Interactive effects of reward magnitude and intertrial intervals on resistance to extinction

Resistance to extinction was examined as a function of the interactive effects of reward magnitude and intertrial intervals (ITIs). Running times in a straight-alley runway were obtained from 64 rats during acquisition and extinction. During acquisition, two magnitudes of reward were factorially combined with two durations of ITI. The reward was delivered on a continuous reinforcement schedule. During extinction, one-half of each acquisition treatment group was transferred to the alternate ITI duration. In acquisition, the large reward treatment led to faster running. This was a result of slower running in the small reward - short ITI group; the small reward - long ITI group ran as fast as the large reward groups. In extinction, reward magnitude effects on resistance to extinction were a function of the acquisition ITI. When the acquisition ITI was long, small reward produced more resistance to extinction than large- when the acquisition ITI was short, no difference was produced. Reconciliation of previous research findings was attempted on the basis of this finding.