To shed light on why humans often fall short of the best strategy with this kind of problem, scientists investigated pigeons, which often perform quite impressively on tasks requiring them to estimate relative probabilities, in some cases eclipsing human performance. Other animals do not always share the same biases as people, and therefore might help provide explanations for our behavior.
Scientists tested six pigeons with an apparatus with three keys. The keys lit up white to show a prize was available. After the birds pecked a key, one of the keys the bird did not choose deactivated, showing it was a wrong choice, and the other two lit up green. The pigeons were rewarded with bird feed if they made the right choice.
In the experiments, the birds quickly reached the best strategy for the Monty Hall problem – going from switching roughly 36 percent of the time on day one to some 96 percent of the time on day 30.
On the other hand, 12 undergraduate student volunteers failed to adopt the best strategy with a similar apparatus, even after 200 trials of practice each.
It is a pity I did not have this paper in time for the big book. It would have been perfect!
The 12 undergraduates described here seem to have performed exceptionally badly. Other such experiments have shown higher rates of people learning the correct solution after repeated trials, as I describe in Chapter Six of the book. Still, ninety-six percent is pretty impressive.
The technical paper, published in The Journal of Comparative Psychology, has been printed out and is now sitting on my desk. Now to find time to read it!