After preliminary training on a jumping stand rats were presented with an insoluble problem with brightness cues present, and finally given a soluble brightness discrimination problem. In different experiments reserpine was administered (a) during all 3 phases, (b) during the insoluble-problem period, or (c) after fixations were demonstrated on the soluble problem. Reserpine did not interfere with motor functions or brightness discrimination, nor did it prevent or reverse fixations. It is suggested "that the behavioral effects of reserpine consist of the attenuation of fear associated with negative incentives." From Psyc Abstracts 36:02:2DK83F. (PsycINFO Database Record (c) 2006 APA, all rights reserved)