INFLUENCE OF ORDER OF OCCURRENCE OF NON-REWARD AND LARGE AND SMALL REWARD ON ACQUISITION AND EXTINCTION

The 2 * 2 factorial design employed 48 rats in the runway. Manipulated were number of nonrewarded (N) trials preceding the rewarded trial (N-length, 3 vs. 1) and order of occurrence of the larger reward magnitude (.09 vs .675 gm.), either before or after nonreward. The intertrial interval was 15 min. Consistent with previous results under short intertrial intervals (ITIs) (e.g., 30 sec.), but inconsistent with a previous finding under 15-min. ITIs, resistance to extinction increased as N-length increased. Also found was that resistance to extinction was greater when large reward followed, rather than preceded, nonreward. The results were examined relative to several current hypotheses of the effects of partial reward at different ITIs. (15 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.