Hand preferences for simple reaching in juvenile chimpanzees (Pan troglodytes): Continuity in development.

Abstract

Hand preferences were assessed in 51 chimpanzees (Pan troglodytes; 28 male and 23 female) ranging from 2 to 5 years of age). Simple reaching served as the measure of lateral bias in hand preference during 2 assessments separated by I year. A significant sex by hand preference interaction was found with a greater prevalence of right-handed males than females. No significant differences were found between age and either strength or direction of hand preference. A significant interaction was found between rearing and strength of hand preference. Mother-reared chimpanzees showed significantly greater strength in hand preference than nursery-reared chimpanzees. Finally, a significant positive correlation was found between tests of hand preference conducted over a I-year interval. These data suggest that in chimpanzees hand preferences are established by 2 years of age and are stable throughout the juvenile developmental period.