Brown capuchin monkeys (Sapajus apella) plan their movements on a grasping task.

Motor planning is a relatively complex cognitive skill in which an actor modifies a behavior to anticipate the future consequences of the action. Studying motor planning in nonhuman primates may provide a better understanding of the roots of human planning abilities. In this study we presented capuchin monkeys (Sapajus apella) with a horizontal dowel baited on either the left or right end. A radial grasp on the dowel with the thumb facing toward the baited end would be the most efficient grip selection when bringing the dowel to one's mouth and indicate motor planning. Ten of the 12 monkeys tested spontaneously used a radial grasp significantly more often than expected by chance. Results demonstrate a more ubiquitous expression of motor planning abilities than previously seen in capuchin monkeys. Adaptation of this method of testing may be useful in evaluating motor planning capacity in other primates.