Barnum effect
Etymology
Named by psychologist Paul Meehl in 1956 after showman P. T. Barnum, associated with the line "a little something for everybody." It is also called the Forer effect, after Bertram Forer’s 1948 demonstration in which students rated a generic profile — handed to all of them identically — as a near-perfect fit for themselves.
noun · /BAR-num ih-FEKT/
The tendency to accept vague, general personality descriptions as uncannily accurate about you specifically.
What it names
Why horoscopes and personality quizzes feel personal — a statement true of almost everyone reads as a portrait of you.
Example
The personality report was pure Barnum effect: "You have great potential you haven’t fully tapped" fits literally anyone.
Related idea
Confirmation bias keeps it running — you notice the lines that fit and quietly skip the ones that don’t.