Normativity vs. uniqueness: effects of social relationship strength on neural representations of others

Abstract

Understanding others involves inferring traits and intentions, a process complicated by our reliance on stereotypes and generalized information when we lack personal information. Yet, as relationships are formed, we shift toward nuanced and individualized perceptions of others. This study addresses how relationship strength influences the creation of unique or normative representations of others in key regions known to be involved in social cognition. Employing a round-robin interpersonal perception paradigm (N = 111, 20 groups of five to six people), we used functional magnetic resonance imaging to examine whether the strength of social relationships modulated the degree to which multivoxel patterns of activity that represented a specific other were similar to a normative average of all others in the study. Behaviorally, stronger social relationships were associated with more normative trait endorsements. Neural findings reveal that closer relationships lead to more unique representations in the medial prefrontal cortex and anterior insula, areas associated with mentalizing and person perception. Conversely, more generalized representations emerge in posterior regions like the posterior cingulate cortex, indicating a complex interplay between individuated and generalized processing of social information in the brain. These findings suggest that cortical regions typically associated with social cognition may compute different kinds of information when representing the distinctiveness of others.

Keywords: individuation; normative; person perception; social cognition; social relationship.

Figure 1.

fMRI analysis was performed by acquiring brain activity estimates for each group member, segmenting them into 400 regions, creating a normative average pattern for each region excluding the specific representation being compared, and calculating Spearman’s rank correlation distance between the specific representation and normative average to measure dissimilarity, which was then predicted by the strength of the social relationship between the subject and each group member.

Figure 2.

Variability in social relationship strength across 20 different groups. The ridgeline plot illustrates the distribution of perceived relationship strength within each group, highlighting both within-group variability and between-group differences. Groups exhibit a range of relationship strengths, with some groups reporting stronger ties and others weaker connections. Groups were deliberately recruited to enhance variability, including friend groups, academic peers, and work acquaintances, to capture a wide spectrum of familiarity.

Figure 3.

Brain regions exhibiting significant relationships with social relationship strength, where warm colors indicate areas in which stronger social ties predict greater uniqueness in neural representations of group members compared to the normative average, while cool colors mark regions where stronger social relationships correspond to more generalized neural patterns aligning with the normative group average.