What do pigeons have in common with problem gamblers?

Expecting a cash bonanza from buying lottery tickets or playing slot machines in a casino might brand someone a dupe or pigeon. That comparison, in fact, is much more accurate than meets the eye. In a new study, University of Kentucky psychologists found that pigeons and problem gamblers seem to have a particular trait in common — impulsive behavior. The findings are important because they suggest that training in impulse control could help people with gambling problems.

The researchers' previous work showed that pigeons do gamble. In experiments that trained pigeons to choose to peck keys for food pellets, the birds placed high-stakes bets. They consistently pecked a key that would give them a big jackpot — 10 pieces of food — but only paid out 20 percent of the time, rather than a key with a more modest payoff of three food pellets 100 percent of the time. So, the jackpot would give them an average of two food pellets per trial, whereas the optimal alternative would give them three food pellets per trial.

The findings piqued the researchers' curiosity. Could the pigeons' tendency to risk no payoff most of the time for the rare possibility of winning a big jackpot be related to impulsivity? To find out, they added another procedure to their experiments.

A time-honored test for impulsivity looks at the ability to delay gratification. If a gambler, or a pigeon, could have a small reward now or a heftier payoff later, which would either of them choose? The less time they're willing to wait for the large prize, the more impulsive they are.

So, lead author Jennifer Laude, a doctoral psychology student, and her colleagues tested the pigeons for their impulsivity as indexed by the delayed reward task. They found that the more impulsive birds — those that were more partial to pecking keys that gave them a little food immediately instead of a larger number of pellets for which they'd have to wait up to 20 seconds — were more likely to choose the gambling-like alternative associated with the jackpot than the sure thing.

The results suggest that the pigeons gave more weight to winning the jackpot and less weight to losing than optimally they should have, says Thomas Zentall, PhD, a co-author of the study and senior researcher in the psychology department's Comparative Cognition Laboratory. That is, the birds weren't wary enough about pecking keys that usually didn't provide food, he says.

It's the same phenomenon seen in pathological or problem gambling, which is clinically recognized as an impulse control disorder. "Not surprisingly, pathological gamblers are relatively unaffected by their losses and attend almost exclusively to their seldom occurring gains," says Zentall.

The study results suggest that impulsivity may make a person prone to having gambling problems. Thus, the results have clinical implications. "The findings suggest that training in impulse control might help reduce problem gambling behavior," says Zentall.

Online publication in the Journal of Experimental Psychology: Animal Behavior Processes is expected in early June. Incoming editor Ralph Miller, PhD, of the psychology department at the State University of New York at Binghamton, says the study again demonstrates that "animal models can be useful not only in developing treatments for human physical illnesses, but also for mental/behavioral pathologies."

—Rebecca Voelker