Orientation to social and nonsocial stimuli in neonatal chimpanzees and humans

The behavioral capabilities of neonatal chimpanzees ore not well known. A ma(or goal of this study was to document their ability to orient to social and nonsocial objects and to compare their performance with that of human infants. The Brozelton Neonatal Behavioral Assessment Scale (NBAS) was administered to 13 nursery-reared chimpanzees, every other day during their first month of life, and to 42 humans, twice, on the third and thirtieth day of life. The orientation items included social stimuli (a human face and both human and chimpanzee sounds) and nonsocial stimuli [a red ball and a red rattle). Repeated-measures analysis of variance on the orientation cluster of the NBAS revealed that chimpanzee neonates have the capacity for sustained attention to all stimuli, both social and nonsocial, indistinguishable from that of human neonates. Significant improvements in orientation performance from Day 2 to Day 30 were found for both species. These striking similarities in early orientation ability are viewed as a challenge to notions of unique human propensities.