In psychology, the false-consensus effect or false-consensus bias is a cognitive bias whereby a person tends to overestimate how much other people agree with him or her. There is a tendency for people to assume that their own opinions, beliefs, preferences, values and habits are 'normal' and that others also think the same way that they do. This cognitive bias tends to lead to the perception of a consensus that does not exist, a 'false consensus'. This false consensus is significant because it increases self-esteem. The need to be "normal" and fit in with other people is underlined by a desire to conform and be liked by others in a social environment.
Within the realm of personality psychology, the false-consensus effect does not have significant effects. This is because the false-consensus effect relies heavily on the social environment and how a person interprets this environment. Instead of looking at situational attributions, personality psychology evaluates a person with dispositional attributions, making the false-consensus effect relatively irrelevant in that domain. Therefore, a person's personality potentially could affect the degree that the person relies on false-consensus effect, but not the existence of such a trait.
The false-consensus effect is not necessarily restricted to cases where people believe that their values are shared by the majority. The false-consensus effect is also evidenced when people overestimate the extent of their particular belief is correlated with the belief of others. Thus, fundamentalists do not necessarily believe that the majority of people share their views, but their estimates of the number of people who share their point of view will tend to exceed the actual number.
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.
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. There is no single cause for this cognitive bias; the availability heuristic, self-serving bias and naïve realism have been suggested as at least partial underlying factors.
The false-consensus effect can be contrasted with pluralistic ignorance, an error in which people privately disapprove but publicly support what seems to be the majority view (regarding a norm or belief), when the majority in fact shares their (private) disapproval. While the false consensus effect leads people to wrongly believe that they agree with the majority (when the majority, in fact, openly disagrees with them), the pluralistic ignorance effect leads people to wrongly believe that they disagree with the majority (when the majority, in fact, covertly agrees with them). Pluralistic ignorance might, for example, lead a student to engage in binge drinking because of the mistaken belief that most other students approve of it, while in reality most other students disapprove, but behave in the same way because they share the same mistaken (but collectively self-sustaining) belief. In a parallel example of false consensus, a student who likes binge drinking would believe that a majority also likes it, while in reality, most others dislike it and openly say so.
Major theoretical approaches 
The false-consensus effect can be traced back to two parallel theories of social perception, "the study of how we form impressions of and make inferences about other people". The first is the idea of social comparison. The principal claim of Leon Festinger’s (1954) social comparison theory was that individuals evaluate their thoughts and attitudes based on other people. This may be motivated by a desire for confirmation and the need to feel good about oneself. As an extension of this theory, people may use others as sources of information to define social reality and guide behavior. This is called informational social influence. The problem, though, is that people are often unable to accurately perceive the social norm and the actual attitudes of others. In other words, research has shown that people are surprisingly poor "intuitive psychologists" and that our social judgments are oftentimes inaccurate. This finding helped to lay the groundwork for an understanding of biased processing and inaccurate social perception. The false-consensus effect is just one example of such an inaccuracy.
The second influential theory is projection, the idea that people project their own attitudes and beliefs onto others. This idea of projection is not a new concept. In fact, it can be found in Sigmund Freud’s work on the defense mechanism of projection (1956), D.S. Holmes' work on "attributive projection" (1968), and Gustav Ichheisser’s work on social perception (1970). D.S. Holmes, for example, described social projection as the process by which people "attempt to validate their beliefs by projecting their own characteristics onto other individuals".
Here, a connection can be made between the two stated theories of social comparison and projection. First, as social comparison theory explains, individuals constantly look to peers as a reference group and are motivated to do so in order to seek confirmation for their own attitudes and beliefs. In order to guarantee confirmation and a higher self-esteem, though, an individual might unconsciously project their own beliefs onto the others (the targets of their comparisons). This final outcome is the false-consensus effect. To summarize, the false-consensus effect can be seen as stemming from both social comparison theory and the concept of projection.
The false-consensus effect, as defined by Ross, Greene, and House in 1977, came to be the culmination of the many related theories that preceded it. In their well-known series of four studies, Ross and associates hypothesized and then demonstrated that people tend to overestimate the popularity of their own beliefs and preferences. In each of the studies, subjects or "raters" were asked to choose one of a few mutually-exclusive responses. They would then predict the popularity of each of their choices among other participants, referred to as "actors." To take this a step further, Ross and associates also proposed and tested a related bias in social inferences: they found that raters in an experiment estimated their own response to be not only common, but also not very revealing of the actors' "distinguishing personal dispositions". On the other hand, alternative or opposite responses were perceived as much more revealing of the actors as people. In general, the raters made more "extreme predictions" about the personalities of the actors that did not share the raters' own preference. In fact, the raters may have even thought that there was something wrong with the people expressing the alternative response.
In the ten years after the influential Ross et al. study, close to 50 papers were published with data on the false-consensus effect. Theoretical approaches were also expanded. The theoretical perspectives of this era can be divided into four categories: (a) selective exposure and cognitive availability, (b) salience and focus of attention, (c) logical information processing, and (d) motivational processes. In general, the researchers and designers of these theories believe that there is not a single right answer. Instead, they admit that there is overlap among the theories and that the false-consensus effect is most likely due to a combination of these factors.
Selective exposure and cognitive availability 
This theory is closely tied to the availability heuristic, which suggests that perceptions of similarity (or difference) are affected by how easily those characteristics can be recalled from memory. And as one might expect, similarities between oneself and others are more easily recalled than differences. This is in part because people usually associate with those who are similar to themselves. This selected exposure to similar people may bias or restrict the "sample of information about the true diversity of opinion in the larger social environment". As a result of the selective exposure and availability heuristic, it is natural for the similarities to prevail in one's thoughts.
Botvin, Baker, Dusenbury, and Goldberg (1992) did a popular study on the effects of the FCE among a specific adolescent community in an effort to determine whether students show a higher level of FCE among their direct peers as opposed to society at large. The participants of this experiment were 203 college students ranging in age from 18 to 25 (with an average age of 18.5). The participants were given a questionnaire and asked to answer questions regarding a variety of social topics. For each social topic, they were asked to answer how they felt about the topic and to estimate the percentage of their peers who would agree with them. The results determined that the false-consensus effect was extremely prevalent when participants were describing the rest of their college community; out of twenty topics considered, sixteen of them prominently demonstrated the FCE. The high levels of FCE seen in this study can be attributed to the group studied; because the participants were asked to compare themselves to a group of peers that they are constantly around (and view as very similar to themselves), the levels of FCE increased.
Salience and focus of attention 
This theory suggests that when an individual focuses solely on their own preferred position, they are more likely to fall victim to the false-consensus effect and overestimate its popularity. This is because that position is the only one in their immediate consciousness. Performing an action that promotes the position will make it more salient and may increase the false-consensus effect. If, however, more positions are presented to the individual, the degree of the false-consensus effect might decrease significantly.
Logical information processing 
This theory assumes that active and seemingly rational thinking underlies an individual’s estimates of similarity among others. This is manifested in one’s causal attributions. For instance, if an individual makes an external attribution for their belief, the individual will likely view his or her experience of the thing in question as merely a matter of objective experience. For example, a few movie-goers may falsely assume that the quality of the film is a purely objective entity. To explain their dissatisfaction with it, the viewers may say that it was simply a bad movie (an external attribution). Based on this (perhaps erroneous) assumption of objectivity, it seems rational or "logical" to assume that everyone else will have the same experience; consensus should be high. On the other hand, someone in the same situation who makes an internal attribution (perhaps a film aficionado who is well-aware of his or her especially high standards) will realize the subjectivity of the experience and will be drawn to the opposite conclusion; consensus will be much lower. Though they result in two opposite outcomes, both paths of attribution rely on an initial assumption which then leads to a "logical" conclusion. By this logic, then, it can be said that the false-consensus effect is really a reflection of the fundamental attribution error (specifically the actor-observer bias) in which people prefer situational/external attributions over internal/dispositional ones to justify their own behaviors.
In a study done by Fox, Yinon, and Mayraz, researchers were attempting to determine whether or not the levels of the false-consensus effect changed in different age groups. In order to come to a conclusion, it was necessary for the researchers to split their participants into four different age groups. Two hundred participants were used, and gender was not considered to be a factor. Just as in the previous study mentioned, this study used a questionnaire as its main source of information. The results showed that the FCE was extremely prevalent in all groups, but was the most prevalent in the oldest age group; these participants were labeled as "old-age home residents". They showed the FCE in all 12 areas that they were questioned about. The increase in FCE seen in the oldest age group can be accredited to their high level of "logical" reasoning behind their decisions; the oldest age group has obviously lived the longest, and therefore feels that they can project their beliefs on to all age groups due to their (seemingly objective) past experiences and wisdom . The younger age groups cannot logically relate to those older to them because they have not had that experience and do not pretend to know these "objective" truths. These results demonstrate a tendency for older people to rely more heavily on situational attributions (life experience) as opposed to internal attributions.
Motivational processes 
This theory stresses the benefits of the false-consensus effect: namely, the perception of increased social validation, social support, and self-esteem. It may also be useful to exaggerate similarities in social situations in order to increase liking. It is possible that these benefits serve as positive reinforcement for false-consensus thinking.
||This section is written like a personal reflection or opinion essay rather than an encyclopedic description of the subject. (September 2011)|
The false-consensus effect is an important attribution bias to take into consideration when conducting business and in everyday social interactions. Essentially, people are inclined to believe that the general population agrees with their opinions and judgments, which, true or not, gives them a feeling of more assurance and security in their decisions. This could be an important phenomenon to either exploit or avoid in business dealings. For example, if a man doubted whether he wanted to buy a new tool, breaking down his notion that others agree with his doubt would be an important step in persuading him to purchase it. By convincing the customer that other people in fact do want to buy the appliance, the seller could perhaps make a sale that he would not have made otherwise. In this way, the false-consensus effect is closely related to conformity, the effect in which an individual is influenced to match the beliefs or behaviors of a group. There are two differences between the false-consensus effect and conformity: most importantly, conformity is matching the behaviors, beliefs or attitudes of a real group, while the false-consensus effect is perceiving that others share your behaviors, beliefs or attitudes, whether they really do or not. By making the customer feel like the opinion of others (society) is to buy the appliance, he will feel more confident about his purchase and believe that other people would have made the same decision.
Similarly, any elements of society affected by public opinion—elections, advertising, publicity—are very much influenced by the false-consensus effect. This is partially due to the fact that how people develop their perceptions involves "differential processes of awareness". That is to say, while some people are motivated to reach correct conclusions, others may be motivated to reach preferred conclusions. (It is obvious that the latter category will more often result in a false consensus, because the subject is likely to search actively for like-minded supporters and may discount or ignore the opposition).
There is ambiguity about several facets of the false-consensus effect, as well as its study. First of all, it is unclear exactly which factors play the largest role in the strength and prevalence of the false-consensus effect in individuals (ex: Two individuals in the same group and with very similar social standing could have very different levels of FCE, but it is unclear what social, personality or perceptual differences between them play the largest role in causing this disparity).
Additionally, it can be difficult to obtain accurate survey data about the FCE (as well as other psychological biases) because the search for consistent, reliable groups to be surveyed (often over an extended period of time) often leads to groups that might have dynamics slightly different from those of the "real world." For example, many of the referenced studies in this article examined college students, who might have an especially high level of FCE both because they are surrounded by their peers (and perhaps experience the availability heuristic) and because they often assume they are similar to their peers. This may result in distorted data from some studies of the false-consensus effect.
See also 
- Attributional bias
- Fundamental attribution error
- Illusory superiority
- List of cognitive biases
- Overconfidence effect
- Pluralistic ignorance
- Psychological projection
- The Engineering of Consent
- Manufacturing Consent
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- Aronson, Wilson & Akert 2005, p. 215
- Bauman & Geher 2002, p. 293
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- (Ross et al 1)
- Marks & Miller 1987, p. 72
- Marks & Miller 1987, p. 73
- (Marks 1)
- (Bauman et. al 1)
- Yinon, Yoel; Mayraz, Avigail; Fox, Shaul (1994). "Age and the False-Consensus Effect". The Journal of Social Psychology 134 (6): 717–725. doi:10.1080/00224545.1994.9923006. ISSN 0022-4545.
- Marks & Miller 1987, p. 74
- Nir, L. (2011). "Motivated reasoning and public opinion perception". Public Opinion Quarterly (Oxford University Press). doi:10.1093/poq/nfq076. ISSN 0033-362X.
- Aronson, Elliot; Wilson, Timothy D.; Akert, Robin M. (2005). Social Psychology (7th ed.). Boston: Prentice Hall.
- Bauman, Kathleen P.; Geher, Glenn (2002). "We think you agree: The detrimental impact of the false consensus effect on behavior". Current Psychology 21 (4): 293–318. doi:10.1007/s12144-002-1020-0. ISSN 0737-8262.
- Marks, Gary; Miller, Norman (1987). "Ten years of research on the false-consensus effect: An empirical and theoretical review.". Psychological Bulletin 102 (1): 72–90. doi:10.1037/0033-2909.102.1.72. ISSN 1939-1455.
- Ross, L (1977). "The false consensus effect: An egocentric bias in social perception and attribution processes". Journal of Experimental Social Psychology 13 (3): 279–301. doi:10.1016/0022-1031(77)90049-X. ISSN 00221031.
Further reading 
- Kunda, Ziva (1999), Social Cognition: Making Sense of People, MIT Press, pp. 396–401, ISBN 978-0-262-61143-5, OCLC 40618974
- Fields, James M.; Schuman, Howard (1976). "Public Beliefs About the Beliefs of the Public". Public Opinion Quarterly 40 (4): 427. doi:10.1086/268330. ISSN 0033362X.