No abstract

Experiment 1 investigated the proposition that rats cover the source of aversive stimulation with the bedding material available to them and sought to determine whether familiarization with this material would affect burying. The results indicated that rats are no more likely to cover an aversive object than they are not to cover it, although they collect a considerable amount of bedding material in the area surrounding the aversive object. Experiment 2 demonstrated that the rat's defensive "burying" toward an aversive object is affected by the subject's predisposition to displace material toward the front side of the apparatus. Some theoretical complexities involved in considering the act of "burying" toward an aversive object as a defensive behavior are discussed.

Two experiments were conducted with rats to investigate variables responsible for the effectiveness of using a safe platform in two-way avoidance training and to evaluate the relative efficacy of several theoretical positions (conflict reduction, reinforcement, and freezing attenuation) that were offered to explain the wide differences in performance between platformed and conventional two-way signaled avoidance learning. The variables presumed to be critical by each theoretical position were experimentally manipulated by presentation or withdrawal of a "safe" platform located over the grid floors at various time intervals and for different durations during avoidance trials. The results failed to provide unequivocal support for the conflict-reduction hypothesis but provided strong support for the reinforcement hypothesis. No conclusive evidence concerning the freezing-attenuation hypothesis was obtained, although several findings were relevant to it.