English: A movie showing MEG hyperscanning during an interactive task. In this experimental paradigm, the subjects were a mother and her child. Short movies and another's facial expression were alternately displayed at least for 10 and 15 s, respectively, on the half-mirror screen in front of them (as indicated in the left movies) while simultaneous neuromagnetic recording of their brain activities are performed (as indicated on the right waveforms). The lowest signals in the waveforms were the trigger signals not only to detect the change of visual stimuli but also to measure the time delay of facial expression movies. In the facial expression periods, a mother and her child looked at each other's facial expression. In the short movie periods, a mother and her child looked at the same short movies that were selected according to the child's interest. The subject's faces were obscured in this supplementary movie to protect personal information. Four infrared circular markers (as indicated as white circular dots on the child's face on the movie) were attached on the child's face to correct the child's motion. Note that the child keeps still while looking at his mother's face.