Elmer and Elsie (ELectroMEchanical Robot, Light-Sensitive) were two electronic robots that were built in the late 1940s by neurobiologist and cybernetician William Grey Walter. They were the first robots in history that were programmed to "think".[1] Elmer and Elsie were often labeled as tortoises because of how they were shaped and the manner in which they moved. They were capable of phototaxis which is the movement that occurs in response to light stimulus. [2]