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

Abstract

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.

Keywords: action observation; eye contact; mirror neuron system; skin conductance; transcranial magnetic stimulation (TMS).

Fig. 1

(A) Schematic overview of the experimental set-up in the video (left panel) and live (right panel) presentation mode. (B) Factorial design and stimuli showing the stimulus person (experimenter J.P.) engaging in mutual eye contact (direct gaze) or not (averted gaze) while performing either a simple finger abduction movement or no movement. The last still of each condition is depicted. (C) Single-pulse TMS was delivered 3 seconds after the onset of each video clip (in the video presentation mode) or after the opening of the LC screen (in the live presentation mode), which corresponded to the execution phase of the observed movement.

Fig. 2

The effect of perceived eye gaze (direct, averted) and presentation mode (live, video) on MEP peak-to-peak amplitude, per observational condition (upper panels: gaze and motor cues; lower panels: gaze cues only) and muscle (left panels: experimental FDI muscle; right panels: control ADM muscle). ^**P < 0.001, error bars denote mean ± SE.

Fig. 3

(A) Magnitude of the average skin conductance response per presentation mode and observed gaze direction (averaged across movement observation conditions). ^**P < 0.001, error bars denote mean ± SE. (B) The relationship between the eye contact effect on M1 excitability and the eye contact effect on autonomic arousal was not significant. (C) Opposite modulatory effects were noted for the association between the SRS Social Communication score (higher scores denote more impairments) and the eye contact effect on M1 excitability (left panel; negative correlation) and autonomic arousal (right panel; positive correlation). Dotted lines denote 95% CI.

Fig. 4

Effect of observed gaze direction and presentation mode on average fixation duration (upper panels) and number of fixations (lower panels) to the ‘eyes’ area of interest (AOI). ^*P < 0.05, error bars denote mean ± SE.