From the linked Wikipedia page:

“Theseus”, created in 1950, was a mechanical mouse controlled by an electromechanical relay circuit that enabled it to move around a labyrinth of 25 squares.[71] The maze configuration was flexible and it could be modified arbitrarily by rearranging movable partitions.[71] The mouse was designed to search through the corridors until it found the target. Having travelled through the maze, the mouse could then be placed anywhere it had been before, and because of its prior experience it could go directly to the target. If placed in unfamiliar territory, it was programmed to search until it reached a known location and then it would proceed to the target, adding the new knowledge to its memory and learning new behavior.[71] Shannon’s mouse appears to have been the first artificial learning device of its kind.[71]