title: The influence of Oxytocin on automatic motor simulation.
abstract: Motor simulation is important for imitation, action understanding, and a wide range of social cognitive skills. Furthermore, the neuropeptide hormone Oxytocin (OT) has also been related to social information processing in humans, improving perception of social stimuli and increasing altruism and trust. Surprisingly, however, a direct link between OT and motor simulation has never been systematically investigated. The current study examined this question using the imitation-inhibition task, a paradigm used to investigate automatic imitation behaviour and motor simulation. In this task, participants carry out simple finger movements while observing irrelevant movements that either match (congruent condition) or do not match (incongruent condition) the instructed movements. In a double-blind, placebo-controlled design, male participants were administered either OT (N=24) or placebo (N=24), and subsequently performed the imitation-inhibition task. To ensure specificity of OT effects to imitative behaviour, participants additionally performed a Stroop colour-word interference task (adapted to optimize similarities with the imitation inhibition task) to rule out general effects on cognitive control. As predicted, OT selectively influenced the congruency effect in the imitation-inhibition task but not the congruency effect in the Stroop task. This effect showed that OT led to a larger congruency effect by slowing down reaction times on incongruent trials when observed and own actions did not match. The findings suggest that OT leads to a decrease of control over automatic imitative behaviour mediated by increased self-other merging. Thus, for the first time, a link between OT and motor simulation is demonstrated, providing a window into the role of OT in motoric aspects of social cognition.
authors.affiliation: Department of Experimental Psychology, Ghent University, B-9000 Ghent, Belgium. Electronic address: Lize.DeCoster@UGent.be.
authors.forename: Lize
authors.initials: L
authors.lastname: De Coster
authors.affiliation: Department of Experimental Clinical and Health Psychology, Ghent University, B-9000 Ghent, Belgium.
authors.forename: Sven C
authors.initials: SC
authors.lastname: Mueller
authors.affiliation: Department of Endocrinology, Ghent University Hospital, B-9000 Ghent, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: T'Sjoen
authors.affiliation: Department of Experimental Clinical and Health Psychology, Ghent University, B-9000 Ghent, Belgium.
authors.forename: Lien
authors.initials: L
authors.lastname: De Saedeleer
authors.affiliation: Department of Experimental Psychology, Ghent University, B-9000 Ghent, Belgium; Radboud University, NL-6525 Nijmegen, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Brass
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000187:drug effects*; D004311:Double-Blind Method; D006801:Humans; D007100:Imitative Behavior / Q000187:drug effects*; D007266:Inhibition, Psychological; D008297:Male; D009483:Neuropsychological Tests; D010121:Oxytocin / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D055815:Young Adult
chemical_list: D010121:Oxytocin
keywords: Automatic imitation; Mirror neuron system; Motor simulation; Oxytocin; Self-other distinction