EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias

Abstract Group identity induces social cognitive biases, and membership duration may amplify these effects. This study aimed to examine such bias by analysing similarities in neural processing among individuals in competitive scenarios. The fans of two Japanese baseball teams, the Hanshin Tigers and...

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Main Authors: Motoyuki Sanada, Yasushi Naruse
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-08191-z
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author Motoyuki Sanada
Yasushi Naruse
author_facet Motoyuki Sanada
Yasushi Naruse
author_sort Motoyuki Sanada
collection DOAJ
description Abstract Group identity induces social cognitive biases, and membership duration may amplify these effects. This study aimed to examine such bias by analysing similarities in neural processing among individuals in competitive scenarios. The fans of two Japanese baseball teams, the Hanshin Tigers and Orix Buffaloes, watched baseball matches between the teams, and EEG synchronisation was analysed for in-group (same team) and out-group (different team) pairs, considering fan history as a factor representing membership duration. The results revealed that in-group pairs showed stronger centroparietal alpha-phase synchronisation than out-group pairs, suggesting that top-down spatial attention modulated early visual processing in a similar way among in-group members. Furthermore, in-group pairs with longer fan histories exhibited higher parietal alpha power synchronisation, probably reflecting shared engagement and emotional responses, whereas this effect was absent in out-group pairs. Interestingly, longer fan histories were associated with reduced parietal delta and theta phase synchronisations, possibly due to diverse late-stage attentional processes among experienced fans. Additionally, frontal alpha-phase synchronisation increased with fan history, indicating enhanced auditory attention in long-term fans. These findings highlight how group identity and membership duration shape neural processing, and EEG synchronisation analysis provides a robust method for examining biases.
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spelling doaj-art-62e02e711ec44e04ae239ab4618c83d52025-08-20T03:03:40ZengNature PortfolioScientific Reports2045-23222025-07-0115111310.1038/s41598-025-08191-zEEG synchronisation reveals the impact of group identity and membership duration on social cognitive biasMotoyuki Sanada0Yasushi Naruse1Center for Information and Neural Networks, Advanced ICT Research Institute, National Institute of Information and Communications Technology and Osaka UniversityCenter for Information and Neural Networks, Advanced ICT Research Institute, National Institute of Information and Communications Technology and Osaka UniversityAbstract Group identity induces social cognitive biases, and membership duration may amplify these effects. This study aimed to examine such bias by analysing similarities in neural processing among individuals in competitive scenarios. The fans of two Japanese baseball teams, the Hanshin Tigers and Orix Buffaloes, watched baseball matches between the teams, and EEG synchronisation was analysed for in-group (same team) and out-group (different team) pairs, considering fan history as a factor representing membership duration. The results revealed that in-group pairs showed stronger centroparietal alpha-phase synchronisation than out-group pairs, suggesting that top-down spatial attention modulated early visual processing in a similar way among in-group members. Furthermore, in-group pairs with longer fan histories exhibited higher parietal alpha power synchronisation, probably reflecting shared engagement and emotional responses, whereas this effect was absent in out-group pairs. Interestingly, longer fan histories were associated with reduced parietal delta and theta phase synchronisations, possibly due to diverse late-stage attentional processes among experienced fans. Additionally, frontal alpha-phase synchronisation increased with fan history, indicating enhanced auditory attention in long-term fans. These findings highlight how group identity and membership duration shape neural processing, and EEG synchronisation analysis provides a robust method for examining biases.https://doi.org/10.1038/s41598-025-08191-zEEGInter-subject correlationSynchronisationCognitive biasGroup identityMembership duration
spellingShingle Motoyuki Sanada
Yasushi Naruse
EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
Scientific Reports
EEG
Inter-subject correlation
Synchronisation
Cognitive bias
Group identity
Membership duration
title EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
title_full EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
title_fullStr EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
title_full_unstemmed EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
title_short EEG synchronisation reveals the impact of group identity and membership duration on social cognitive bias
title_sort eeg synchronisation reveals the impact of group identity and membership duration on social cognitive bias
topic EEG
Inter-subject correlation
Synchronisation
Cognitive bias
Group identity
Membership duration
url https://doi.org/10.1038/s41598-025-08191-z
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