Analysis of entrainment in face-to-face interaction using heart rate variability

The entrainment between talkers in face-to-face interaction plays an important role in the smooth exchange of information. In this paper, the physiological signal entrainment in face-to-face interaction was analyzed on the basis of heart rate and its variability as indices, based on the previous known fact that alteration of cardiac rhythm has been used as an indicator of the emotional state. The subjects consisted of two pairs of mothers and healthy infants aged 5 and 9 months as a primitive form of communication, and one pair of male students. The existence of physiological signal entrainment was demonstrated from some examples of synchronized time changes of heart rate variability in both mother-infant interaction and adult conversation. This finding suggests the entrainment is biologically essential to human communication and it could be applicable for improved human-robot interaction