The adaptive value of preference for immediacy: when shortsighted rules have farsighted consequences

Results from the operant laboratory suggest that short-term benefits guide animal feeding decisions. These results appear to contradict evolutionarily-motivated models of foraging that emphasize long-term benefits. Because of this contradiction, some behavioral ecologists argue that natural selection must favor short-term benefits in some unknown way. This study addresses the contradiction by testing the feeding preferences of captive blue jays in two economically equivalent situations. The first situation follows the operant literature's “self-control” paradigm; jays make a binary choice between small-immediate and large-delayed options. The second situation is modeled on patch-use problems; the jays make a leave-stay decision in which “leaving” leads to small amount in a short time, and “staying” leads to larger amount in a longer time. In the self-control situations, the observed outcome agrees with short-term rate maximizing, as other investigators have reported. In the patch situation, the results agree more closely with long-term rate maximizing. The text explains how a rule of preference based on short-term rate comparisons can account for both situations. It is argued that natural selection may have favored short-term rules because they have long-term consequences in many natural foraging situations.