Attending to behaviour versus attending to knowledge: examining monkeys' attribution of mental states

Abstract

The ability of monkeys to attribute mental states such as ignorance to each other was examined in two experiments using four captive groups of Japanese and rhesus macaques, Macaca fuscata and M. mulatta. In the first experiment, females were shown food or a predator, either in the presence of their offspring or alone, to determine whether they would attempt to alert ignorant offspring more than knowledgeable ones. The behaviour of mothers appeared to be unaffected by the knowledge of their offspring. In the second experiment, a juvenile offspring of a dominant female was isolated in an enclosure with a normally subordinate adult female while the juvenile's mother sat nearby behind either a glass barrier, an opaque barrier or a one-way mirror. In the mirror condition, the two subjects could see the mother, but she could not see them. The behaviour of subjects under the mirror condition was intermediate between that under the glass and opaque conditions. Subjects were probably sensitive to the mother's orientation and attentiveness, but there was no evidence that they recognized the difference between their own visual perspective and that of the mother.