Visual discrimination learning of random figure problems by rhesus monkeys

In a two-choice discrimination learning paradigm, a U-shaped function was found between trials to criterion and the number of sides comprising the random figure discriminanda. These data are consistent with results from human Ss and suggest similar information processing capabilities in the two species. Changing the orientation of the stimulus figures after the discrimination had been learned only partially disrupted subsequent discrimination performance. Any single difference in selected form attributes between the two figures comprising a problem was not a good predictor of learning speed, suggesting that monkeys use a combination of such factors.