This is Part 1 of a pre-print draft of Chapter 3 from Smart Things: Ubiquitous Computing User Experience Design, my upcoming book. (Part 2) (Part 3) (Part 4) The final book will be different and this is no substitute for it, but it's a taste of what the book is about.
Last month I posted a draft of Chapter 1
Citations to references can be found here.
[Note: don't let the theoretical nature of Chapter 1 and this chapter give you the idea that the book is all theory. It's designed to be a practical tool for working designers, but I feel that a theoretical grounding is important to put the practical examples and advice in context.]
Chapter 3: Interaction metaphors
No simple analogical model is sufficient to completely explain the operation of a computer system. Computer systems are too different from familiar, everyday non-computational systems.- Halasz and Moran, "Analogy Considered Harmful," 1982
First of all, we made the screen layout resemble a desktop; displaying pictures of objects you'll have no trouble recognizing. File folders. Clipboards. Even a trash can.- Apple Macintosh advertisement, Newsweek, 1984 Designing new technologies with unfamiliar interactions is a constant challenge in ubicomp user experience design. How can an object that may not be obviously computational communicate its capabilities without requiring enormous amounts of external documentation or training?
Mapping one category of ideas to another is the basis of linguistic metaphor, which The MIT Encyclopedia of the Cognitive Sciences (Wilson and Kiel, 1999) defined as a "class inclusion assertion." In this definition, a metaphorical comparison implies that two things belong to the same class of objects, even if the two things do not seem to share any directly comparable characteristics.
[Footnote: The MIT Encyclopedia of Cognitive Science (Wilson and Keil, 1999) gave the example of "my lawyer is a shark" as a linguistic metaphor. Metaphors are also not the only way to compare two objects. Marcus (1998) listed a number of non-metaphoric concepts that compare two sets of ideas. His list includes models, analogies, similes, metonymy, and synecdoche.]
Hence lawyers are sharks and love is a flower. Once established, a metaphorical relationship allows reasoning about an unfamiliar concept using what we know about the more familiar one. The details will not match exactly, and terrible analogies regularly surface (how does calling the Internet "a series of tubes" [Footnote: As per former US Senator Ted Steven's infamous June 28, 2006, description.] help us understand e-mail?), but metaphorical comparison can be a basis for reasoning when little is known. Going further, Lakoff and Johnson (1999) argued that cognition is entirely metaphorical. For them, abstract ideas can only be comprehended in terms of metaphors to concrete concepts, even when the metaphorical match is imperfect. For example, they write time is often characterized in terms of money. People talk about how much time something will take, or whether an activity will save time even though it is not possible to stockpile time or to trade it for goods or services as we might with money.
Metaphors have long been part of how we think about design. In 1923, the architect Le Corbusier famously wrote that "a house is a machine for living in." It was a statement crafted to evoke the architectural capabilities of the new materials and engineering techniques of the twentieth century, even as it implied that building dwellers are more like cogs in the machine than operators of it. In the 1970s and early 1980s, another famous metaphorical comparison of life inside buildings to the operation of machines became a key factor in popularizing personal computing.
Before the late 1970s and early 1980s, computers were largely controlled by typing words into command-line and "glass teletype" interfaces. Xerox PARC's office desk metaphor, popularized by Apple's Macintosh computer, made many capabilities of the computer system (such as storing files in hierarchical directories) accessible through representations of familiar office objects (such as folders). This mapping proved very successful. Even though the onscreen objects did not behave exactly like their real-world counterparts -- no one keeps a stack of glass windows on the top of their office desk, for example -- evocations of familiar objects were more helpful than a command-line-based operating system in acquainting a larger audience with the capabilities of their personal computers. A machine, it seems, could be a house for living in. [Footnote: Thanks to Liz Goodman for this observation.]
The position of ubiquitous computing resembles that of computing before the 1970s: we have a palette of new technologies without metaphors to communicate their power or operation. If Lakoff and Johnson are correct, and reasoning is largely metaphorical, then people encountering these unfamiliar technologies will always rely on metaphors to interpret them. From a design perspective, then, it makes sense to discuss the kinds of associations new technologies could or should prompt. And it also makes sense to identify the metaphors designers consciously or unthinkingly employ. Just as it may be impossible to reason without metaphors, it also may be impossible to design without them. Design requires using tools skillfully, and metaphors are the tools of thought.
[Note: I am deeply indebted to John Lawler, whose "Metaphors we compute by" (1987) class at the University of Michigan's Residential College was fundamental to my thinking about how people interact with computers. I also thank Bruce Sterling for his review of an early draft of this chapter, and to Dan Saffer for giving me permission to reprint his guidelines for design with metaphor.]
Tomorrow: Chapter 3, Part 2: A Catalog of Ubicomp UX Metaphors