Conditioned inhibition of fear resulting from negative CS-US contingencies.

Abstract

Two experiments are reported which indicate that negative contingencies between CSs and shock set up conditioned inhibitors. In Experiment 1, this inhibition was measured by retardation in the subsequent acquisition of a CER to the CS. Stimuli with greater negative CS-US contingencies were more retarded in CER acquisition; various control procedures were employed. In Experiment 2, inhibition was measured by a summation technique. Conditioned stimuli with a history of greater negative relations to shock were more disruptive of the CER normally elicited by a second CS. Taken together, the experiments support the general hypothesis that CS-US contingency is an important factor in fear conditioning. American studies of Pavlovian conditioning have concerned themselves primarily with excitatory conditioning; very little exploration has been made of the phenomena of inhibitory conditioning. Although we know a great deal about procedures for setting up a CS an an elicitor of a Pavlovian conditioned response, our knowledge of the parameters affecting the establishment of a stimulus as a condi