What do facial expressions of emotion express in young children? The relationship between facial display and EMG measures

The present paper explored the relationship between emotional facial response and electromyographic modulation in children when they observe facial expression of emotions. Facial responsiveness (evaluated by arousal and valence ratings) and psychophysiological correlates (facial electromyography, EMG) were analyzed when children looked at six facial expressions of emotions (happiness, anger, fear, sadness, surprise and disgust). About EMG measure, corrugator and zygomatic muscle activity was monitored in response to different emotional types. ANOVAs showed differences for both EMG and facial response across the subjects, as a function of different emotions. Specifically, some emotions were well expressed by all the subjects (such as happiness, anger and fear) in terms of high arousal, whereas some others were less level arousal (such as sadness). Zygomatic activity was increased mainly for happiness, from one hand, corrugator activity was increased mainly for anger, fear and surprise, from the other hand. More generally, EMG and facial behavior were highly correlated each other, showing a “mirror” effect with respect of the observed faces.