Abstract

The present study examined whether conditioned fear to a CS would decrease after extensive active avoidance training. Suppression ratios calculated from the change of general activity induced by CS presentation in an activity box were used as a measure of conditioned fear. In experiment 1, rats received classical conditioning by pairing a light CS with footshock US 1, 3, 9, or 27 times and were tested for conditioned fear. The more conditioning trials the animals received, the higher the conditioned fear to the CS. In experiment 2, animals received 15 active avoidance training trials on day 1 and assigned to 3 groups based on their performance. On day 2, they were trained to a criterion of 3, 9, or 27 consecutive avoidance responses, and one day later, tested for conditioned fear to the CS. All three groups showed similar degree of conditioned fear. This result indicating that extensive active avoidance training does not decrease conditioned fear to the CS is not consistent with the results of most of the previous studies, and possible reasons for this discrepancy is discussed.