International Journal of Comparative Psychology

We evaluated the effects of varying temporal and spatial parameters on behavioral transitions within a water seeking situation. Subjects were 8 experimentally-naïve, male Wistar rats divided in two groups of 4 rats. For both groups, two independent schedules of water delivery were simultaneously available in two different locations of the experimental chamber. For Group 1, water was delivered with a constant periodicity. For Group 2 water was delivered randomly in time but keeping constant the average length of time between deliveries. Water deliveries were independent of rat’s behavior. In successive phases of the study, the frequency of water delivered in one location increased while the frequency of water delivered in the second location decreased, keeping constant the total number of water deliveries. Rats under the constant periodicity spent more time in the location where water was initially provided. For rats under the random periodicity, time spent on each location varied according to the proportion of water delivered on each site. Results are discussed in terms of the discrepancies with optimization models, emphasizing that, apparently simple behaviors, in a relatively simple environment, cannot be understood in terms of a single, overall encompassing concept, such as adaptation.