Investigating the Relationship Between Motor Resonance and Nonconscious Mimicry

Motor resonance refers to the mirroring of observed actions in one’s own motor system. It is possible that motor resonance is the neural mechanism underlying nonconscious mimicry (NCM)—the ubiquitous phenomenon wherein people mimic the behaviour of interaction partners (Chartrand & Bargh, 1999). Previous research has shown that priming interdependent selfconstrual (interSC) increases mimicry (van Baaren et al., 2003). If motor resonance is the mechanism underlying NCM, then a manipulation known to facilitate mimicry (i.e. interSC) should increase motor resonance. In experiment one, we variably primed independent selfconstrual (indSC)—known to inhibit mimicryv—and interSC in a motor priming paradigm. Participants observed videos of a hand squeezing a rubber ball hard or soft, which contained indSC and interSC prime words that changed colour to elicit a pre-instructed hard or soft squeeze response. The results indicated that when an observed action was incongruent with the required response, reaction time (RT) was slowed and electromyographic (EMG) activity was significantly modulated in the direction of the incongruence. Importantly, the RT cost and EMG modulation were significantly larger during the presentation of interSC primes. In experiment two, we used a more direct measure of motor resonance—motor-evoked potentials (MEPs) evoked with transcranial magnetic stimulation (TMS). Additionally, experiment two contained a dyadic interaction designed to elicit NCM at the beginning of the experimental session. Following the dyad, participants passively observed the same action videos used in experiment one, which contained interSC, indSC, or no prime words. Whilst participants observed the videos, MEPs were induced in the primary muscle underlying the action. The results from experiment two displayed a moderate positive correlation between NCM and motor resonance, as well as a significant effect of self-construal priming on MEP amplitude. Overall, the results from experiments one and two converge to show that activating interSC induces hyper-motor resonance (and in fact, priming indSC induces hypo-motor resonance). Since interSC is also known to increase mimicry, our findings empirically link motor resonance and NCM. To qualify this statement, however, we found only a moderate correlation between mimicry and motor resonance in experiment two, suggesting that motor resonance, in the absence of social information, may not be enough to elicit mimicry on its own. Rather, in line with the social psychological literature on NCM, it is likely that a host of social, cognitive, affective, motivational and attitudinal factors combine with the basic motor resonance system to produce mimicry