Brain synchrony between interacting sibling pairs during real-time cooperation: an fMRI hyperscanning study
Abstract
Siblings typically represent the longest-lasting social relationships. Second-person neuroscience provides a framework for studying the neural mechanisms of real-time, reciprocal social interactions. Yet, most studies have focused on simplified coordination tasks, limited brain regions, and did not investigate neural dynamics between siblings. In the first study investigating brain synchrony between siblings to date, we used fMRI hyperscanning to simultaneously record brain activity in 50 same-sex healthy young adult sibling pairs while they played a complex collaborative problem-solving Tetris game requiring continuous non-verbal complementary coordination. Brain synchrony was quantified using inter-subject correlation across 36 regions of interest (ROIs) of the social brain atlas.
The interacting sibling pairs showed significantly higher brain synchrony than randomly permuted non-sibling pairs in 19 ROIs (FDR-corrected p < .05). These regions were primarily located within the higher-level theory of mind subnetwork (including bilateral temporo-parietal junction, precuneus and dorsomedial prefrontal cortex), and intermediate-level subnetwork (including anterior insula, inferior frontal gyrus). Greater synchrony in the left temporo-parietal junction significantly predicted better cooperative performance, suggesting that shared neural modelling of a partner's intentions supports effective collaboration. Synchrony in frontal and temporal regions was weakly modulated by cooperative and competitive sibling relationship characteristics; however, these effects did not survive correction for multiple comparisons and should be interpreted cautiously (uncorr. p < .05).
This study provides first evidence that real-time cooperation between siblings is supported by inter-brain synchrony in core social brain networks. We highlight the value of ecologically valid hyperscanning approaches for investigating neural mechanisms of cooperation in long-term relationships, advancing the field of relational neuroscience.
Related
- fMRI hyperscanning reveals widespread neural coupling during natural conversations
- A Dynamic State‐Based Framework for Quantifying Triadic Autonomic Synchrony During Group Decision‐Making
- Loss contexts enhance dorsolateral prefrontal interpersonal neural synchrony during successful human deceptive recommendations
- Brain-to-brain synchrony during shared reminiscing predicts connection and memory in romantic couples
- Interpersonal Synchrony During a Client-Therapist Role-Play Interaction: The Role of Modalities, Facets, and Relational Context.
BibTeX
@misc{hernandezpena2026brain,
title = {{Brain synchrony between interacting sibling pairs during real-time cooperation: an fMRI hyperscanning study}},
author = {Lucia Hernandez-Pena and Arezoo Taebi and Julia Koch and Klaus Mathiak and Lisa Wagels},
howpublished = {PsyArXiv},
year = {2026},
month = oct,
doi = {10.31234/osf.io/kjc5s_v1},
url = {https://osf.io/preprints/psyarxiv/kjc5s_v1/},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Brain synchrony between interacting sibling pairs during real-time cooperation: an fMRI hyperscanning study
AU - Lucia Hernandez-Pena
AU - Arezoo Taebi
AU - Julia Koch
AU - Klaus Mathiak
AU - Lisa Wagels
PY - 2026
DA - 2026/10/25
PB - PsyArXiv
DO - 10.31234/osf.io/kjc5s_v1
UR - https://osf.io/preprints/psyarxiv/kjc5s_v1/
AB - Siblings typically represent the longest-lasting social relationships. Second-person neuroscience provides a framework for studying the neural mechanisms of real-time, reciprocal social interactions. Yet, most studies have focused on simplified coordination tasks, limited brain regions, and did not investigate neural dynamics between siblings. In the first study investigating brain synchrony between siblings to date, we used fMRI hyperscanning to simultaneously record brain activity in 50 same-sex healthy young adult sibling pairs while they played a complex collaborative problem-solving Tetris game requiring continuous non-verbal complementary coordination. Brain synchrony was quantified using inter-subject correlation across 36 regions of interest (ROIs) of the social brain atlas. The interacting sibling pairs showed significantly higher brain synchrony than randomly permuted non-sibling pairs in 19 ROIs (FDR-corrected p < .05). These regions were primarily located within the higher-level theory of mind subnetwork (including bilateral temporo-parietal junction, precuneus and dorsomedial prefrontal cortex), and intermediate-level subnetwork (including anterior insula, inferior frontal gyrus). Greater synchrony in the left temporo-parietal junction significantly predicted better cooperative performance, suggesting that shared neural modelling of a partner's intentions supports effective collaboration. Synchrony in frontal and temporal regions was weakly modulated by cooperative and competitive sibling relationship characteristics; however, these effects did not survive correction for multiple comparisons and should be interpreted cautiously (uncorr. p < .05). This study provides first evidence that real-time cooperation between siblings is supported by inter-brain synchrony in core social brain networks. We highlight the value of ecologically valid hyperscanning approaches for investigating neural mechanisms of cooperation in long-term relationships, advancing the field of relational neuroscience.
ER -