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-fact

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. ........ 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.