Inter-brain synchronization is weakened by the introduction of external punishment.

"data availability the datasets generated during the current study are available in mendeley data. data availability the datasets generated during the current study are available in mendeley data"

"Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest."

"Funding This work was supported by the National Social Science Foundation of China (Grant number: 20AZD044), National National Science Foundation of China (Grant Number: 71673152, 71942002), Major Research Project of Humanities and Social Scineces of Shandong University (NO. 21RWZD15), the Natural Science Fund of Shandong Province (Grant numbers: ZR201910300146) and Social Science Found of Shandong Province (Grant numbers: 21DGLJ09)."