title: Biomechanical organization of gait initiation depends on the timing of affective processing.
abstract: Gait initiation (GI) from a quiet bipedal posture has been shown to be influenced by the emotional state of the actor. The literature suggests that the biomechanical organization of forward GI is facilitated when pleasant pictures are shown, as compared to unpleasant pictures. However, there are inconsistencies in the literature, which could be due to the neural dynamics of affective processing. This study aimed to test this hypothesis, using a paradigm whereby participants initiated a step as soon as they saw an affective picture (i.e., onset), or as soon as the picture disappeared from the screen (i.e., offset). Pictures were a priori categorized as pleasant or unpleasant, and could also vary in their arousing properties. We analyzed center-of-pressure and center-of-gravity dynamics as a function of emotional content. We found that gait was initiated faster with pleasant images at onset, and faster with unpleasant images at offset. Also, with offset GI the peak velocity of the COG was reduced, and subjects took smaller steps, with unpleasant images relative to pleasant images. The results are discussed in terms of current knowledge regarding temporal processing of emotions, and its effects on GI.
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands. Electronic address: j.stins@fbw.vu.nl.
authors.forename: John F
authors.initials: JF
authors.lastname: Stins
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Linda M A
authors.initials: LM
authors.lastname: van Gelder
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Oudenhoven
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Beek
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology*; D000704:Analysis of Variance; D001696:Biomechanical Phenomena / Q000502:physiology; D001837:Body Weights and Measures / Q000295:instrumentation / Q000379:methods; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007389:Internal-External Control; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D004856:Postural Balance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values
keywords: Balance; Center-of-pressure; Emotion; Gait initiation