The effects of stimulus movement on discrimination learning by rhesus monkeys

Abstract

Two experiments were conducted with test-sophisticated adult rhesus monkeys to determine effects of differentiating and nondifferentiating movement cues on two-choice discrimination learning. In Experiment 1, 12 monkeys were given initial learning problems followed by intradimensional shift problems with movement- and color-differentiated stimulus cues. Results indicated that original learning progressed most rapidly with movement cues, but that subsequent task-shift performance was comparable for movement- and color-cue problems. There was no evidence that learning with either cue dimension transferred to subsequent problems involving the other cue dimension. In Experiment 2, 14 monkeys were given a series of two-choice discrimination problems in which discriminanda differed in color only. Problems were presented under two conditions: (1) both discriminanda moved synchronously during the choice period or (2) both discriminanda remained stationary. Results indicated that the monkeys learned more rapidly when discriminanda were moving rather than stationary. It was concluded that motion is a dimension of comparable saliency to color, although the psychophysical properties need further clarification. It was hypothesized that stimulus movement enhances discrimination learning through facilitation of the appropriate allocation of attention.