Science: Mouse with a Memory

In the Bell Telephone Laboratories at Murray Hill, N. J. lives a mechanical mouse named Theseus, the creature of Dr. Claude Shannon, Bell computer authority. It was named after the Greek mythological hero who went into the Cretan labyrinth and slew the Minotaur. But Theseus Mouse is cleverer than Theseus the Greek, who could not trust his memory but had to unwind a ball of string to guide him out of the labyrinth.

Bell Telephone’s labyrinth is about half as big as a desk top and is fitted with aluminum partitions which can be shifted around among 40 different slots. Theseus himself has only a mouse-shaped wooden body, three small wheels and whiskers of copper wire. Inside him is nothing but a bar-magnet. His brains are outside him, under the floor of the labyrinth. They are a complicated array of relays.

Dr. Shannon sets up the labyrinth in a pattern unfamiliar to Theseus. Then he places his mouse at an arbitrary point on the metal floor. At first Theseus does not behave very intelligently. He blunders around, bumping his copper whiskers against the aluminum walls. When he hits an obstacle, he turns away and tries it again. By such trial & error, Theseus finally gets through the labyrinth and ends the play by touching the “cheese,” an electrical terminal that rings a bell.

On his second trip through the same labyrinth, Theseus shows his talent. This time he never blunders, never touches the walls. He scurries along the corridors, whisks around the turns and gets to the cheese in twelve to 15 seconds. If he starts at a part of the maze that he did not explore on his first trip, he uses his trial & error method until he reaches a familiar part. Then he dashes for the cheese with confident precision.

Theseus in the last analysis isn’t much of a mouse. The explanation for his smart behavior lies in the relays, which move him around by means of a motor-driven magnet. They remember all his successful moves. So when he makes his second trip, the relays whisk him without an error along the correct path.

Dr. Shannon has a good time with Theseus and seems much attached to him, but he did not create the mouse and his labyrinth just for fun. They are useful in studying telephone switching systems, which are very like labyrinths. In effect, each telephone call is a mouse that has to find its way to the cheese (the called telephone) in the shortest possible time.