Effects of within-session incentive contrast on instrumental acquisition and performance.

Abstract

Three groups of 10 rats were magazine trained and bar press trained daily for 28 days. Ten min. of 1-min. fixed interval magazine presentations were followed by 10 min. of 1-min. fixed interval bar pressing. The group whose incentive was shifted up from magazine to bar press (4-11.3% sucrose) showed an initial depression of acquisition bar press rate but an eventual asymptotic facilitation, compared with the 11.3/11.3% controls. The group whose incentive was shifted down (32/11.3%) showed an initial (but unreliable) facilitation and an asymptotic depression. Interpretation of these results is suggested in terms of the development of discrimination between magazine and bar press incentives.