Author:

Keywords:

eye contact, interpersonal motor resonance, TMS, oxytocin

Abstract:

Introduction. An individual’s propensity to engage in or avoid interactions with others often depends on the social context. Among different social cues from the environment, the eyes constitute a very salient source for initiating social interaction. Accordingly, using transcranial magnetic stimulation (TMS), previous work from our lab has demonstrated that direct eye contact between two individuals can readily evoke an increased propensity to ‘mirror’ other peoples’ actions. As such, motor resonance can be considered as a neurophysiological measure of the propensity to ‘approach’ other people. Besides social cues from the environment, also the neuropeptide oxytocin is suggested to play a pivotal role in modulating the decision between approach and avoidance behaviors, as it is known to promote prosocial behavior and the accurate appraisal of socially-relevant stimuli (such as eye gaze). With the present study, we aimed to investigate the interplay between oxytocin administration and mutual eye contact on motor resonance during the observation of movement. Method. Twenty-six neurotypical adult males (18-29y) participated in a double-blind placebo-controlled cross-over design. The trail consisted out of two sessions, in which participants were administered a single dose (24 IU) of either placebo or oxytocin nasal spray, with a wash-out period of one week in between sessions. After nasal spray administration, TMS was used to measure changes in motor resonance at the level of the primary motor cortex while participants observed video stimuli of an actress performing simple hand movements combined with either direct or averted gaze. Additionally, eye tracking was performed to evaluate potential changes in spontaneous viewing behavior of the participants. Results. Our results showed that motor resonance upon movement observation is tentatively enhanced when mutual eye contact is established between the observer and the observed model, indicating that direct eye gaze can form a salient social cue to promote motor resonance or ‘approach’. This facilitating effect of eye contact depended however on inter-individual variations in self-reports of attachment avoidance (State Adult Attachment Measure; SAAM), such that only in participants with low attachment avoidance, motor resonance was significantly enhanced by direct eye gaze, whereas in participants with high attachment avoidance, the facilitating effect of eye contact was absent. Interestingly, after a single dose of intranasal administered oxytocin, the facilitating effect of eye contact on motor resonance also emerged in the individuals with high attachment avoidance, Conclusion. Our results provide indications that exogenously administered oxytocin can promote the propensity of an otherwise ‘avoidant’ individual to engage in motor resonance or ‘approach’ upon direct eye gaze. Particularly, oxytocin may increase the saliency of social cues such as direct eye gaze, which in turn may promote the tendency of an individual to automatically mirror the behaviors of the sender of the direct gaze. Overall, these findings stimulate future investigations on the potential of oxytocin therapy for targeting eye contact avoidance in patient populations with particular implications in this domain, such as autism spectrum disorders.