And when, not long afterward, the dial gave way to push buttons, new questions arose: round buttons, or square? How big should they be? Most crucially, how should they be arrayed? In a circle? A rectangle? An arc?
For decades after World War II, these questions were studied by a group of social scientists and engineers in New Jersey led by one man, a Bell Labs industrial psychologist named John E. Karlin.
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.
In 2013, the 50th anniversary of the introduction of the touch-tone phone, the answers to those questions remain palpable at the press of a button. The rectangular design of the keypad, the shape of its buttons and the position of the numbers — with “1-2-3” on the top row instead of the bottom, as on a calculator — all sprang from empirical research conducted or overseen by Mr. Karlin.
The legacy of that research now extends far beyond the telephone: the keypad design Mr. Karlin shepherded into being has become the international standard on objects as diverse as A.T.M.’s, gas pumps, door locks, vending machines and medical equipment.
Mr. Karlin, associated from 1945 until his retirement in 1977 with Bell Labs, headquartered in Murray Hill, N.J., was widely considered the father of human-factors engineering in American industry.
A branch of industrial psychology that combines experimentation, engineering and product design, human-factors engineering is concerned with easing the awkward, often ill-considered marriage between man and machine. In seeking to design and improve technology based on what its users are mentally capable of, the discipline is the cognitive counterpart of ergonomics.
“Human-factors studies are different from market research and other kinds of studies in that we observe people’s behavior and record it, systematically and without bias,” Mr. Israelski said. “The hallmark of human-factors studies is they involve the actual observation of people doing things.”
Among the issues Mr. Karlin examined as the head of Bell Labs’ Human Factors Engineering department — the first department of its kind at an American company — were the optimal length for a phone cord (a study that involved gentle, successful sabotage) and the means by which rotary calls could be made efficiently after the numbers were moved from inside the finger holes, where they had nestled companionably for years, to the rim outside the dial.
John Elias Karlin was born in Johannesburg on Feb. 28, 1918, and reared nearby in Germiston, where his parents owned a grocery store and tearoom.
He earned a bachelor’s degree in philosophy, psychology and music, and a master’s degree in psychology, both from the University of Cape Town. Throughout his studies he was a violinist in the Cape Town Symphony Orchestra and the Cape Town String Quartet.
Moving to the United States, Mr. Karlin earned a Ph.D. from the University of Chicago in 1942. Afterward, he became a research associate at Harvard; he also studied electrical engineering there and at the Massachusetts Institute of Technology.
At Harvard, Mr. Karlin did research for the United States military on problems in psychoacoustics that were vital to the war effort — studying the ways, for instance, in which a bomber’s engine noise might distract its crew from their duties.
