A self without a "we": Individuals with Borderline personality disorder show signatures of disrupted social basis functions

Abstract

A capacity to navigate social relationships is fundamental to human wellbeing. However, the cognitive mechanisms underlying social dysfunction in psychiatric conditions remain poorly understood. Using an abstract multi-person decision making task that isolates the relational structure of multi-person interactions, we compare non-clinical controls (NCC, n=51) and individuals with BPD symptoms (n=46), a condition characterized by disturbances in self-other boundaries and chronic feelings of loneliness. Generally, we found a pattern of less self-centered decision-making in BPD. More specifically, individuals with BPD showed signatures of perceiving opponents as a coherent group ("them"), but a markedly reduced tendency to represent themselves as part of their own team ("us"). This pattern of results points towards a disruption of a primary social basis function. Our laboratory findings extend to experienced loneliness in daily life as measured by ecological momentary assessments (EMA). Together, this suggests that BPD is characterized by an unbalanced representation of social structure, with an attenuated "we" alongside a heightened "they".