Study Identifies 40 Brain Regions Predicting Future Friendships Based on Pre-Existing Neural Similarity

A groundbreaking study published in Nature Human Behaviour suggests that pre-existing similarities in brain responses can predict the formation of friendships, potentially outweighing factors like shared interests or environment. "Fascinating paper on if neural similarity/brain responses may be a better predictor of friendships vs interests, environment, physical proximity," stated Sally Shin in a recent tweet, drawing attention to this significant research. The findings, from researchers at UCLA and Dartmouth College, tracked new graduate students over eight months to observe emerging social bonds.

The research involved 41 incoming graduate students whose brains were scanned using fMRI while they watched various movie clips. This initial scan, conducted before participants had significant interaction, aimed to capture their baseline neural responses. Over the subsequent eight months, the students' social networks were meticulously mapped, allowing researchers to observe and analyze the development of their friendships.

The study found that individuals who later became friends exhibited significantly higher pre-existing neural similarity in specific brain regions. Notably, the left orbitofrontal cortex (OFC), a region associated with processing subjective value and preferences, showed this predictive similarity for close friends compared to those more socially distant. This suggests that shared tastes and appealing qualities might be rooted in similar neural processing.

Furthermore, the research revealed that dyads who grew closer over time displayed greater pre-existing neural similarity across 40 cortical regions. These included areas within the default mode network (DMN), involved in social cognition and sense-making, the frontoparietal control network (FPCN), crucial for executive control and integrating information, and the dorsal attention network, linked to attentional allocation. This broad neural alignment indicates that how individuals interpret, attend to, and emotionally respond to their surroundings are precursors to future social closeness.

This longitudinal study provides compelling evidence for "neural homophily," demonstrating that brain-based compatibility can predict who will form friendships. Unlike previous cross-sectional studies, this research establishes that neural similarity precedes friendship formation, offering new insights into the biological underpinnings of human social connections. The findings underscore the importance of deep interpersonal compatibilities, reflected in shared brain responses, in shaping our social networks.