Neonatal Imitation and Gaze Following in Rhesus Macaques

Infant rhesus macaques (Macaca mulatta) participated in the neonatal imitation assessment between 1–8 days of age and in a gaze following assessment at approximately 7 months of age (M = 234 days, SD = 15). Subjects included singly housed surrogate-reared, low-socialization infants (n = 61; 28 females), and peer-reared, high-socialization infants (n = 58, 23 females). On the day of birth, infants were separated from their mothers and raised in a primate nursery. Infants were raised identically for the first five weeks. Once the youngest infant reached 37 days of age, infants were placed into groups. High-socialization infants were raised in groups of three to five peers. Low-socialization infants were individually housed, assigned to playgroups composed of three to four peers housed together two hours a day, five days a week. See Supplemental Materials for details.