8/ Special thanks to all the co-authors who made this work possible!

7/ Replication studies are needed to confirm these findings, and without overinterpreting the results, we hope this study contributes to a broader rethinking of heart rate variability as a psychophysiological index.

6/ These findings may suggest that HRV–psychological associations are not necessarily universally consistent, but are instead influenced by a range of nuanced cultural, environmental, developmental, and methodological factors.

5/ We also conducted equivalence testing, which showed that any observed effects were small and practically negligible.

4/ We found no significant associations between HRV and any of the psychological outcomes we measured (except for a small, unexpected effect on externalizing behavior).

3/ We tested these pre-registered hypotheses in a large, diverse sample of 1,107 adolescents living in urban poverty across Colombia, Nepal, and South Africa.

2/ Some studies have shown that resting heart rate variability (HRV) may correlate with psychological outcomes, such as self-regulation and psychopathology.