Gambling Behavior: An Animal Model

When humans engage in commercial gambling, they are making suboptimal choices because the return is typically less than the investment. Pigeons and rats too show suboptimal choice, for example, when pigeons choose between one alternative that 20% of the time provides them with a signal for 100% reinforcement and a second alternative that provides them with a signal for 50% reinforcement. The pigeons' strong preference for the suboptimal choice is controlled primarily by the value of the signal that predicts reinforcement (a win), rather than how often it occurs (the probability of a win or a loss). A second mechanism, positive contrast between reinforcement expected and obtained, also appears to play a role. Suboptimal choice appears to be related to impulsivity and is correlated with the degree to which reinforcers are discounted by delays. Motivation also plays a role as pigeons on a more restricted diet choose more suboptimally than pigeons on a less restricted diet. In addition, pigeons that spent some time in an enriched environment choose less suboptimally than unenriched pigeons. Research conducted with this animal model of gambling may have implications for the treatment of problem gambling behavior by humans.