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.