Automatic attribution of social coordination information to chasing scenes: evidence from mu suppression

This study explored whether social coordination information that extends beyond individual goals is attributed to impoverished movements produced by simple geometric shapes. We manipulated coordination information by presenting two chasers and one common target performing coordinated or individual (i.e., uncoordinated) chases, and measured mu rhythms (electroencephalogram oscillations within the 8-13 Hz range at sensorimotor regions) related to understanding social interactions. We found that although the participants' task was completely unrelated to processing chasing motion, mu rhythms were more suppressed for coordinated chasing than in the control condition (backward replay for chasing motion), and this effect disappeared for uncoordinated chasing. Moreover, mu suppression increased with higher post-test ratings of social coordination but did not correlate with uncoordinated information. Such effects cannot be explained by general attentional involvement, as there was no difference in attention-related occipital alpha suppression across conditions. These findings are consistent with interpretations of processing coordinated actions, suggesting that our visual system can automatically attribute social coordination information to motion, at least in chasing scenes.