Pigeons feel the urge to gamble
Published 13/10/2010 | 09:09
Pigeons feel the urge to gamble just like humans, scientists have learned.
Birds given the chance to play a pigeon "fruit machine" could not resist the lure of the jackpot - even when the odds were stacked against them.
They appeared to be psychologically hooked in much the same way as humans who buy lottery tickets and visit casinos.
Researchers set up an apparatus to test pigeon gambling tendencies with similarities to human slot machines. The birds were trained to peck on either of two keys that displayed projected vertical or horizontal lines as well as red, yellow, green and blue colours. Pecking keys produced rewards of food pellets, which varied according to the displays.
The "jackpot" prize of 10 pellets was only delivered after a key was pressed that presented a vertical line and a certain "signal" colour, for instance red. Vertical lines associated with another colour produced zero pellets. By pecking a vertical line key, pigeons had a 20% chance of winning 10 pellets but an 80% chance of receiving none.
If a bird pecked a key with a horizontal line, it was guaranteed three pellets whatever colours were presented.
Six of the eight pigeons taking part in the experiment showed a strong desire to keep pecking the vertical line key in the hope of winning the jackpot, the scientists found. This was despite the fact that over a series of repeated trials they could have obtained 50% more pellets by choosing the alternative option.
Such "maladaptive" decision making is typical of human gamblers, said the researchers writing in the journal Proceedings of the Royal Society B.
The pigeons challenged the view that non-human animals should avoid "a poor gamble" because it might affect their survival.
Psychologist Professor Thomas Zentall and Jessica Stagner, from the University of Kentucky in Lexington, wrote: "The results of these experiments suggest that pigeons show a tendency to make maladaptive decisions similar to those of humans. That is, pigeons prefer a signal for a low probability, high payoff alternative over a signal for a certain low payoff alternative that on average provides 50% more reinforcement."