and taxonomy of information networks. Often consisting of writing, editing, and design skills, information architecture determines what content and data is included, where it resides, what it is called, how users find and access it, and to a certain degree, how it appears in a display. It involves primarily the organizing and naming of things and ensures that users find what they want without getting lost or distracted while navigating.
Information architecture is useful to describe work done involving the elements of information, mental model, and navigation. The reference to architecture reflects what is often a complex task where the variety of possible routes through information structures creates the sensation of traveling through built 3-D spaces.
Richard Saul Wurman is widely credited for coining the term information architecture. It gained popularity in the effort to organize large Web sites containing much content but little interactivity and grew out of the earlier disciplines of information design and information visualization.
Information design generally refers to the design of two-dimensional, graphical, highly structured, rational, nonlinear presentations of facts. Information visualization is a more specific variant that focuses on more abstract, graphical/spatial, interactive information displays.
Examples of information design include charts, graphs, tables, instructional aids, and large bodies of reference material. Information architecture can be seen as information design with the added dimension of interactivity.
Interaction design, along with user experience design, refers to the design of events or phenomenathe invisible aspects of products as opposed to their form. Interaction design's focus on product use and behavior versus on the product itself (as with appearance design, information architecture, and user-interface design) reflects how it differs from these disciplines. Interaction design specifies the capabilities a system must have to allow a user to interact with it to complete a process. Because processes can have multiple paths and outcomes, individual interactions and user experiences are not designed; rather, they are enabled according to the design of the system's capabilities and limitations. In this sense, interaction design is about design for interaction versus design of interaction.
Interaction design describes work involving the elements of metaphor, mental model, navigation, and interaction. It differs from information architecture in that it focuses less on content and surpasses the choosing and organizing of information to consider a greater variety and complexity of user workflows and use cases. For example, the complexity and difficulty of interaction design increases sharply when users are provided with capabilities like sophisticated authoring or editing to files or databases, highly mutable products, and alternative input-output devices.
Interaction design is quite similar to user-interface design in that the most relevant aspects of user interfaces are often their interactive capabilities. Interaction design is a specialty within user-interface design, de-emphasizing the appearance element in favor of the logic and planning involved in providing functionality in a form that is understandable and effective.
Interaction design is necessary for teams that have analysts and appearance designers but need to convert requirements into product concepts, structures, representations, and specifications. The product appearance and coding efforts can then be based on the interaction design specification.
The user interface delivers a product's human factors requirements (requirements that call for interaction with people), including both ergonomics and aesthetics. It is the part of the product (hardware and/or software) that the user perceives and must deal with. Conceptually, a user interface is a veneer for a product in a similar way that an appearance design is a veneer for a user interface.
User-interface design involves the elements of metaphor, mental model, navigation, interaction, and appearance. All products, not just digital ones, have user interfaces. For example, a printed poster has a user interface. In fact, it is almost pure user interface. It needs to be seen, read, understood, and responded to. The reader cannot do anything to the poster, so there is no physical interaction between posters and their audience (unless you include vandalism). The poster does interact with roles other than the audience, for example, the poster hanger. The poster must be economically postable. Posting involves human factors and, thus, is a part of a poster's user interface. Banks have user interfaces, which in the past consisted primarily of a building that you walked into, a line you waited in, and a person behind the counter who did things for you (basic mode). If the task was too complex, you switched to expert mode, and talked with a better-dressed person behind a desk who also did things for you. Now, automated teller machines are replacing basic mode and other systems are replacing expert mode.
"User interface" is an engineering term that does not orient industry outsiders to the essence of design.
User-interface design is losing its usefulness in high-technology professional practice for several reasons. First, it is both too broad and too narrow. By referring to all products, it does not necessarily refer to the technology industry. It is also too specific to refer to the most relevant unit of value, which is a digital product as a whole. Second, as a job title, it often refers equally to both engineers and designers. In some cases it refers to roles assigned strictly to engineer or build user interfaces and other times to roles assigned to design and engineer or build. The latter is often due to budget constraints that assign the entire user interface to one person, stretching her thinly across disciplines and reducing her ability to develop and use best practices. With user expectations for usability on the rise, projects staffed in this way will increasingly fail. Third, as a result of the previous reasons, user interface does not correlate well with job titles or roles on project teams. It is too broad a discipline for an individual to effectively cover and too narrow to wholly address issues on the product level. Finally, user interface is an engineering term that does not orient industry outsiders to the essence of design. By comparison, interaction design, experience design, and information architecture leverage more commonly understood metaphors. This tends to accelerate their understanding, appeal, and acceptance.
Digital Product Design
Digital product design, mirroring its manufacturing-based namesake product design, is a discipline that conceives, prototypes, and specifies a complete, working product that features digital technology. Because of the unique properties of digital products, they are typically set apart from analog products in discussions of design and development practice . The discipline includes user-interface design (metaphor, mental model, and so on), with the additional critical dimensions of information and functionality. In traditional processes, its goal is the complete specification of and tooling for what is to be built and marketed, including both hardware and software, typically excluding what is traditionally known as software development. Software development in this process equates to the manufacturing or construction phases of manufactured products and architecture . In agile processes , including extreme programming, the design effort is all but inseparable and indistinguishable from the development effort. Although I believe that digital product development is perhaps a more useful term, in this article I use design instead to be consistent with other discipline terms.
Digital product design is an important discipline because it brings together the technical capabilities of a product (its functionality), the information to be provided (content or data), and the means with which these elements are presented to the user (the five user-interface elements). This level of consideration allows a more comprehensive specification of the product to be delivered, and how it will be experienced, than is possible with user-interface design.
Participants on a digital product design (development) team can include any roleincluding researchers, analysts, interaction and appearance designers, and technologiststhat contributes to determining what is to be built and how.
User Experience Design
User experience design includes all elements involved with the design of digital productsand potentially many more depending on the scale of the project. Archetypical user experience design projects include highly immersive, multimedia, and spatially rich products like theme parks, restaurants, exhibits, retail stores, and urban environments. Because user experience design is more elusive to define than the previous terms, I do so with several statements below.
User experience design is:
- The process of specifying the messages, tools, services, people, scripts, and environments to support users in their efforts to carry out their intents.
- The process of specifying how users are treated by the products, messages, people, environments, smells, tastes, and so on, that they encounter while subscribing to a brand.
- An approach that focuses on the results of product consumption versus on the product itself.
- The design of something you can do, rather than something done to you.
- Product development elevated to the scale of brand.
- A design effort that includes the connections and relationships between designed artifacts versus the design of just the artifacts themselves.
- What designers say they do when they are not sure how to describe what they are designing.
All products used by people are experienced, and the experience of using a product is dominated by its design. Therefore, user experience design is somewhat redundant. Using user experience design to describe any non-engineering design activity is technically correct, although essentially impractical if a more specific term is suitable. If you design banner ads, you can say you are a user experience designer because viewers "experience" your ad. But does this really clarify what you do?
Perhaps the term's popularity is a response to the fact that, in today's popular lexicon, design is losing its reference to complex products. For example, a recent issue of The New York Times Magazine, comprehensively titled "Design 2002," is primarily about fashion and image . This trend is forcing designers of complex and highly interactive products to call themselves architects (architect is starting to mean "designer of complex things") and designers of multimedia meaning or event systems to call themselves experience designers.
Perhaps we need user experience design to refer to design that is neither engineering nor dominated by fashion or promotion. More specific than design, and more general than digital product design, perhaps user experience design can exist as a peer to engineering design to refer to the effort to determine the impact of products on people. The (of course, blurry and cross-linkable) hierarchy might appear as in Figure 3. Perhaps fashion design and advertising design are part of user experience design....I'm not sure. They play a part in user experience, yet represent fundamentally different design motivations.
User experience design exists as a result of a number of trends. First of all, media types and user intents are being intermingled within products to form combinations that defy traditional design categories. In addition, the growth of contextual and behavioral user research, expanding competition, media convergence and consolidation, closer and more intricate connections between and collaboration of design, engineering, and business, and the digitization of increasingly complex activities have focused greater attention on the user experience of products and how to improve it.
At the end of the day, the names of our disciplines should be judged by how effectively they help us to collectively get our work done and add value to products and systems. The rapid expansion of the industry has created both specialty and aggregate disciplines, with their own set of best practices that need to be identified. The disciplines proposed in this model can help to guide professionals, product teams, corporate design departments, and educational institutions in their efforts to explain what they do and to prepare people and assign them to roles where they can be most effective.
How these disciplines correspond to job titles and claims of expertise needs to be based on particular contexts. The most obvious example might be a design organization in a product company. The department could be called User Experience Design. Department staff assigned to multidisciplinary product development teams practice digital product design, and other members could be assigned to corporate or product identity projects to practice branding or appearance design. If the product emphasizes information over interaction with the need for branding (like a news Web site), assign an information architect along with an appearance designer. If the product emphasizes interaction over information with minimal branding (like an expense reporting system), assign an interaction designer who has rudimentary appearance design skills. Job titles referring to digital product design or user experience design might be reserved for leadership positions.
For individuals or firms focusing on appearance design, it may make sense to claim to design for user experience while specializing in appearance (or visual) design. User experience distinguishes them from engineering and the specialty pinpoints their strength; likewise for firms specializing in interaction design or information architecture. Firms offering all these services could accurately claim to provide full-service digital product design. Firms that provide user-interface engineering and production could claim to provide digital product development and either downplay the user experience design moniker or claim it alongside engineering design. In reality, a veritable spectrum of competencies across all of these terms exists in the marketplace.
Of course, out of self-interest, individuals and organizations can call themselves whatever they want regardless of their expertise. In the long run, however, both internal and external design customers will learn to seek skill sets according to this model's pattern. At this point, representing oneself accurately will increase awareness and build credibility. And although individuals exist who can perform effectively in multiple disciplines, the growing knowledge base of conventions and best practices within each discipline will make hands-on, state-of-the-art practice across disciplines more difficult.
Although the model might seem to advocate separation of the disciplines into isolated specialties, it actually remains agnostic to issues of integration, collaboration, and specialization. Ideally, specialists work together to design a seamlessly integrated whole under a unified vision. However, market realities often dictate a more compartmentalized process or one that requires individuals to perform in multiple disciplines at once. These issues are subjects for articles of their own; the model intends to support all cases by merely providing a framework for describing the work to be done.
Because of role specialization, both information architecture and interaction design are recognizable, definable disciplines that play a significant role in today's industry. The concept of appearance design, although lacking an inclusive discipline name, is also an important role and is carried out by a variety of specialists. Digital product design, accelerated by the Web's interdisciplinary teams, evolutionary real-time release capability; and merging of content, technology, and brand represents today's more holistic efforts to develop products. User experience design perhaps represents the medium in which digital product designers swim, providing them with an umbrella differentiator from the engineering discipline on the one hand and the more conventional variants of fashion and advertising design on the other. Although more complex as a system of disciplines, I believe that having and using this set of terms makes industry wheels turn easier.
For those wanting to simplify industry terminology, the Design Discipline Model may seem to work in the opposite direction. It advocates more terms and validates claims to higher-level design efforts. Unfortunately user-interface design, the de facto term, cannot describe the variety of ways in which designers contribute to digital product development. Despite its academic purity, it encourages an unnecessary separation between a product's user interface and its other aspects and does little to clarify the assignment of design roles and outcomes. No other product category refers to the design of user interfaces, yet all categories have them.
User interface and Marcus's set of elements are an academic abstraction. They are valuable and relevant to specialists, but without serving a wider purpose in daily use, they will not spread outside a limited design community. Language evolves according to need, and it is natural for both specialty and aggregate disciplines to appear and be named in an industry growing and changing as rapidly as ours is. If these disciplines help us to not only design better goblets, but to affect the choice and quality of the wine as well, then they are valuable.
My final point is that in discussing what to call ourselves, we should not resort to protectionism or turf battles of who said what first. New terms need not compete with current terms and should not be perceived as a threat. We should choose words based on how well they work, and if calling our professional practice über-interface design achieves better results, we should be free (and encouraged) to do so.
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