EXTINCTION AND RECONDITIONING OF CLASSICALLY-CONDITIONED FEAR BEFORE AND AFTER INSTRUMENTAL LEARNING - EFFECTS OF DEPTH OF FEAR EXTINCTION

In four experiments, fear was classically conditioned to the situational cues in one side of a two-compartment apparatus. The number of hours of extinction of fear (exposure to the cues in the conditioning compartment) was varied across experiments from 1 to 30. Fear was then reconditioned in some groups. Treatment effects were evaluated by the performance, in the absence of shock, of a hurdle-jumping response that allowed escape from the fear-eliciting stimuli in the conditioning compartment to an adjacent safe compartment. This instrumental learning took place before and/or after the extinction treatment. It was found that during the treatment that resulted in the extinction of fear there was no concomitant extinction of the instrumental response previously learned on the basis of fear. Also, after extinction, the performance of the already learned hurdle-jumping response provided a more sensitive index of fear than did the new learning of this response. The occurrence of hurdle jumping depended upon the presence of associative strength both of fear and of the instrumental response, a finding supporting two-factor fear theory. Some fear remained even after 30 h of extinction. The data are consistent with the proposition that reconditioning occurs more rapidly than original conditioning. (C) 1994 Academic Press, Inc.