People think about their own mental states with more detail than the mental states of other people

Across 4 studies - 2 fMRI and 2 behavioral – the study finds that people think that their own mental states are highly differentiated from each other, but think about the states of another person as relatively similar to each other (intra-personally).

In other words, you may differentiate between your own feelings of "joy," "ecstasy," and "contentment," but be more likely to lump all of these states under the common umbrella of "happiness" when thinking about someone else's mind.

This trend holds regardless of whether the other person is a socially close other, like a friend or family member, or a socially distant other. However, the states of a close other are somewhat more differentiated from each other than are the states of a distant other. In the brain, we find these effects concentrated in regions previously implicated in mental state representation, most prominently medial prefrontal cortex, medial parietal cortex, and the temporoparietal junction.

Together these results suggest that we think about our own minds with greater granularity than the minds of other people. This may be because we have privileged access to our own minds, extensive experience with ourselves, or just greater motivation to understand the self. This effect may also help explain why we often use our own mind as a model for the minds of others: by tapping into high-fidelity representations of our own states, we may form better social inferences about others, albeit potentially at the cost of some degree of egocentricity.

Read the full article from Nature Communications: “People represent their own mental states more distinctly than those of others”