Effects of shifts in magnitude and delay of reward upon runway performance in the rat

Abstract

Six independent groups of rats were first trained in a runway to receive either 1 or 12 pellets after a delay of 0, 15, or 30 sec (Phase 1). Subsequently (Phase 2), all Ss received 12 pellets under the same delay interval as in Phase 1. Finally (Phase 3), all Ss were delayed 15 sec before receiving the 12-pellet reward. In Phase 1 performance was a positive function of amount of reward and a negative function of delay of reward. The effects of magnitude and delay of reward were independent of each other. In Phase 2 no elation effects were obtained in the 0-, 15-, or 30-sec delay conditions. A depression, but not an elation, effect was obtained in Phase 3.