By Sharon Begley
Newsweek
April 23, 2007 issue - Whether it is an eerily human bot in a virtual-reality game, an animal looking at you with soulful eyes or a patient in a vegetative state, the question nags and nags and won't go away: is there a thinking, self-aware, conscious mind in there?
Not one that merely exhibits intelligence, since silicon chips do calculations that leave the human brain in the dust and even discover mathematical proofs. And not one merely capable of empathy or grief or cooperation, which chimps, elephants and species in between all manage.
No, the capacity that distinguishes humans has come down to something Augustine identified 1,600 years ago when he asked what "can be the purport of the injunction, know thyself? I suppose it is that the mind should reflect upon itself."
It's called metacognition—the ability to think about your thoughts, to engage in self-reflection, to introspect. It was long thought to be not just something that we have more of or do better than machines or animals, but that we have and they lack.
To know what you know is not only the mark of a skilled game-show contestant who is quick (but not too quick) on the buzzer, but also of consciousness, the last stand for human exceptionalism.
Now, however, this claim is on the rocks as both animals and machines show signs that they can engage in self-reflection.
In the latest study, scientists tested for introspection in rats. Jonathon Crystal and Allison Foote of the University of Georgia trained rats to push one lever when they heard a short burst of static, and a second lever when they heard a long burst. The reward for a right answer was six food pellets.
A wrong answer yielded nothing. But refusing to answer—like a student fleeing an exam room upon seeing the impossible questions—earned the rat a consolation prize of three morsels.
Clearly, the smart strategy was to respond if sure of the answer, but pass if not.
The rats got almost perfect scores when they had to identify two-second or eight-second bursts. But when they heard static of intermediate duration and had to choose "long" or "short," they were twice as likely to decline the test and take the three pellets; they knew what they didn't know.
To make sure the rats were truly introspecting, the scientists then eliminated the opt-out choice and required the rats to choose "long" or "short" for the medium bursts.
The animals got half right, no better than guessing, which suggests that when they opted out it was indeed because they had assessed the contents of their mind—do I know this?—and made the rational choice, the scientists report in Current Biology.
"Rats can reflect on their internal mental states," says Crystal. "They know when they don't know." Other scientists have gotten similar results with dolphins and rhesus monkeys, who also decline to take a test when they don't know the answer. They think about thinking.
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