Consummatory successive positive contrast with aversive solutions in infant rats: Replication and generalization to a higher concentration of a bitter solution.

Successive positive incentive contrast is typically demonstrated when a group of subjects shows a higher consumption of a reinforcer than a control group, if they were previously exposed to a similar one of lower magnitude. Recently, a similar effect was observed by lowering the concentration of a quinine solution in the experimental group. On the other hand, the presence of a familiar odor has been shown to attenuate responses elicited by aversive stimuli in infant rats. This experiment was designed to assess if the presence of a familiar odor decreases the responses elicited by an aversive solution. Two groups of rats were exposed to a consummatory positive successive contrast procedure, decreasing the concentration of a quinine solution (i.e., 0.2-0.01 %). Half of the subjects in each group was tested in the presence of the homecage odor during the postshift phase. A positive successive contrast effect was evidenced by subjects in the experimental group, consuming more of the lower-concentration solution during the postshift phase. The presence of the odor, however, exerted no effect. Results are discussed in the context of the social buffering and positive successive contrast effects.