  Loneliness is detrimental to well-being and is often accompanied by
self-reported feelings of not being understood by others. What contributes to
such feelings in lonely people? We used functional magnetic resonance imaging
(fMRI) of 66 participants to unobtrusively measure the relative alignment of
people's mental processing of naturalistic stimuli and tested whether or not
lonely people actually process the world in idiosyncratic ways. We found
evidence for such idiosyncrasy: lonely individuals' neural responses were
dissimilar to their peers, particularly in regions of the default-mode network
in which similar responses have been associated with shared perspectives and
subjective understanding. These relationships persisted when controlling for
demographic similarities, objective social isolation, and participants'
friendships with each other. Our findings suggest the possibility that being
surrounded by people who see the world differently from oneself, even if one is
friends with them, may be a risk factor for loneliness.
