The Digital Dial

The late John E. Karlin was little known but is well remembered for fundamentally changing the relationship between people and technology, reports Margalit Fox in The New York Times (2/9/13). Karlin was an industrial psychologist who came up with the shape and configuration of the touch-tone telephone keypad. “He was the one who introduced the notion that behavioral sciences could answer some questions about telephone design,” says Ed Israelski, who worked for Mr. Karlin at Bell Labs.

The rectangular shape of the keypad, the half-inch size and square shape of its buttons, and the idea of putting 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.” This research differed from other types of research in that it was based on observing people’s behavior and recording it “systematically and without bias.” It was “based on what users are mentally capable of.” The keypad is today “the international standard on objects as diverse as ATMs, gas pumps, door locks, vending machines and medical equipment.”

Before tackling the keypad, Mr. Karlin arrived at the “optimal length for a phone cord.” He did so by secretly reducing the length of his colleagues’ three-foot cords, an inch at a time, until they detected the difference. No one noticed until the cords were a foot shorter. Earlier, Mr. Karlin introduced the white dot in the center of the old rotary dial, which helped users when the numbers were moved from inside the finger holes to the rim outside the dial. Apparently, people needed to aim their finger at a target to dial efficiently. “The dot restored the speed.” John E. Karlin was 94.