Premium
Hemispheric specialization in infant chimpanzees ( Pan troglodytes ): Evidence for a relation with gender and arousal
Author(s) -
Hopkins William D.,
Bard Kim A.
Publication year - 1993
Publication title -
developmental psychobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 93
eISSN - 1098-2302
pISSN - 0012-1630
DOI - 10.1002/dev.420260405
Subject(s) - laterality , psychology , arousal , developmental psychology , irritability , audiology , cognition , medicine , social psychology , neuroscience
The current study extends previous documentation of behavioral asymmetries in hand‐to‐mouth, self‐consoling behaviors of infant chimpanzees. The underlying source of lateralized hand‐to‐mouth, self‐calming behavior was investigated by comparing individual differences in neonatal arousal levels, regulatory ability, and motor performance with individual differences in the degree of laterality at 3 months. Asymmetrical hand‐to‐mouth, self‐calming behaviors at 3 months of age were significantly related to general arousal at 2 days of age (i.e., the Range of State cluster scores measured by the Brazelton Neonatal Behavioral Assessment Scale). Simply stated, chimpanzees with a right‐hand bias in hand‐to‐mouth behavior exhibited lower arousal at 2 days of age compared with nonright‐handed individuals. The only item of the Range of State cluster to distinguish subjects was irritability: Right‐handed subjects were less irritable. Previously, a trend was reported with respect to sex differences in the laterality of hand‐to‐mouth behavior. With the greater number of subjects in the present study, we found that females exhibited a significantly greater right‐hand bias for hand‐to‐mouth behaviors (12 of 13) than did males (9 of 15). We conclude that neonatal arousability, and not regulatory capacity or motor performance, predicts the degree of laterality found in hand‐to‐mouth, self‐calming behaviors in 3‐month‐old chimpanzees. These data are discussed from the standpoint of early pari‐parturitional or intrauterine factors affecting lateralized development. © 1993 John Wiley & Sons, Inc.