Active role of the shock-avoidance contingency in shuttlebox-avoidance learning in Fischer344 rats

Different groups of Fischer344 rats acquired and maintained shuttlebox-avoidance responses under one, two, all three, or none of the shock-avoidance, warning-signal (WS) termination, and shock-escape contingencies. The intertrial interval was fixed at either 30 or 60 s. Removal of the shock-avoidance contingency led to a marked disruption of avoidance behavior at both intervals. This result was not produced by a selective punishment effect of the avoidance response by an inevitable shock. Thus, the shock-avoidance contigency provided particularly effective control over the avoidance learning. The WS termination contingency appeared to have little overall effect at the 60-s intertrial interval. It is suggested that response-contingent stimulus change served only as a discriminative cue for the absence of a shock.