RESPONSE OF THIRSTY RATS TO ABSENCE OF WATER - FRUSTRATION, DISINHIBITION OR COMPENSATION

Water-deprived rats were allowed to drink in an experimental chamber during a series of training trials and were then presented with an empty water sprout during a single test trial. Their initial response to absence of water was to bite, sniff and paw at the empty spout (spout-directed behavior), after which they engaged in activities such as eating, grooming and exploration of the chamber. By comparison with control animals that had no expectation of water, experimental rats performed these latter activities in a bizarre ''speeded-up'' manner, which was quantifiable as an increase in local rate. Both the occurrence of spout-directed behavior and the increase in local rate of other activities were enhanced by increasing the prior level of water deprivation and by offering a more palatable fluid during training. The results were related to current models of behavioral switching.