References: Lutz, M. C., & Chapanis, A. (1955). Expected locations of digits and letters on ten-button keysets. Journal of Applied Psychology, 39, 314-317. Deininger, R.L. (1960). Human factors engineering studies of the design and use of pushbutton telephone sets. Bell System Technical Journal, 39. 995–1012. How should we design keypads for most efficient human use? In 1953 Bell Telephone Laboratories wanted to move from the circular dial to a keypunch dialing system. Wisely, they hired human factors psychologist, Alphonse Chapanis to determine how the numbers should be arranged. Possibilities could have included numbers 1 to 10 arrayed in circles, semicircles, diagonal slashes, with the numbers ascending or descending. Chapanis and lab assistant Mary Lutz first wanted to find out where people expect to find numbers and letters on keys. They asked 300 participants to place numbers and letters on the keys according to where they thought they should be. For all six different configurations of keysets, people overwhelmingly preferred numbering arrangements where numerals increase from left to right and from top to bottom. Bell Lab’s engineer R. L. Deininger’s follow-up research showed that “these most preferred arrangements tended to be best in terms of performance.” Chapanis’ and others’ Ergonomic research (that designed for human ease) pinpointed why B-17 bombers kept crashing on runways, improved cockpit safety, pioneered the design of video- and tele-conferencing systems, studied intelligibility of digitized speech, and championed the user’s role in human-computer interaction. Human factors must be considered in all new inventions.

Written by Juanita N. Baker, Ph.D.