What can head and facial movements convey about positive and negative affect?

We investigated whether the dynamics of head and facial movements apart from specific facial expressions communicate affect in infants. Age-appropriate tasks were used to elicit positive and negative affect in 28 ethnically diverse 12-month-old infants. 3D head and facial movements were tracked from 2D video. Strong effects were found for both head and facial movements. For head movement, angular velocity and angular acceleration of pitch, yaw, and roll were higher during negative relative to positive affect. For facial movement, displacement, velocity, and acceleration also increased during negative relative to positive affect. Our results suggest that the dynamics of head and facial movements communicate affect at ages as young as 12 months. These findings deepen our understanding of emotion communication and provide a basis for studying individual differences in emotion in socio-emotional development.