Motor simulation of multiple observed actions

Anticipated imitation of multiple agents

It is well-established that people tend to mimic one another's actions, a crucial aspect of social interactions. Anticipating imitation has been shown to boost motor activation and reaction times for congruent actions. However, prior research predominantly focused on dyads, leaving gaps in our knowledge regarding group dynamics. This study addresses this gap, conducting three experiments using extensive online data. Participants engaged in anticipated imitation tasks with one versus three virtual agents. The results across all three experiments (n = 77; n = 239; n = 457) consistently support the existence of an anticipated imitation effect, with faster reaction times for congruent actions. Furthermore, the research unveils a social facilitation effect, with participants reacting more swiftly when anticipating three agents compared to one. However, we did not find the expected increase of the congruency effect with multiple agents; rather, the data indicates that anticipating multiple agents instead decreases this effect. These findings are discussed within the framework of ideomotor theory, offering insights into how they relate to recent research on the automatic imitation of multiple agents.

EEG Frequency Tagging Reveals the Integration of Form and Motion Cues into the Perception of Group Movement

The human brain has dedicated mechanisms for processing other people’s movements. Previous research has revealed how these mechanisms contribute to perceiving the movements of individuals but has left open how we perceive groups of people moving together. Across three experiments, we test whether movement perception depends on the spatiotemporal relationships among the movements of multiple agents. In Experiment 1, we combine EEG frequency tagging with apparent human motion and show that posture and movement perception can be dissociated at harmonically related frequencies of stimulus presentation. We then show that movement but not posture processing is enhanced when observing multiple agents move in synchrony. Movement processing was strongest for fluently moving synchronous groups (Experiment 2) and was perturbed by inversion (Experiment 3). Our findings suggest that processing group movement relies on binding body postures into movements and individual movements into groups. Enhanced perceptual processing of movement synchrony may form the basis for higher order social phenomena such as group alignment and its social consequences.

Motor simulation is disturbed when experiencing pain

While the contribution of social processes to pain perception is well documented, surprisingly little is known about the influence of pain on social perception. In particular, an important question is how pain modulates the processing of other people's actions. To address this question, the current study tests, using automatic imitation, the hypothesis that pain interferes with motor simulation-that is, the processing of observed actions in the motor system. Participants in both experiments performed an automatic imitation task requiring them to abduct their index or little finger while they saw someone else performing either a congruent or incongruent action. Automatic imitation was measured in a pain-free context, a context where pain was coupled to the execution of a movement (experiment 1), and a context where pain occurred randomly (experiment 2). The results revealed that automatic imitation, indexed by slower responses on incongruent compared with congruent trials, was reduced when experiencing pain, both when pain was linked to movement execution and when it was not. Thus, the current study shows that pain leads to reduced motor processing of others' behavior and, as such, has important implications for understanding the social difficulties associated with pain.