What is good design? Bill Moggridge states that:
“good design has always been concerned with the whole experience of interaction” (Moggridge, 1999)Outwardly design is concerned with aesthetics, experience, the experience of using a product, of interacting with an object, product, service, or system of products and service. Inwardly design is also concerned with cost of materials, complexity of assembly, maintainability of modules and the whole product, lifetime, cost of operation, manufacture, distribution, delivery and return systems. The inward and outward aspects of design are tightly interrelated but further complicated (beneficially it turns out) by user involvement in the development process. User involvement in development is now recognized as one of the key success factors for high tech design and systems implementation (Leonard-Barton, 1988, Kraft and Bansler, 1994, Bødker et al., 2004, Grudin and Pruitt, 2002). User involvement is beneficial, in part at least, because both user understanding and design objects can be adapted throughout the development process (Leonard-Barton, 1988).
The quest for design should be tempered by the various problems 'improvements' produce. The search for an optimal solution is often an unnecessary diversion. Indeed an optimal solution will typically optimize according to a narrower set of criteria than is practical or desirable in the general situation. As Hamilton comments on designing and deploying internet-scale services “simple and nearly stupid is almost always better in a high-scale service” (Hamilton, 2007). In Hamilton’s case he recommends optimizations should not even be considered unless they offer order of magnitude or more performance improvements.
The ultimate measure of success for high tech design is for the product to become a seamless aspect of the user environment; to become simply, a tool for use, ready-to-hand.
“We need to be able to rely on an infrastructure that is smoothly engineered for seamless connectivity so that technology is not noticeable.” (Moggridge, 1999)Put another way, design succeeds when it disappears from perception.
Good design ‘lends itself to use.’ With physical objects the designer works within the constraints (and possibilities) of materials and space. The user’s embodied capability and capacity influences the size, shape, and apperance of a ‘use’ object. Physical design works with material affordance and constraints. Designers make use of experiential and cognitive cues such as ‘mapping’ and ‘feedback’ to achieve their goals (Norman, 2002). These approaches work because users form mental models or theories of the underlying mechanisms employed in mechanical objects. Indeed users actively look for such cues when confronted by a different or a new object for use. The effectiveness of cues, to translate designed performance into viable user mental models, translates in turn into effective object interaction; 'good design lends itself to use'. Good design is evident by the availability of a ‘clear mental model’ (Moggridge, 2006) or metaphor for a system. An effective mental model builds seamlessly into a coherent consistent ‘system image’ (Norman, 2002). A compelling system image is another strong indicator for successful system use. However digital media, virtual goods and computer based high tech systems pose a unique set of problems as a consequence of the break between an individual's knowledge of the physical world (intuitive, embodied, physical and temporal) and the computational world of digital objects.
“What do you get when you cross a computer with a camera? Answer: A computer! (Cooper, 2004)Microprocessor based goods and computer mediated virtual environments can made perform in apparently arbitrary or idiosyncratic ways, what Alan Cooper terms ‘riddles for the information age.’ (Cooper, 2004) In essence, by crossing computers with conventional physical products subsequent hybrid products work more like computers than their physical product forebears . In the past physical-mechanical elements often constrained design implementation whereas digital designs can in general overcome the constraints of electro-mechanical mechanisms. This break is both empowering and problematic. Empowering because it enables the designer to achieve things impossible with physical-mechanical elements alone, but problematic because while the 'back-end' digital design may conform with an architectural view of the technology (is architecture simply another way of saying the developer's implementation model) the outward appearance and behaviour available to users may be manifest in quite different ways. Mental model thinking can be problematic because, while the design implementation model may be self-consistent and behave logically according to its own rules, the implementation rules will appear be obscure, be overly detailed, or unintuitively linked to performance.
This break between implementation model and the user’s mental model is significant and necessitates a new language for describing and designing digital systems. While digital systems must obey their own (necessary) rules, the presentation of a system to the user should be designed with the user in mind. Taking his cue from physical goods design Don Norman suggests that a well designed microprocessor or computer-based system should still present its possibilities in an intuitive way (Norman, 2002). It should give the user feedback, allow the user to correct performance and offer a coherent ‘mental model’ to enable the user to understand and learn the product through use (Cooper et al., 2007, Norman, 2002).
The design of digital interaction can be thought of as spanning four dimensions (Moggridge, 2006). One dimensional linear or textual representations such as text, consoles, voice prompts etc. Interactions building on two dimensional visual or graphical renderings; layouts that juxtapose graphical elements or that depend on spatial selection and use/interaction in a two dimensional field . Third dimensional fields that make use of the third spatial axis depth , where depth is actually employed rather than simply mimicked through perspectival representation (e.g. as a backdrop to essentially 2D interaction). The forth dimension is most often thought of as time , meaningful temporal sequences and flows of interaction (rather than simply consuming a recording or animation). Temporal interaction may be applied to the preceding dimensions and involve complex interaction choreographies that are built up over time to achieve some goal.
- 1D interactions are employed by command line driven computing environments.
- 2D interactions are employed by typical applications and PC operating systems.
- 3D interactions are employed in immersive gaming environments.
- 4D interactions may be mode shifts in application interface, queries applied to data, different application states.