Neonatal Imitation of Adults

Neonatal imitation is the act of doing the same movement (usually a facial expression) after seeing it performed by a social partner. This is not a human-unique capacity. Neonatal imitation of adults is experimentally tested by making specific facial expressions at infants directly after birth (i.e., mouth opening and tongue protrusion) and measuring whether the infant imitates by making the same facial expression. This capacity for early imitation of facial expressions represents the biological underpinnings of the set of important social cognitive capacities that humans and great apes possess. Imitation plays a crucial role in transmission of culture and facilitating social bonds. Neonatal imitation is distinct from other later forms of imitation, and seems to be largely reflexive, as the early ability to match facial expressions is inhibited at around 2-3 months of age when other infantile reflexes start to fade. This ability is driven by the capacity of infants to cross-modally process visual and motor information and to detect the equivalent motor response. The capacity for neonatal imitation has been demonstrated in all populations tested thus far, even outside of the commonly tested Western, educated, industrialized, rich, and democratic cultures. For example, observations of Nepalese infants one hour post-partum demonstrated that they could imitate the facial expressions of an experimenter.

There is empirical evidence for facial imitation of adult humans in one-week-old chimpanzees, even after being reared by their biological mothers. There is also evidence for imitation of facial expression on the first day of life in newborn rhesus macaques. Importantly, the capacity for early facial imitation disappeared after two months, just as in humans, suggesting that this is an innate, reflexive capacity. The mechanism underlying human imitation for complex actions later in development is likely different from that which underlies neonatal imitation of facial expressions, which is shared between humans, chimpanzees, and other primates. The capacity for neonatal facial imitation emerged before the human lineage split from that of old world primates, while other more complex social-cognitive capacities emerged much later in homo erectus.