title: Postural modulation induced by pictures depicting prosocial or dangerous contexts.
abstract: The ability to identify safety and danger is critical to survival. However, not much is known about human somatic body reactions in these contexts. We performed a posturographic study comparing body reactions to the sight of pictures of smiling babies and families (affiliative) versus matched neutral people, and to pictures depicting body envelope violations (mutilation) versus matched neutral people. The participants stood on a force platform and heart rate and displacement of the center of pressure were recorded while the pictures were presented. Pictures of mutilation induced a freezing-like reaction consisting of a medial-lateral (M-L) decrease in the amplitude of sway (immobility) and increase of the mean power frequency (rigidity), associated with bradycardia. Affiliative stimuli also induced an immobility and rigidity behavior but in the anterior-posterior (A-P) axis. This resembles the "immobility-without-fear reaction" proposed to occur when, upon detection of safety cues, mammals including humans are involved in pro-social activities. We conclude that the sight of visual cues of affiliation and danger produce distinct body somatic reactions.
authors.affiliation: Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Av. Brigadeiro Trompowsky s/n, Ilha do Fundão, Rio de Janeiro 21949-900, Brazil.
authors.forename: Lívia Dumont
authors.initials: LD
authors.lastname: Facchinetti
authors.forename: Luis Aureliano
authors.initials: LA
authors.lastname: Imbiriba
authors.forename: Tatiana Maia
authors.initials: TM
authors.lastname: Azevedo
authors.forename: Claudia Domingues
authors.initials: CD
authors.lastname: Vargas
authors.forename: Eliane
authors.initials: E
authors.lastname: Volchan
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography / Q000379:methods; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*