You may not know his name, but you know his work. John E. Karlin, who passed away in late January, essentially invented the touch-tone keypad. We take that ubiquitous input device for granted—it's on everything from cell phones to alarm systems to microwave ovens—but there was a time when that interface didn't exist, and no one knew what the "correct" design for quickly inputting numbers ought to be.
An industrial psychologist, Karlin was working for Bell Labs (AT&T's R&D department) in the 1940s when he convinced them to start a dedicated human factors department. By 1951 he himself was the director of Human Factors Engineering. In the late 1950s they sought a faster alternative to rotary dialing, and Karlin and his group developed the configuration we know so well today.
During the process they examined different options, of course. Aren't you glad we didn't wind up with this?
You might think Karlin simply took the calculator keypad and placed the smaller numbers up top. Nope—take a look at what calculators looked like at the time:
