## 3 Results
### Analysis of Pairwise HRV Synchronization between Group Members  
In order to assess the pairwise heart rhythm synchronization among participants within each group before, during and after the Heart Lock-in period, we employed a similar chaotic attractor embedding technique which is described in [24]. Using this technique, an approximately 300 data point long series of each participant's HRV was used for each optimal time lag value. Each period was 15-min long, which corresponded to 1800 data points. After the application of this algorithm on each participant's HRV data, we obtained six optimal time lag values for each 15-min period, before, during and after the HLI. The sequences of optimal time lag values for all participants from each group, for each time period, were analyzed separately. In order to assess the pairwise heart rhythm synchronization between participants', we computed the Euclidean distance of the optimal time lag vectors of each participant to all other participants in their group and calculated the average distance for all participants. The lower the mean Euclidean distances, the higher the level of pairwise synchronization. Figures, corresponding to individual HRV pairwise synchronization results for each of the groups before, during and after the Heart Lock-In (HLI) are displayed in Appendix B. The results of a repeated measures ANOVA test of within-subjects effects are shown in Figure 5 and Table 10. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multirow{2}{*}{\(N\)} & \multirow{2}{*}{**Mean**} & \multirow{2}{*}{\begin{tabular}{c} **Lower** \\ **95\% CI** \\ \end{tabular} } & \multirow{2}{*}{**\
\begin{tabular}{c} **Upper** \\ **95\% CI** \\ \end{tabular}} & \multirow{2}{*}{**df**} & \multirow{2}{*}{
\begin{tabular}{c} **Mean** \\ **Square** \\ \end{tabular} } & \multirow{2}{*}{**F**} & \multirow{2}{*}{\(p<\)} & \multirow{2}{*}{\(p<\)} & \multirow{2}{*}{\(p<\)} & \multirow{2}{*}{\(p<\)} \\  & & & & & & & & & & 1 **vs. 2** & 1 **vs. 3** & 2 **vs. 3** \\ \hline UK & 1 Before & 9 & 1.65 & 1.38 & 1.92 & 1.05 \({}^{\text{a}}\) & 7.49 & 4.34 & ns & 0.35 & - & - & - \\  & 2 During & 9 & 2.67 & 1.37 & 3.96 & & & & & & & & \\  & 3 After & 9 & 1.43 & 1.26 & 1.60 & & & & & & & & \\ \hline LT & 1 Before & 19 & 1.30 & 1.17 & 1.42 & 1.196 \({}^{\text{a}}\) & 2.23 & 6.65 & 0.05 & 0.27 & ns & ns & 0.05 \\  & 2 During & 19 & 1.70 & 1.38 & 2.03 & & & & & & & & \\  & 3 After & 19 & 1.21 & 1.10 & 1.32 & & & & & & & & \\ \hline NZ & 1 Before & 19 & 1.33 & 1.18 & 1.48 & 1.389 \({}^{\text{a}}\) & 4.25 & 13.30 & 0.001 & 0.43 & 0.01 & ns & 0.01 \\  & 2 During & 19 & 2.05 & 1.65 & 2.45 & & & & & & & & \\  & 3 After & 19 & 1.42 & 1.21 & 1.63 & & & & & & & & \\ \hline SA & 1 Before & 11 & 1.27 & 1.10 & 1.45 & 1.097 \({}^{\text{a}}\) & 3.02 & 4.32 & ns & 0.30 & - & - & - \\  & 2 During & 11 & 1.97 & 1.27 & 2.67 & & & & & & & & \\  & 3 After & 11 & 1.32 & 1.12 & 1.53 & & & & & & & & \\ \hline CA & 1 Before & 11 & 1.40 & 1.05 & 1.76 & 1.086 \({}^{\text{a}}\) & 18.85 & 21.52 & 0.001 & 0.68 & 0.01 & ns & 0.01 \\  & 2 During & 11 & 3.09 & 2.21 & 3.96 & & & & & & & & \\  & 3 After & 11 & 1.43 & 1.21 & 1.65 & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The results of a repeated measures (within-subjects) ANOVA test assessing differences in the coherence score for all five groups during 15-min periods before (1), during (2) and after (3) using the Heart lock-In technique (\({}^{\text{a}}\)—[PERSON]’s Test of Sphericity was violated, Greenhouse-Geisser df correction applied; \({}^{\text{b}}\)—Adjustment for multiple comparisons: Bonferroni). Note that a coherence score below one is considered as low coherence, scores between one and two as medium, and scores above two as high levels of coherence. It can be seen, for example, that California’s and New Zealand’s group members’ HRV coherence was significantly higher during the HLI period than before and after the HLI period, etc.