In social psychology, pluralistic ignorance, a term coined by Daniel Katz and Floyd H. Allport in 1931,[1] describes "a situation where a majority of group members privately reject a norm, but assume (incorrectly) that most others accept it...It is, in Krech and Crutchfield’s (1948, pp. 388–89) words, the situation where 'no one believes, but everyone thinks that everyone believes.'".[2] This, in turn, provides support for a norm that may be, in fact, disliked by most people.
Pluralistic ignorance can be contrasted with the false consensus effect. In pluralistic ignorance, people privately disdain but publicly support a norm (or a belief), while the false consensus effect causes people to wrongly assume that most people think like them, while in reality most people do not think like them (and express the disagreement openly). For instance, pluralistic ignorance may lead a student to drink alcohol excessively because she believes that everyone else does that, while in reality everyone else also wish they could avoid binge drinking, but no one expresses that due to the fear of being ostracized. A false consensus for the same situation would mean that the student believes that most other people do not enjoy excessive drinking, while in fact most other people do enjoy that and openly express their opinion about it.
Pluralistic ignorance was blamed for a perception (among American whites) that grossly exaggerated the support of other American whites for segregation in the 1960s.[3] It has also been named a reason for the illusionary popular support that kept the communist regime in the Soviet Union, as many opposed the regime but assumed that others were supporters of it. Thus, most people were afraid to voice their opposition.[4] Witch hunts in the past and during the Cold War (as recently as the 1950s) and assaults on homosexuals could be other cases of pluralistic ignorance.[2]
In a series of studies conducted to test the effect of pluralistic ignorance, Prentice and Miller [5] studied the consequences of pluralistic ignorance at Princeton University. They found that, on average, private levels of comfort with drinking practices on campus were much lower than the perceived average. In the case of men, they found a shifting of private attitudes toward this perceived norm, a form of cognitive dissonance. Women, on the other hand, were found to have an increased sense of alienation on the campus but lacked the attitude change detected in men, presumably because norms related to alcohol consumption on campus are much more central for men than for women. Research has shown that pluralistic ignorance plagues not only those who indulge, but also those who abstain: from gambling, smoking, and drinking[6] and among some who follow vegetarianism.[7] The latter has found that Pluralistic Ignorance can be caused by the structure of the underlying social network, not cognitive dissonance.
Pluralistic ignorance may partially explain the bystander effect: the observation that people are more likely to intervene in an emergency situation when alone than when other persons are present.[8] If people monitor the reactions of others in such a situation, they may conclude from the inaction of others that other people think that it is not necessary to intervene. Thus no one may take any action, even though some people privately think that they should do something. On the other hand, if one person intervenes, others are more likely to follow and give assistance.