Look at Me: Early Gaze Engagement Enhances Corticospinal Excitability During Action Observation

Abstract

Direct gaze is a powerful social cue able to capture the onlooker’s attention. Beside gaze, head and limb movements as well can provide relevant sources of information for social interaction. This study investigated the joint role of direct gaze and hand gestures on onlookers corticospinal excitability (CE). In two experiments we manipulated the temporal and spatial aspects of observed gaze and hand behavior to assess their role in affecting motor preparation. To do this, transcranial magnetic stimulation (TMS) on the primary motor cortex (M1) coupled with electromyography (EMG) recording was used in two experiments. In the crucial manipulation, we showed to participants four video clips of an actor who initially displayed eye contact while starting a social request gesture, and then completed the action while directing his gaze toward a salient object for the interaction. This way, the observed gaze potentially expressed the intention to interact. Eye tracking data confirmed that gaze manipulation was effective in drawing observers’ attention to the actor’s hand gesture. In the attempt to reveal possible time-locked modulations, we tracked CE at the onset and offset of the request gesture. Neurophysiological results showed an early CE modulation when the actor was about to start the request gesture looking straight to the participants, compared to when his gaze was averted from the gesture. This effect was time-locked to the kinematics of the actor’s arm movement. Overall, data from the two experiments seem to indicate that the joint contribution of direct gaze and precocious kinematic information, gained while a request gesture is on the verge of beginning, increases the subjective experience of involvement and allows observers to prepare for an appropriate social interaction. On the contrary, the separation of gaze cues and body kinematics can have adverse effects on social motor preparation. CE is highly susceptible to biological cues, such as averted gaze, which is able to automatically capture and divert observer’s attention. This point to the existence of heuristics based on early action and gaze cues that would allow observers to interact appropriately.

The neuroscience of social feelings: mechanisms of adaptive social functioning

“…For example, social stimuli can attract first saccades more frequently along with a larger portion of visual attention to scenes ( Rosler et al, 2017 ). Direct gaze can act as a type of prime for socially-relevant actions, particularly when combined with precise body movements that engage interaction ( Betti et al, 2018 ). Furthermore, viewing patterns of social stimuli (for own species and cross-species) were discovered to be individual and species-specific in human and nonhuman primates, and possibly based on natural characteristics as well as experiential factors that develop through adaptation ( Kano et al, 2018 ).…”

In the eye of the beholder: Social traits predict motor simulation during social gaze

“…In support of this notion, a series of cognitive-behavioral studies adopting a stimulus-response compatibility task demonstrated that observed movements were mimicked faster if the interaction partner established eye contact with the participant during congruent, but not during incongruent motor responses (Wang, Newport, et al, 2011;Wang, Ramsey, et al, 2011;Wang & Hamilton, 2014). These behavioral results were corroborated with neural activation (Wang, Ramsey, et al, 2011) and neurophysiological studies adopting transcranial magnetic stimulation (TMS) and/or electroencephalography (EEG), consistently showing that neural motor resonance is enhanced upon the observation of motor acts accompanied by direct compared to averted gaze from the actor (Betti et al, 2018(Betti et al, , 2019Prinsen et al, 2017Prinsen et al, , 2018. Together, these findings demonstrate that perceived eye contact readily increases the observer's propensity to resonate with the actions of others and that interpersonal motor resonance is generally modulated in a socially adaptive way, i.e.…”

“…Previous studies have consistently demonstrated that during passive action observation, eye contact between performer and observer readily increases the observer's propensity to internally simulate or 'mirror' these actions (Betti et al, 2018(Betti et al, , 2019Prinsen et al, 2017Prinsen et al, , 2018. The present study examined whether and how individual differences in social functioning is associated with their ability to show socially adaptive interpersonal motor resonance in a large representative sample of 124 participants.…”

Re-enacting the Bodily Self on Stage: Embodied Cognition Meets Psychoanalysis

“…In recent years, interesting work has been conducted on social cognition. Pioneering research has shown that newborns come into the world wired to socially interact (Castiello et al., 2010) and that is possible to quantify the specific contribution of direct gaze and kinematic information on subjective involvement during interactions (Betti et al., 2018). Moreover, the problem of direct social perception has been reframed in terms of establishing a measurable relationship between movement features and perceived mental states (Becchio et al., 2018).…”