Some effects of response-independent shocks after unsignaled avoidance conditioning in rats

Abstract

After extended unsignaled avoidance training, the majority of rats continued frequent responding during long periods when only response-independent shocks were presented. Most responses were shock elicited, i.e., followed immediately after shock. Response rates were directly related to both the frequency and the intensity of response-independent shocks. Responding continued to approximately the same extent, whether shocks were presented at fixed or variable intervals. Few responses were directed toward a second lever in the test chamber, even when the lever previously associated with avoidance was removed. When avoidance was scheduled on the second lever, the rats learned to avoid by operating it. Meanwhile, responding on the first lever became infrequent. Subsequently, when only response-independent shocks were presented, almost all responses occurred upon the lever initially associated with avoidance. Responding that was elicited by response-independent shocks was suppressed by response-dependent (punishment)_shocks of the same intensity. When punishment was withdrawn, recovery of responding occurred. An explanation of the results based upon shock-elicited behaviors is preferred to one stressing unextinguished avoidance responding.