Residual Fear of the CS as a Function of Response Prevention After Avoidance or Classical-Defensive Conditioning in the Rat

The problems of assessing fear reduction after response prevention techniques were reviewed. After surveying the literature it was apparent that whether or not response prevention actually reduced a subject\u27s fear to the CS was still an unanswered question. The present investigation attempted to measure fear to the CS after response prevention by employing a conditioned emotional response paradigm. The first major hypothesis was that fear of an auditory CS (conditioned in an avoidance paradigm) is reduced during response prevention. Another hypothesis considered the possibility that conditioning may occur to aspects of the conditioning environment seas well as to the specific CS. The study was also interested in evaluating the effectiveness of response prevention when fear had been learned under two different conditions. One condition, avoidance conditioning, provided the animal with the opportunity to learn to actively avoid the shock UCS. The second condition, classical defensive conditioning, did not offer the animal the opportunity to avoid the UCS. Seven groups of 10 female rats were run in the experiment. Three groups were avoidance-trained to a criterion of 10 successive avoidances. One of these groups (Condition A-B) was blocked in the shuttle box where all fear conditioning occurred. Blocking consisted of presenting a white noise CS f or 15, 2O-sec. periods with a variable 1 min. inter-stimulus interval. One group was nonblocked in the animals\u27 home cage (Condition A-NBHC). The third group was nonblocked in the shuttle box (Condition A-NBSB). Two other groups were trained in a Classical-Defensive paradigm. Animals in these groups were matched to animals in Condition A-Bin terms of number, order and duration of CSs and UCSs. One of these classical defensive groups was blocked (Condition CD-B). The other group was nonblocked in its home cage (Condition CD-NBHC). The remaining two groups served as control groups. A backward control group (Condition BC-NBHC) was matched to Condition A-NBHC in terms of number, order and duration of CSs and UCSs. A sensitization control group (Condition SC-NBHC) was matched to Condition A-NBHC in terms of number, order and duration of CS presentations. Each of the control conditions was nonblocked in its home cage. The results indicated that Condition A-B showed significantly less response suppression than Condition ANBHC. This suggested that response prevention was an effective technique in reducing the subjects\u27 fear to a CS. Another finding was that Condition A-B did not differ from Condition A-NBSB. This suggested that conditioning of fear did occur to the conditioning environment and that this conditioned fear was subsequently blocked in Condition A-NB SB. Condition A-B showed significantly more response suppression than Condition CD-B. This suggested that the response prevention technique was more effective when fear to the CS was learned in a classical as compared to an avoidance paradigm. Theoretical implications and generalizations to Implosive Therapy were discussed