The effect of threat information on acquisition, extinction, and reinstatement of experimentally conditioned fear of movement-related pain

OBJECTIVE: The experiential acquisition of pain-related fear has been demonstrated by pairing a painful electrocutaneous stimulus pain-US; unconditioned pain stimulus) with one movement (CS+; conditioned stimulus) but not with another (CS-). However, it is expected that during acquisition through direct experience, pain-related fear can be intensified or weakened by verbally/visually transmitted information about the pain and its meaning. METHOD: Participants received threatening information (US-inflation), safety information (US-deflation), or no information about the pain-US (US-same). Additionally, we measured return of fear after a reinstatement procedure: two unsignaled pain-USs were presented in the experimental groups, but not in the control groups. RESULTS: We replicated the acquisition and extinction of experimentally induced fear of movement-related pain in healthy subjects both in the verbal reports and the eye-blink startle measures. Two reinstating pain-US presentations led to a differential return of self-reported fear and a nondifferential return of fear in the eye-blink startle responses. Although, we failed to find an effect of verbal/visual information regarding the meaning of the pain-US on the acquisition, extinction, or reinstatement of pain-related fear, we did observe a pain sensitization effect over time suggesting that our threat manipulation induced an increase of perceived threat in all groups. CONCLUSION: The results suggest that our threat manipulation might not have worked or that it was not sensitive enough to yield group-specific effects. We replicated acquisition, extinction, and return of experimentally conditioned fear of movement-related pain, but the threat manipulation failed to generate any additional effects.