Lonely individuals process the world in idiosyncratic ways

Loneliness (i.e., the distressing feeling that often accompanies the subjective sense of social disconnection) is detrimental to mental and physical health, and deficits in self-reported feelings of being understood by others is a risk factor for loneliness. What contributes to these deficits in lonely people? We used functional magnetic resonance imaging (fMRI) to unobtrusively measure the relative alignment of various aspects of people's mental processing of naturalistic stimuli (specifically, videos) as they unfold over time. We thereby tested whether lonely people actually process the world in idiosyncratic ways, rather than only exaggerating or misperceiving how dissimilar others' views are to their own (which could lead them to feel misunderstood, even if they actually see the world similarly to those around them). We found evidence for such idiosyncrasy: lonely individuals' neural responses during free viewing of the videos were dissimilar to peers in their communities, particularly in brain regions (e.g., regions of the default-mode network) in which similar responses have been associated with shared psychological perspectives and subjective understanding. Our findings were robust even after controlling for demographic similarities, participants' overall levels of objective social isolation, and their friendships with each other. These results suggest that being surrounded predominantly by people who see the world differently from oneself may be a risk factor for loneliness, even if one is friends with them.