title: Attention effects on vicarious modulation of nociception and pain.
abstract: The observation of others' facial expressions of pain has been shown to facilitate the observer's nociceptive responses and to increase pain perception. We investigated how this vicarious facilitation effect is modulated by directing the observer's attention toward the meaning of pain expression or the facial movements. In separate trials, participants were instructed to assess the "intensity of the pain expression"(meaning) or to "discriminate the facial movements" in the upper vs lower part of the face shown in 1-second dynamic clips displaying mild, moderate, or strong pain expressions or a neutral control. In 50% of the trials, participants received a painful electrical stimulation to the sural nerve immediately after the presentation of the expression. Low-level nociceptive reactivity was measured with the RIII-response, and pain perception was assessed using pain ratings. Pain induced by the electrical stimulation increased after viewing stronger pain expressions in both tasks, but the RIII-response showed this vicarious facilitation effect only in the movement discrimination task at the strongest expression intensity. These findings are consistent with the notion that vicarious processes facilitate self-pain and may prime automatic nociceptive responses. However, this priming effect is influenced by top-down attentional processes. These results provide another case of dissociation between reflexive and perceptual processes, consistent with the involvement of partly separate brain networks in the regulation of cortical and lower-level nociceptive responses. Combined with previous results, these findings suggest that vicarious pain facilitation is an automatic process that may be diminished by top-down attentional processes directed at the meaning of the expression.
authors.affiliation: Research Group on Health Psychology, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium. Electronic address: Ali.khatibi@gmail.com.
authors.forename: Ali
authors.initials: A
authors.lastname: Khatibi
authors.affiliation: Departement de Psychologie, Université de Montréal, Montréal, Quebec, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, Quebec, Canada.
authors.forename: Etienne
authors.initials: E
authors.lastname: Vachon-Presseau
authors.affiliation: Research Group on Health Psychology, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium; Center for Health and Medical Psychology, Örebro University, Örebro, Sweden.
authors.forename: Martien
authors.initials: M
authors.lastname: Schrooten
authors.affiliation: Research Group on Health Psychology, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium; Department of Clinical Psychological Science, Maastricht University, Maastricht, The Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: Vlaeyen
authors.affiliation: Departement de Psychologie, Université de Montréal, Montréal, Quebec, Canada; Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, Quebec, Canada; Groupe de Recherche sur le Systeme Nerveux Central (GRSNC), Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Rainville
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D004558:Electric Stimulation; D004645:Empathy / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059225:Nociception / Q000502:physiology*; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D012938:Social Perception; D055815:Young Adult
keywords: Attentional modulation; Facial expression of pain; Nociceptive flexion reflex; Pain perception; Vicarious facilitation