What is the "illusion of competence" (illusion of fluency)?

The mistake of treating ease of processing as evidence of knowing — smooth, familiar-feeling material feels learned even when it isn't.

When text reads easily and the words feel familiar, your brain registers that fluency and quietly converts it into confidence. But familiarity is not the same as retrievability. Recognizing a passage when you see it says nothing about whether you could produce the idea with the book closed.

Re-reading and highlighting are the classic culprits: they crank up fluency while building little durable memory, so they inflate confidence far more than competence. The feeling of knowing and actual knowing come apart — and the feeling is the louder of the two.