Social brain fingerprinting: unique functional connectomes underpin interpersonal behaviours in non-autistic and autistic adults
Human social interaction requires continuous adaptation while preserving stable individual patterns of brain organisation. This study examined whether functional connectome fingerprinting captures person-specific organisation during reciprocal interaction and whether its spatial architecture relates to social role and autistic traits. fMRI data from 70 adults forming 35 dyads were analysed during an iterated Ultimatum Game: 19 non-autistic Proposer-non-autistic Responder dyads and 16 non-autistic Proposer-autistic Responder dyads. Functional connectivity across 400 cortical parcels was used to assess whole-brain identifiability and edge-wise reliability. Connectomes remained identifiable across datasets, roles, and task conditions, with no reduction in global identifiability in mixed dyads. Edge-wise analyses revealed role-related and dataset-dependent differences across distributed large-scale networks. Role-sensitive connectivity features were associated with Autism-Spectrum Quotient scores, supported out-of-sample prediction, and topology-derived features classified AQ-threshold status above chance. Stable connectomic signatures therefore persist during reciprocal interaction while their network organisation varies with social role and autistic traits.