Mirror-induced social facilitation in stumptailed macaques (Macaca arctoides)

Seven adult female stumptailed macaques (Macaca arctoides) were confronted alternately with their reflection in a mirror and with the mirror covered. The reflection elicited significantly more visual attention and social responding than the control stimulus, replicating previous findings. Mirror-image stimulation did not significantly affect the subjects' manipulation of unfamiliar objects, but it did increase bout-lengths of episodes of drinking from a bottle containing orange juice. Possible explanations for the ability of the mirror to induce social facilitation of drinking but not of object manipulation are discussed, along with possible underlying mechanisms. Mirror-induced social facilitation is further evidence that monkeys interpret their reflection as a conspecific.