Eye contact enhances interpersonal motor resonance: comparing video stimuli to a live two-person action context.

Previous research has shown a link between eye contact and interpersonal motor resonance, indicating that the mirroring of observed movements is enhanced when accompanied with mutual eye contact between actor and observer. Here, we further explored the role of eye contact within a naturalistic two-person action context. Twenty-two participants observed simple hand movements combined with direct or averted gaze presented via a live model in a two-person setting or via video recordings, while transcranial magnetic stimulation was applied over the primary motor cortex (M1) to measure changes in M1 excitability. Skin conductance responses and gaze behavior were also measured to investigate the role of arousal and visual attention herein. Eye contact significantly enhanced excitability of the observer's M1 during movement observation within a two-person setting. Notably, participants with higher social responsiveness (Social Communication subscale of the Social Responsiveness Scale) displayed a more pronounced modulation of M1 excitability by eye gaze. Gaze-related modulations in M1 excitability were, however, not associated with differences in visual attention or autonomic arousal. In summary, the current study highlights the effectiveness and feasibility of adopting paradigms with high ecological validity for studying the modulation of mirror system processes by subtle social cues, such as eye gaze.