Effects of Prospective Monetary Rewards on Movement Initiation in Choice Reaction-Time Tasks with Varying Stimulus-Response Compatibility

Abstract

Although numerous studies have examined the facilitative and deleterious effects of monetary rewards on human behavior, little research (if any) has examined the connection between monetary rewards and choice reaction time (CRT) under varying stimulus-response (S-R) compatibility conditions. Twenty self-declared right-handed, undergraduate students, with an equal number of males and females in each group (M age = 21.6 yr., SD = 2.13), were randomly assigned to one of two groups: monetary rewards or control. Participants in the monetary rewards group had a chance to draw for a cash prize of $30.00 if their CRT performances (both speed and accuracy) were at the 50th percentile or better. Participants completed 4 tests of 40 trials that had varying S-R compatibility. Two subscales of the modified Brunel Modified Scale (BRUMS) were administered prior to testing and immediately after a 40-trial test. Dependent variables included CRT, error scores, and BRUMS survey data. Mixed-design analyses of variance (ANOVAs) indicated that monetary rewards did not affect movement initiation, response accuracy, or tension and confusion levels. However, strong S-R effects were found, based on CRT, error scores, and BRUMS data. These results are discussed with respect to the mechanisms of monetary rewards and S-R effects.