Taste aversion learning induced by forced swimming in rats.

Two experiments demonstrated that forced swimming endowed rats with aversion to the taste solution consumed before the swimming. In Experiment 1, the rats given a trial of taste-swimming sequence drank less of the taste solution in a later test than did the rats given a taste-alone trial. The rats given a trial of taste-poisoning-swimming sequence, however, drank more of the taste solution in the testing than did the rats given a trial of taste-poisoning sequence. These results suggest that some effects of swimming (e.g., energy expenditure caused by physical exercise) induce conditioned taste aversion although they attenuate taste aversion conditioned by poisoning. The attenuation of poison-induced taste aversion by swimming has been reported in the literature, but the swimming-induced taste aversion is novel. Experiment 2, accordingly, was planned to confirm this phenomenon with a differential conditioning procedure, where one of two taste solutions was paired with swimming while the other was not. After a few repetitions of these two types of trials, the rats' intakes of these two solutions were differentiated to show that swimming has the ability to cause taste aversion.