In plain language
Humans are deeply social — but are there biological traits that make some people quicker to bond with a new group? This study looked at cardiac vagal tone, measured as high-frequency heart rate variability (HF-HRV): the natural beat-to-beat variation in heart rate produced by the parasympathetic nervous system via the vagus nerve. Higher resting HF-HRV has previously been linked to better emotion regulation, positive emotions, and social connectedness.
Ninety-one adults had resting heart recordings taken before and after a laboratory session. They then took part in a classic minimal group paradigm: they imagined being randomly assigned to an arbitrary "Blue group" (versus a "Red group"), allocated money to anonymous members of both groups, and rated their feelings towards each group. People with higher HF-HRV showed more ingroup favouritism in the money allocations — mainly because they gave more to their own group, not because they gave less to the other group — and reported stronger feelings of affiliation with their new ingroup, while feelings towards the outgroup were unaffected.
These effects survived controls for age, gender, BMI, mood, caffeine, smoking, alcohol, time of day, and respiration rate, and held whether or not participants had first been primed with caring-related words through a brief loving-kindness exercise. The study is the first to connect decades of research on ingroup favouritism with the newer literature on cardiac vagal tone, suggesting a calm, flexible nervous system makes it easier to affiliate with novel groups.
Key findings
- Higher resting HF-HRV was associated with greater ingroup favouritism when allocating money in a minimal group paradigm (e.g., zero-order r = .29 for mean HF-HRV).
- The effect was driven mostly by allocating more money to the ingroup, not by taking money away from the outgroup — genuine ingroup favouritism rather than outgroup derogation.
- HF-HRV was also positively associated with self-reported feelings of affiliation towards the new ingroup, but unrelated to feelings towards the outgroup.
- Effects remained substantial after controlling for age, gender, BMI, mood, caffeine consumption, time of day, smoking, alcohol use, and respiration rate, and were confirmed by 10-fold cross-validation.
- A brief caring (loving-kindness) priming manipulation did not shift ingroup favouritism: participants favoured their ingroup regardless of priming condition.
- Participants overall allocated more money to their imagined ingroup than the outgroup (mean difference 9.83), replicating the classic minimal group effect without using deception.
How to cite
APA
Sahdra, B. K., Ciarrochi, J., & Parker, P. D. (2015). High-frequency heart rate variability linked to affiliation with a new group. PLoS ONE, 10(6), e0129583. https://doi.org/10.1371/journal.pone.0129583
BibTeX
@article{sahdra2015high,
title = {High-Frequency Heart Rate Variability Linked to Affiliation with a New Group},
author = {Sahdra, Baljinder K. and Ciarrochi, Joseph and Parker, Philip D.},
journal = {PLoS ONE},
volume = {10},
number = {6},
pages = {e0129583},
year = {2015},
doi = {10.1371/journal.pone.0129583}
}
Related work
- All publications by Joseph Ciarrochi (searchable, with free PDFs)
- Process-Based Therapy & Idionomic Analysis
Author: Joseph Ciarrochi (ORCID 0000-0003-0471-8100). Free copy hosted with permission for scholarly use. Please cite the published version via the DOI above.