Paradise Lost

When Dr. William Grey Walter of Bristol, England created his first mechanical turtles, Elmer and Elsie (TIME, March 27, 1950), he made them happy beasties. With their photoelectric eyes they could seek out the dim light that was suitable to bask in as well as the bright light that led them to their food, i.e., electric current to recharge their batteries. When they bumped into obstacles, they knew how to back away on their electrically driven wheels and try a different angle.

This was quite enough intelligence for a simple, happy life. Elmer and Elsie might starve to death if their batteries ran down far from a current supply, but they did not dread death or any other misfortune. Their two-tube brains had no memories to plague them with apprehension. So they crept in innocent bliss around the Walter house, alternately resting and sipping electricity like a mechanical Adam & Eve in a pre-reptilian Garden.

Cruel Memory. But Dr. Walter, who is one of Britain's leading neurophysiologists, had a stern duty. He was building his pets for a purpose: to study by electronic analogy the basic workings of the human brain. Since the brain has memory and the ability to learn, he felt that his pets should be given similar qualities, though he knew it might destroy the simplicity of their lives.

In the current Scientific American, Dr. Walter describes his new, more sophisticated pets. One type is designed, as before, so that when it sees a light, it scurries toward it in search of electric food. In addition, it can also hear a whistle, but at first it does not react to the sound. The whistle, however, is "remembered" in the form of long-lasting oscillations in the new eight-tube brain. When the creature hears a whistle just before it sees a light, the two stimuli are blended and remembered together. After this has happened enough times, these combined memory oscillations acquire a compelling power. When the whistle blows again, they force the mechanical turtle to react (scamper forward) just as if it had seen a food-promising light.

Conditioned Frustration. This is closely analogous to a "conditioned reflex," one of the brain's mechanisms for learning. By changing the circuits slightly, Dr. Walter can condition the new Elsie and Elmer to stop and back up when he whistles. They do so because they have learned to associate the whistle with the touch-signal they feel when they hit an obstacle.

Such "training" is not permanent, any more than it is with humans. After a while the memory oscillations die away; the sound of the whistle becomes ineffective again, its learned meaning forgotten. But while the memory lingers, the mechanical turtle is not a simple, well-adjusted beast. It flees from a harmless whistle, or rushes forward eagerly for food that is not there. And this is not the worst. Dr. Walter has figured out a brain with built-in makings of madness. So fitted, his creatures have two "learning circuits" instead of one; they can be trained to react in two different ways to the same stimulus. A whistle, for instance, can come to mean both food (go forward) and an obstacle (draw back). So, when they hear a whistle, the turtles cower in helpless indecision, like certain human neurotics whose emotional circuits are tangled.

Dr. Walter can cure his pets of their neuroses; all he has to do is disconnect a few circuits. But if he is ever called before an electronic St. Peter, he will have much to answer for. He created a race of happy (though simple) machines; then drove them to distraction by giving them too much brain.

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