David Myers wrote: > Someone recently told me that psychological research contributed to the > display and ordering of red/yellow/green traffic lights. Does this ring a > bell with anyone? (It would be a cool example of the sort of thing we're > looking for.)
It was, I believe, a terrible *train* accident in the UK that had been caused by a colorblind engineer (who had confused a red signal with a green one) that led to the conventional ordering of signal lights: red on top and green on the bottom. In Quebec (and perhaps other places as well), traffic lights are now often spread horizontally across the road for better visibility. This has led to a new convnetion of red lights being square, greens round, and yellows diamond-shaped. Along similar lines, I read in some perception textbook a few years back (Margaret Matlin's?) that the white lettering on a green background often seen on road signs was a result of perceptual test that showed this to be the easiest combination to see. And while I'm on this topic, I heard a presentation a year or two ago by the editor of _Annals of the History of Computing_ (whose name escapes me at the moment) about Charles Babbage, who is best known for his work in the 1820s and 1830s on mechanical forerunners of the computer -- the Difference Engine and the Analytical Engine. His original aim in constructing the machines was to produce error-free mathematical tables (in order to increase industrial efficiency, which was his obsession), and so at one point he conducted (what we today would call) psychophysical experiments with virtually every color of ink on virtually every color of paper under different lighting conditions (which of course would have been a serious issue in the early 19th-c. -- lanternlight, candlelight, sunlight) to see which combination enabled clerks to locate the correct number in a table most quickly. The multicolored tables he used are now in an archive in Edinbugh, as I recall. Regards, -- Christopher D. Green Department of Psychology York University Toronto, Ontario, Canada M3J 1P3 e-mail: [EMAIL PROTECTED] phone: 416-736-5115 ext. 66164 fax: 416-736-5814 http://www.yorku.ca/christo/ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
