Decision making under risk: framing effects in pigeon risk preferences.

When humans face probabilistic outcomes, their choices often depend on whether the choice is framed in terms of losses or gains. In the present research, we gave pigeons a choice between risky (variable) outcomes and safe (constant) outcomes that resulted in the same net reward. In Experiment 1, in which the outcomes represented a loss, the pigeons preferred the risky alternative. In Experiment 2, in which the outcomes represented a gain, the pigeons were indifferent between the two alternatives. In Experiment 3, in which the outcomes represented neither a gain nor a loss, the pigeons strongly preferred the risky alternative. The results were interpreted in terms of the relative value of gains and losses given to the alternatives by pigeons in the context of a risky and safe choice. In Experiment 4 we tested that hypothesis by giving pigeons a choice between a risky and safe alternative with the same net outcome, in the context of a gain associated with the safe alternative, but no gain or loss associated with the risky alternative. In support of the interpretation of the first three experiments, with the safe alternative associated with a gain, the pigeons now preferred the safe alternative. These results were discussed in terms of economic and foraging theories and were contrasted with the aversion to uncertainty (risk) more typically shown by humans.