Design of Everyday Things [119]
3 See Schank & Abelson’s (1977) Scripts, plans, goals, and understanding or Goffman’s (1974) book Frame analysis, on social structures and conventions.
4 We had to overcome a number of technical problems to improve the mapping. The lights were already installed, and it was not possible to redo the wiring. We modified some light dimmers so that they could be used as controls for remotely located lights. The choice of electrical switches was also limited. Ideally, we would have made parts especially for our purpose. Still, the experiment has been remarkably successful. In this work, I relied heavily on the electrical and mechanical ingenuity of Dave Wargo, who actually did the design, construction, and installation of the switches.
5 The reason for the awkward location of the switch is cost. One designer wrote me: “I fought the good battle to get the on/off switch to the front of the terminal. I lost the argument both times. The hardware engineers costed the front mounted switch at about $10 (about $30 to the consumer), plus the potential for the power to contaminate some nearby circuits.” Those prices seem high to me, but this designer was speaking of professional equipment, where the terminal probably costs in the thousands of dollars. Here is the standard tradeoff of cost versus usability. What price are you willing to pay for usability? Does the cost really have to be that high? What if the switch had been designed to be on the front from the very beginning, as opposed to having to be moved after the rest of the layout had been completed?
6 Copyright 1987 by Consumers Union of United States, Inc., Mount Vernon, NY 10553. Excerpted by permission from Consumer Reports, Jan. 1987.
7 See Gaver (1986).
CHAPTER FIVE: To Err Is Human
1 InfoWorld, Dec. 22, 1986. Reprinted by permission.
2 See Sherry Turkle’s (1984) analysis in her book The second self The book is mostly about the impact of computers on people’s lives, especially on the children who have grown up with daily, continual contact with machines—the “hackers” of the world. Turkle also presents an analysis of the changes that information-processing views of the human mind have made to our interpretation of Freud. All around, it is an intriguing and important book.
3 Unless otherwise noted, all the examples in this section were collected by me, primarily from the errors of myself, my research associates, my colleagues, and my students. Everyone diligently recorded their slips, with the requirement that only the ones that had been immediately recorded would be added to the collection. Many were first published in Norman (1980 and 1981).
4 The term “capture error” was invented by Jim Reason of Manchester, England (Reason, 1979). Reason has written widely on slips and other mishaps. I recommend as a good review of his work the book Absent minded? The psychology of mental lapses and everyday errors (Reason & Mycielska, 1982).
5 Reason (1979).
6 A simple introduction to schema theory can be found in my book Learning and memory (Norman, 1982).
7 The best source of information about the connectionist approach is the two-book series Parallel Distributed Processing (Rumelhart & McClelland, 1986; McClelland & Rumelhart, 1986).
8 An important set of studies has been performed by Danny Kahneman and Amos Tversky (Tversky & Kahneman, 1973). Kahneman and Miller’s (1986) “Norm theory” applies a related set of ideas.
9 A standard objection to my claim that everyday tasks are conceptually simple—that they do not require extensive search and backtracking—is that perception and language are certainly everyday tasks, yet they violate these rules. I disagree.Yes, perception and language are certainly everyday tasks. But I do not believe they violate my argument. I argue that the key to conceptual complexity is whether or not backtracking is required: Is there trial and error? Are multiple paths investigated? I want to argue that none of these are required for everyday tasks, including perception and language.
The study of perception is