How do Robot Touch Characteristics Impact Users’ Emotional Responses: Evidence from ECG and fNIRS

Robot touch is a vital interaction mode for emotional communication and human mental support in HRI. However, little is known about how robot touch characteristics influence the users’ subjective perception of emotion and physiological reactions. Therefore, a within-subject experiment of robot touches was conducted with the touch type (contact versus grip), length (long versus short), and location (hand versus forearm) as independent variables. The subjective perception was measured with PANAS scales. Electrocardiography (ECG) and functional near-infrared spectroscopy (fNIRS) were utilized to measure the participant’s cardiac autonomic nervous system responses and cerebral central nervous system responses. Results showed that touch type and length jointly affected users’ subjective perception of emotion and cerebral activity, and location affected users’ heart rate variability and cerebral activity. The results suggest that robot short-grip and long-contact behaviors might bring users more positive emotions. Although robot touch on forearms might not induce more positive emotional perception, it might be helpful for emotional regulation and might mobilize more cognitive resources.