Abstract
When choosing between two alternatives that deliver the same amount of food per trial in the long run, organisms are calledrisk-averse if they choose a small certain reinforcer over a larger probabilistic reinforcer. They are calledrisk-prone if they choose the larger probabilistic reinforcer. This experiment attempted to predict whether rats would be risk-prone or risk-averse on the basis of their separate choices between reinforcers differing in probability and reinforcers differing in amount. Choice was measured with an adjusting-delay procedure, which provided estimates of indifference points, or pairs of alternatives that a subject chose about equally often. The subjects were usually more responsive to differences in amount than to differences in probability, leading to predictions of risk-proneness for choices between two probability-amount combinations. The predictions were confirmed in almost every case. As the number of food pellets delivered by the two alternatives was increased while maintaining a 2:1 difference between them, the tendency toward risk-proneness declined. These results suggest an explanation of the inconsistent findings obtained in previous experiments on risk-taking by rats.
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This research was supported by Grant MH 38357 from the National Institute of Mental Health.
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Mazur, J.E. Choice between small certain and large uncertain reinforcers. Animal Learning & Behavior 16, 199–205 (1988). https://doi.org/10.3758/BF03209066
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DOI: https://doi.org/10.3758/BF03209066