Grey Walter's tortoises
Walter built two autonomous robots on two valves each that sought light, avoided obstacles and returned to a charging hutch.
Why it matters
Complex behaviour came out of very few parts, an argument against the idea that intelligent behaviour needs an intricate device.
Elmer and Elsie ran on three wheels with a photocell and a contact sensor. Walter observed behaviour that did not repeat and described it as a hint of free will. A later variant was trained on a conditioned reflex. The machines were exhibited at the 1951 Festival of Britain.