Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


The present study investigated the underlying dimensions of social behavior of infant monkeys. Three species of mother-infant dyad-reared monkeys were studied: crab-eating macaques (Macaca fascicularis), rhesus macaques (Macaca mulatta), and patas monkeys (Erythrocebus patas). In addition, the behavior of crab-eating macaques reared in mother-sibling-infant triads and in nuclear family triads was investigated. Independent maximum likelihood factor analyses of the mother-oriented and peer-oriented behavior of each of the five groups yielded seven factors, five of which were grossly similar across groups: social play, maternal comfort and care, affiliation, mother-oriented social play, and social exploration. The remaining two factors were not consistent among groups of infants. Simultaneous maximum likelihood factor analysis of all behaviors failed to demonstrate mathematical equivalence of the factor structures of the five groups of animals. In addition, simultaneous factor analysis of peer-oriented behaviors failed to replicate previous research findings of factors of hostility, social play, and fear-withdrawal. Although the findings of this study are consistent with previous research on the development of infant-mother and infant-peer affectional systems in nonhuman primates, the results are not consistent with previous factor analytic research in terms of the numbers and kinds of factors obtained. Because this study used a behavior classification system that consisted of a greater number of more specific behaviors than previous research, the factors that resulted are greater in number and more specific in nature than those yielded by previous studies.