Capuchin monkeys, Cebus apella, were tested in five studies in which two individuals competed over food. When given a choice between retrieving a piece of food that was visible or hidden from the dominant, subordinate animals preferred to retrieve hidden food. This preference is consistent with either the hypotheses that 1) the subordinate knew what the dominant could and could not see or 2) the subordinate was monitoring the behavior of the dominant and avoiding the piece of food that it approached. To test between these alternatives subordinates were released with a slight head start forcing them to make their choice (between a piece of food hidden or visible to the dominant) before the dominant entered the area. Unlike chimpanzees, subordinates that were given a head start did not preferentially approach hidden pieces of food first. Therefore, the current experiments provide little support that capuchin monkeys are sensitive to what another individual does or does not see. Results are compared with those obtained with chimpanzees in the same paradigm and the evolution of primate social cognition is discussed.
