A PRELIMINARY RESOLUTION OF THE RETENTION OF DISTRIBUTED VS MASSED RESPONSE PREVENTION IN RATS

This study consisted of two experiments conducted to investigate the d ifference in efficacy and retention of distributed response prevention when compared to massed response prevention using an animal model of avoidance learning. The purpose was to obtain an estimate of the over- all treatment time for response prevention that begins to be affected by the treatment, either distributed or massed. In Exp. 1, 50 rats wer e given two trials of escape learning in a one-way black-white shuttle -box. Groups received response-prevention treatment or nontreatment in 9 1-min. distributed sessions or 1 9-min. massed session. Subjects we re tested using a passive-avoidance paradigm immediately following tre atment, 24 hours, and 720 hours (30 days) later. Analysis showed that with an over-all response-prevention time of 9 min., response-preventi on treatment was effective in reducing avoidance behavior, that the ef fect was retained, and that there were no differences between distribu ted and massed groups. These results led to Exp. II in which 50 rats w ere exposed to the same training procedure as in Exp. I. These groups received response-prevention treatment or nontreatment in 12 15-sec. d istributed sessions or one 3-min. massed session. Analysis of passive- avoidance testing immediately following treatment, 24 hr., and 720 hr. later showed that, when the over-all response-prevention time was 3 m in., only groups with distributed treatment showed reduction of avoida nce behavior and retention of the treatment effects. Since past studie s have produced inconsistent findings in comparing distributed vs mass ed delivery of response-prevention treatment these two experiments are intended to serve as a preliminary resolution of the past differing r esults. When the over-all treatment time is longer than 3 min., there is no delivery of treatment effect. However, with 3 min. of over-all t reatment time, distributed delivery was necessary to facilitate the tr eatment effects. Implications for animals and humans are discussed.