"What you see may not be what you get": Reverse contingency and perceived loss aversion in pigeons.

The reverse-contingency task is a task in which one is given a choice between two rewards, but one receives the larger amount only if one chooses the smaller amount. This task is very difficult for chimpanzees unless the choice is between symbolic representations of the amounts. We found that pigeons can learn this task easily, if the reward amounts are associated with distinctive colors and the choice is delayed by 5 s. The reverse-contingency task involves three components: a loss when choosing one alternative, a gain when choosing the other, and the contrast between what was expected and what occurred. In Experiment 2 we separated the loss from the gain and found that experiencing a loss is sufficient for pigeons to learn to avoid that alternative. Finally, we found evidence for perceived loss aversion. When pigeons were offered a small amount of food and they received that amount, they preferred it over an alternative that offered them a larger amount but gave them only the smaller amount (a perceived loss). The results indicate that loss aversion, based on reference dependence, is likely a general phenomenon, and not only found in humans and other primates. We suggest that it can be attributed to contrast, the difference between what is expected and what is obtained, and it is related to the endowment effect and the mere ownership effect found in humans.