Spotlight Effect

Overestimation of how much other people notice one's appearance and blunders, shown with an embarrassing t-shirt.

Specifications & Metrics

Wearers of a Barry Manilow t-shirt guessed about half of onlookers would notice it; roughly a quarter actually did.
The effect extends to miscalled words in discussion and to the visibility of one's nervousness.
It is anchored in egocentrism: people cannot fully discount their own salient experience of the situation.