Figure 5.

Rapid emergence of interpersonal synchrony of spontaneous movements

We cross-correlated participants’ movement velocity time series (separately for each body part combination) to estimate the lag at which the highest coefficient (i.e., the peak) occurred. The lags associated with the highest coefficients were notably close to lag “0”, implying that IMS emerged very quickly, and this was so across all body part combinations. Each colored line represents correlation coefficients—with ±10 s time lags—averaged across Vision trials and conditions. The vertical black line represents the lag “0” and its height is proportional to the y axis (indexing the correlation coefficient). The distribution of the time lags associated with the peaking coefficients is shown in the inset (all body part combinations are pooled here). For a comparison, the distribution associated with the No Vision conditions is also shown. Note that the peaks associated with the Vision conditions have remarkably shorter lag compared to those associated with the No Vision conditions (Wilcoxon signed rank test Z = 6.23, p < 0.001).