A pioneer in human factors engineering, Karlin undertook empirical research on the usability of numerical input systems and the capacity of people to recall digits. Karlin's design, with the "1" in the upper left position instead of the lower left (as on calculators), has been adopted on a wide array of devices, from ATMs to medical equipment.
The son of grocers, Karlin was born in Johannesburg, South Africa. He studied at the University of Cape Town, earning a bachelor's degrees in music, philosophy, and psychology, and a master's in psychology. At the same time he was a violinist with the local symphony orchestra and string quartet.
During World War II Karlin conducted research on psychoacoustics for the United States military. He joined Bell Labs afterwards, becoming the first staff psychologist there. He successfully argued for the foundation of its Human Factors Engineering Department in 1947, and was promoted to head it in 1951. He remained at Bell Labs until his retirement in 1977.
Karlin was married twice, and had two children, one of whom predeceased him, and three stepchildren.
- Fox, Margalit (February 8, 2013). "John E. Karlin, Who Led the Way to All-Digit Dialing, Dies at 94". The New York Times. Retrieved February 9, 2013.