illusion of transparency

You act as if you know what others are thinking.

A 1998 study demonstrated that people consistently believe they are more transparent to others than they actually are.

Gilovich, Savitsky, and Medvec, 1998, Journal of Personality and Social Psychology

You are far more mysterious to others than you perceive yourself to be.

Where this comes from

Study: Gilovich et al., 2002, Journal of Personality and Social Psychology
What the check found: The phenomenon of the 'illusion of transparency' is well-documented in psychological research, but the cited paper was published in 1998, not 2002.
Confidence: Solid, with limits

One of these every day, and every one names the study it came from. When a finding is contested, it says so.