Caregiver mirroring as a foundation for facial feedback mechanisms in emotion perception.

The facial feedback hypothesis suggests that facial muscle activity contributes to emotion perception, but the developmental origins of this mechanism remain underspecified. This theoretical paper argues that caregiver mirroring - specifically caregivers' contingent imitation of infant facial expressions - plays a critical role in establishing the facial feedback mechanism. Drawing on previous empirical findings, we propose that repeated episodes of being mirrored provide infants with reliable sensorimotor contingencies linking facial action, proprioceptive feedback, and emotional states. We further consider situations that impede caregiver mirroring - such as infant dummy (pacifier) use and caregiver botulinum toxin (Botox) treatment - as naturalistic perturbations of these contingencies. This paper highlights how caregiver facial mirroring may scaffold infants' developing emotion processing, offering a socially embedded perspective on the early development of embodied emotional understanding.