Touching virtual humans: Haptic responses reveal the emotional impact of affective agents

Interpersonal touch is critical for social-emotional development and presents a powerful modality for communicating emotions. Virtual agents of the future could capitalize on touch to establish social bonds with humans and facilitate cooperation in virtual reality (VR). We studied whether the emotional expression of a virtual agent would affect the way humans touch the agent. Participants were asked to hold a pressure-sensing tube presented as the agent's arm in VR. Upon seeing the agent's emotional expression change, participants briefly squeezed the arm. The effect of emotional expressions on affective state was measured using self-reported valence and arousal as well as physiology-based indices. Onset, duration, and intensity of the squeeze were recorded to examine the haptic responses. Emotional expression of agents affected squeeze intensity and duration through changes in emotional perception and experience. Haptic responses may thus provide an implicit measure of persons' experience towards their virtual companion.