A human analogue of discrimination contrast: S− contrast as a function of magnitude of S+

Abstract

In the present study, two groups of human Ss received differential reward conditioning for accurately tracing red or blue star patterns. A control group received only small reward in both discriminanda. The present study replicated the findings of previous animal and human studies in that a significant negative S− contrast effect was found. In addition, it was shown that this effect increased as a function of the magnitude of reward in the S+ discriminandum. The latter finding has been obtained previously with infrahuman Ss but evidently not with human Ss; hence, the generality of negative discriminative contrast effects have been extended significantly.