Rhesus macaques (Macaca mulatta) spontaneously generalize to novel quantities in a reverse-reward contingency task

Abstracting generalities from concrete experience allows the application of acquired knowledge to novel situations, a hallmark of primate cognition. Abstraction may also enable some animals to overcome prepotent biases, by allowing them to treat prepotent stimuli and responses more flexibly. The aim of the current study was to determine whether rhesus macaques (Macaca mulatta) could generalize successful performance on an executive control task with one training exemplar to novel exemplars. Three monkeys learned a reverse-reward task in which they chose between one and four food items. They had to select the smaller quantity to receive the larger one, and so had to inhibit the prepotent selection of the larger quantity. After they learned the task, a transfer test assessed whether they had learned only about the quantities experienced or whether they could generalize to novel quantities. All three rhesus monkeys spontaneously generalized to novel quantities, showing that this species has the ability to generalize significantly beyond the immediate perceptual experience and use this ability to control lower-level, prepotent responses.