Analgesic effect of robotic stroking with speech

In medical and nursing care settings, stroking with speech, which combines physical touch with verbal communication, is extensively employed to enhance positive outcomes, such as anxiety relief and analgesia. Although human-robot interaction studies have demonstrated that robotic stroking with speech elicits stronger positive emotions than stroking or speaking alone, only a few studies have quantitatively verified its analgesic effects. This study investigates whether robotic stroking with speech modulates pain perception. Using the gate control theory as an interpretive framework, we examined whether this multimodal interaction increases pain thresholds and exceeds the effect of stroking only. In an experiment with 37 healthy volunteers, pain thresholds were measured under conditions of No Interaction, Stroking Only, and Stroking with Speech via electrical stimulation. The results revealed that Stroking Only and Stroking with Speech significantly increased the pain thresholds compared with the No Interaction condition. Notably, Stroking with Speech produced a significantly higher threshold than Stroking Only. These findings demonstrate that the benefits of robotic stroking with speech extend to the modulation of pain perception, highlighting its potential as an effective nonpharmacological intervention for pain relief.