Friday 16 December 2005

The most interesting thing I've seen in weeks.

As ever, it's Language Log with the fascinating stuff:

[Philip Tetlock recounts] an anecdote about an experiment that "pitted the predictive abilities of a classroom of Yale undergraduates against those of a single Norwegian rat". The experiment involves predicting the availability of food in one arm of a T-shaped maze. The rat wins, by learning quickly that is should always head for the arm in which food is more commonly available — betting on the maximum-likelihood outcome — while the undergrads place their bets in more complicated ways, perhaps trying to find patterns in the sequence of trials. They guess correctly on individual trials less often than the rat does, although their overall allocation of guesses matches the relative probability of finding food in the two arms very accurately.

Speaking as someone who used to keep Norwegian rats, this surprises me not at all. They're very clever. Although, as it turns out, it's not their cleverness that's enabling them to beat the humans on this occasion.

As usual, the true explanation is simpler as well as more interesting than the false one. It illustrates a beautifully simple mathematical model of learning and behavior, which accounts for a wide range of experimental and real-world data besides this classroom demonstration. And there's even a connection, I believe, to the cultural evolution of language.


The difference was not their interest in deterministic theories, nor their concern for their reputations. The difference was simply that the students got more information than the rat did.


But why does more information make for worse performance? We're used to seeing evolution develop optimal solutions to such basic problems as choosing where to look for food. So what's gone wrong here?


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