How choice and motor mimicry affect affiliation: An fNIRS study

It is widely believed that being mimicked causes liking and social bonding, but the underlying neural mechanisms remain largely unknown. Additionally, it is unclear whether similar effects arise when abstract choices or physical actions are mimicked. In this study, we used functional near-infrared spectroscopy (fNIRS) to examine the involvement of temporal and parietal brain regions during in-person interactions in which participants were either mimicked by a confederate in terms of their motor movements (<i>n</i>= 30) or their choices (<i>n</i>= 30). In the Choice group, the participant and confederate chose the same (mimicry) or different (no mimicry) paintings in the absence of any physical mirroring action by the confederate. In the Motor group, the participant and confederate performed the same (mimicry) or different (no mimicry) right-hand movements while viewing distinct pairs of pictures. Choice mimicry led to a strong sense of affiliation across various measures, which was evident through activation of the bilateral inferior parietal lobule (IPL). In contrast, motor mimicry produced only a subtle liking effect and showed activation in the left posterior superior temporal sulcus (STS) and the left temporo-parietal junction (TPJ). In addition, awareness of the study's goal increased the right intraparietal sulcus (IPS) activity in the Choice group but did not do so in the Motor group. These findings suggest that choice mimicry exerts a stronger influence on affiliation than motor mimicry and highlight differential neural pathways for detecting mimicked choices and mimicked actions.