From an obituary of John Karlin by the excellent New York Times writer Margalit Fox, a passage about the psychologist who brought behavioral sciences to product design during his tenure at Bell Labs:

“By all accounts a modest man despite his variegated accomplishments (he had a doctorate in mathematical psychology, was trained in electrical engineering and had been a professional violinist), Mr. Karlin, who died on Jan. 28, at 94, was virtually unknown to the general public.

But his research, along with that of his subordinates, quietly yet emphatically defined the experience of using the telephone in the mid-20th century and afterward, from ushering in all-digit dialing to casting the shape of the keypad on touch-tone phones. And that keypad, in turn, would inform the design of a spate of other everyday objects.

It is not so much that Mr. Karlin trained midcentury Americans how to use the telephone. It is, rather, that by studying the psychological capabilities and limitations of ordinary people, he trained the telephone, then a rapidly proliferating but still fairly novel technology, to assume optimal form for use by midcentury Americans.

‘He was the one who introduced the notion that behavioral sciences could answer some questions about telephone design,’ Ed Israelski, an engineer who worked under Mr. Karlin at Bell Labs in the 1970s, said in a telephone interview on Wednesday.”