Neural tracking of biological motion rhythms in early infancy: links to caregiver touch-related behaviours and attitudes

Infant environments are rich in rhythms, many of which are social in nature. These rhythms are proposed to play an important role in early communication and interpersonal synchrony. In this cross-sectional electroencephalography (EEG) study with 3- and 6-month-olds (n=31 and n=30, respectively), we examined whether the infant brain tracks the rhythmicity of locomotion-related biological motion in the visual domain and which experiential factors relate to this ability. We found robust neural tracking of biological motion rhythms at both ages, with no effects of age or orientation (upright or inverted). Additionally, we found that caregiver-reported practice of infant carrying/babywearing and caregiver attitudes toward social touch were linked to infant neural tracking of biological motion rhythms, particularly in the inverted condition. Finally, exploratory analyses revealed a lateralisation effect, whereby the left hemisphere processed rightward (vs. leftward) biological motion rhythms more strongly. Our findings suggest that from early on, the infant brain tracks the rhythmicity of whole-body biological motion. Furthermore, caregiver touch-related practices, particularly infant carrying/babywearing, may play a role in infant neural tracking of socially-relevant rhythms.