False consensus effect

In <a href="/facts/Psychology/duoqW7Sz">psychology</a>, the false consensus effect, also known as consensus bias, is a pervasive <a href="/facts/Cognitive_bias/49YKVhmN">cognitive bias</a> that causes people to overestimate the extent to which other people share their beliefs and views; it is the tendency to "see their own behavioral choices and judgments as relatively common and appropriate to existing circumstances". In other words, they assume that their personal qualities, characteristics, beliefs, and actions are relatively widespread through the general population.
This false consensus is significant because it increases <a href="/facts/Self-esteem/vaMskKL0">self-esteem</a> (<a href="/facts/Overconfidence_effect/kkx08atR">overconfidence effect</a>). This bias is especially prevalent in group settings where one thinks the collective opinion of their own group matches that of the larger population. Since the members of a group reach a consensus and rarely encounter those who dispute it, they tend to believe that everybody thinks the same way. The false-consensus effect is not restricted to cases where people believe that their values are shared by the majority, but it still manifests as an overestimate of the extent of their belief. Additionally, when confronted with evidence that a consensus does not exist, people often assume that those who do not agree with them are defective in some way. 
The false consensus effect has been widely observed and supported by empirical evidence. One recent study has shown that consensus bias may improve decisions about other people's preferences. Ross, Green and House first defined the false consensus effect in 1977 with emphasis on the relative commonness that people perceive about their own responses; however, similar projection phenomena had already caught attention in psychology. Specifically, concerns with respect to connections between individual's personal predispositions and their estimates of peers appeared in the literature for a while. For instances, Katz and Allport in 1931 illustrated that students’ estimates of the amount of others on the frequency of cheating was positively correlated to their own behavior. Later, around 1970, same phenomena were found on political beliefs and <a href="/facts/Prisoner%2527s_dilemma/44kueSBQ">prisoner's dilemma</a> situation. In 2017, researchers identified a persistent egocentric bias when participants learned about other people's snack-food preferences. Moreover, recent studies suggest that the false consensus effect can also affect professional decision makers; specifically, it has been shown that even experienced marketing managers project their personal product preferences onto consumers.

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False consensus effect