Poster C123, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Covert simulation of others' actions in real-time
Julia Hamilton1, Aleksandra Sherman1; 1Occidental College
Recent research points to the importance of a mirror-neuron system (MNS) in the perception and accurate prediction of action. We sought to test the hypothesis that individuals recruit the MNS during action prediction such that they are covertly simulating other’s action in real-time. We measured neural activity using high-density electroencephalograpy, while participants viewed videos of point-light displays (PLDs) depicting upright humans, inverted humans, and animals, followed by an occluder that appeared for either 100ms or 700ms. Participants were then shown a static test posture and tasked with determining whether it was a continuation of the action in the same depth orientation. We varied whether the time between the static test posture and the endpoint of the PLD video corresponded with or did not correspond with the occluder time. Prediction accuracy was significantly higher for upright PLDs, with larger N170s, relative to inverted humans and animals. Interestingly, our neurophysiological data suggests that participants detected differences between corresponding and non-corresponding actions for upright displays, reflected in a larger observer error-related negativity at central sites peaking around 500ms. Additionally, we observed marginally stronger mu-suppression at central sites for corresponding relative to non-corresponding upright displays, indicating involvement of the MNS. Surprisingly, these differences were not reflected behaviorally. Together, our results support the notion that action prediction may be enhanced by one's ability to perform and therefore simulate the observed action. We argue that individuals are indeed covertly simulating others actions, but that this real-time simulation mechanism may be only weakly recruited for PLDs.
Topic Area: PERCEPTION & ACTION: Vision