atedwith minimumconfusion or error.Clock radios are often used in the dark,
with the user in bed and reaching overhead to grope for the desired control.
Thereforetheunithadtobeusableinthedarkbyfeelonly.Itwasnotsup-
posed to be possible to make a serious mistake by accidentally hitting the
wrong control. (Alas, many existing clock radios do not tolerate serious
errors—for example, the user may reset the time by hitting the wrong button
accidentally.) Finally, the design was expected to take into account real issues
in cost, manufacturability, and aesthetics. The finished design had to pass
muster with users. The point of the exercise was for the student to realize the
paradox of technology: added complexity and difficulty cannot be avoided
when functions are added, but with clever design, they can be minimized.
Notes
- Reprinted by permission of theWall Street Journal,(Dow Jones & Co., Inc., 1986. All rights
reserved. - W. H. Mayall (1979),Principles in design,84.
- The notion of affordance and the insights it provides originated with J. J. Gibson, a psychologist
interested in how people see the world. I believe that affordances result from the mental inter-
pretationofthings,basedonourpastknowledgeandexperienceappliedtoourperceptionofthe
things about us. My view is somewhat in conflict with the views of many Gibsonian psycholo-
gists, but this internal debate within modern psychology is of little relevance here. (See Gibson,
1977, 1979.) - D. Fisher & R. Bragonier, Jr. (1981),What’s what: A visual glossary of the physical world.Thelistof
the eleven parts of the sink came from this book. I thank James Grier Miller for telling me about
the book and lending me his copy. - Biederman (1987) shows how he derives the number 30,000 on pages 127 and 128 of his paper,
‘‘Recognition-by-components: A theory of human image understanding,’’Psychological Review,
94 , 115–147. - I thank Mike King for this example (and others).
- More complex systems have already been successfully built. One example is the speech message
systemthatrecordedphonecallsforlaterretrieval,builtbyIBMforthe1984Olympics.Herewas
arathercomplextelephonesystem,designedtorecordmessagesbeingsenttoathletesbyfriends
and colleagues from all over the world. The users spoke a variety of languages, and some were
quite unfamiliar with the American telephone system and with high technology in general. But
by careful application of psychological principles and continual testing with the user population
during the design stage, the system was usable, understandable, and functional. Good design is
possible to achieve, but it has to be one of the goals from the beginning. (See the description of
the phone system by Gould, Boies, Levy, Richards, & Schoonard, 1987.)
References
Biederman, I. (1987). Recognition-by-components: A theory of human image understanding.Psy-
chological Review, 94, 115–147.
Fisher, D.,&Bragonier,R.,Jr. (1981).What’s what: A visual glossary of the physical world. Maplewood,
NJ: Hammond.
Gibson, J. J. (1977). The theory of affordances. In R. E. Shaw & J. Bransford (Eds.),Perceiving, acting,
and knowing. Hillsdale, NJ: Erlbaum.
Gibson,J.J.(1979).The ecological approach to visual perception. Boston: Houghton-Mifflin.
Gould, J. D., Boies, S. J., Levy, S., Richards, J. T., & Schoonard, J. (1987). The 1984 Olympic message
system: A test of behavioral principles of system design.Communication of the ACM, 30,758–
769.
Mayall, W. H. (1979).Principles in design.London:DesignCouncil.
Norman, D. A. (1986). Cognitive engineering. In D. A. Norman & S. W. Draper (Eds.),User centered
system design: New perspectives on human-computer interaction. Hillsdale, NJ: Erlbaum.
442 Donald A. Norman