Early Social Experience Affects Neural Activity to Affiliative Facial Gestures in Newborn Nonhuman Primates.
Level 5 - mechanism / opinion, no new human data
Animal research (nonhuman primate model)
PubMed 26022835 · doi:10.1159/000381538
What was done
Researchers compared 3-day-old rhesus macaques raised either with their biological mothers or in a nursery without mothers. They recorded electroencephalography (EEG) mu rhythm desynchronization (5–7 Hz alpha band) and evaluated neonatal imitation behavior while infants observed and produced affiliative facial gestures (lipsmacking), non-affiliative gestures (tongue protrusion), and a nonsocial control stimulus.
What was found
The abstract reports no exact numbers, effect sizes, or p-values. Directionally, mother-reared infants showed a significantly higher likelihood of imitating lipsmacking gestures and displayed greater mu rhythm desynchronization during lipsmacking observation than nursery-reared infants. These differences were absent during exposure to tongue protrusion or the nonsocial control.
Why it matters
This study provides evidence that early postnatal social experience rapidly shapes the neural systems underlying action perception and imitation in primates within days of birth.
Limits
The abstract does not state the sample size, exact statistical values, or effect sizes. As an animal study in 3-day-old macaques, findings may not fully translate to human developmental trajectories, and long-term persistence of the neural differences was not evaluated.
Cited by
- supports Lip-smacking is an affiliative social behavior in monkeys.