The Effects of Extended Blocking, Motivation, Chain Flooding, and Safety Testing on Approach Measured Fear Reduction Following Response Prevention in Rats

Sixty male Wistar rats were trained to avoid a CS grid with 0.7mA(UCS) shock under food deprived and non-deprived conditions. There was no difference in deprived and non-deprived conditions in fear reduction as measured by subsequent approaches to the CS following response prevention. Response prevention varied over 3 treatments consisting of O response prevention for 20 subjects, response prevention until exploratory behavior occurred for 10 cumulative seconds for 20 other subjects, and response prevention until exploratory behavior occurred for 120 cumulative seconds for 20 other subjects. No differences were found between these treatments in approach measures to the CS during a 10-min. fear test. An additional 5-hr. fear test conducted on 20 subjects revealed no differences in fear as a result of response prevention. Later exposing the subjects to the entire chain of events leading to their avoidance of the CS resulted in fear reduction. A comparison between dependent approach measures to a CS and dependent avoidance measures from a CS indicated that subjects that would not approach a CS following response prevention would not avoid the CS. The availability of safety testing, defined as a graded exposure to the CS during fear testing following response prevention led to increased approaches to the CS as compared to discrete or non-continuous CS exposure. The discussion suggested that response prevention was effective in reducing fear only when the entire chain leading to the learning of the avoidance response was exposed to the subject during response prevention. The notion of individual differences in reaction to response prevention was challenged. The superiority of dependent approach measures to the CS over the traditional dependent avoidance measures was discussed. Graded exposure to the CS during fear testing was found to lead to more approaches to the CS than discrete or non-continuous exposure to the CS