Magnitude of partial reward, irregular reward schedules, and a 24-hour ITI: A test of several hypotheses

Gave 4 groups of male Holtzman rats (N = 36) 22 acquisition trials under different magnitudes of partial reward. Resistance to extinction was found to be an increasing function of a sequential variable, magnitude of reward occurring on rewarded trials following nonrewarded trials. Neither total magnitude of reward nor the discrepancy between anticipated reward and reward received on nonrewarded trials effected resistance to extinction. These results, which are consistent with the sequential hypothesis, seem inconsistent with both the dissonance hypothesis and the frustration hypothesis. Implications for various recent interpretations of the effects of ITI and regularity of reward schedules on resistance to extinction is indicated. (18 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved).