Pain Sensitivity and Affective Touch Perception: Evidence from Direct and Vicarious Experiences in Healthy...

As the skin serves as an interface between internal and external environments, pain and affective touch (AT) act as interoceptive and exteroceptive stimuli. Several studies have focused on these stimuli, independently evaluating pain or AT perception in direct or vicarious (observed) stimulation modalities. This study, instead, compared direct and vicarious perception of AT and pain, exploring their potential mutual influence in healthy individuals and patients with a high frequency or history of chronic migraine (CM).

Two identical experiments were conducted with 37 healthy volunteers and 37 CM patients. Participants underwent: (1) a psychometric assessment; (2) a quantitative sensory testing of direct pain thresholds and response to others' pain (vicarious pain); and (3) response to AT in direct and observed conditions.

In both populations, direct and observed AT elicited comparable hedonic responses. Compared to healthy controls, CM patients exhibited significantly higher pain thresholds and reduced vicarious pain sensitivity. No significant mutual influence or correlation was found between pain sensitivity and AT perception in either group.

Pain and AT perception show no association, likely reflecting their differing contextual roles: alerting to pain and interpersonal processing for AT. AT perception remains preserved in CM patients, indicating that hedonic touch mechanisms are resilient to chronic pain-induced alterations. The capacity of vicarious touch to evoke affective resonance comparable to direct physical contact might lay the basis for implementing future observation-based interventions for pain management in populations with cutaneous hypersensitivity, allodynia or those who dislike being touched.