There is a name for that: Pluralistic Ignorance

Ever pretended to be entranced by a Portuguese art film that everyone else in the theater seemed to find fascinating? Ever agreed with your dinner companions that a pricey bottle of wine was exquisite, even though it tasted like Windex? You may not have been as alone as you thought. You and everyone else in the room may have just been victims of pluralistic ignorance.

The term, coined in 1931 by psychologists Daniel Katz and Floyd Allport, describes the surprisingly common situation in which individual members of a group privately believe one thing, but think that everyone else in the group believes the opposite. It’s like the real-life version of “The Emperor’s New Clothes,” the fairy tale in which everyone pretends to adore the monarch’s lovely new outfit—until a little boy points out that the emperor isn’t wearing any clothes at all. Katz and Allport came up with the term when their research revealed that students at Syracuse University generally didn’t object to the notion of allowing minorities into then-segregated frat houses and dorms, but were convinced their peers wouldn’t accept such a multicultural move.

College students seem especially susceptible: Turns out many of them are a lot less comfortable with heavy drinking and casual sex than they assume their colleagues to be. Researchers have found similar syndromes at work in everything from vegetarian co-op members’ views of dietary rules to witch hunts in colonial Massachusetts. Similarly, racial segregation in America and communism in the former Soviet Union were both buttressed by people’s exaggerated sense of how many of their fellow citizens supported them. Ignorance is one thing you really don’t want to share.

http://www.psmag.com/culture/pluralistic-ignorance-55562/