False consensus bias: What the minority think…

social norms

In fact, many do not; we overestimate in most instances – sometimes, grossly. We falsely – rather erroneously – believe that many are in consensus with us with our judgments, and those who are not in consensus with us are not only a few in number but “deviant” also; this phenomenon was termed the “false consensus effect” in 1976 by Lee Ross, Greene, and House from the Stanford University.

Ross et al. study series: 1976

Ross and his team asked a group of students to choose one out of two options to choose for a series of hypothetical situations, predict the percentage of students who would and wouldn’t choose their favored option, and their opinion about the personal characteristics of the students who would and wouldn’t choose their option.

“Eat at Joe’s”

Of the four scenarios they studied, I briefly describe here the hypothetical “eat at Joe’s” study. They sought students’ willingness to walk 30 minutes around the campus wearing a signboard displaying “eat at Joe’s”. Then students were required to respond to the following questions:

  • What % of your peers would do that?
  • What % of them would refuse that?
  • their choice?

The results were as follows:

  • 53% of the students who chose to wear the signboard thought 64.6% of their peers would do that same.
  • the rest – 47% – students who chose not to wear the signboard thought 68.8% of their peers would do that same.

As we can see that the students overestimated their peers’ opinions in favor of their chosen options than was the case.

Moreover, the students perceived the alternate opinions as ” uncommon, deviant, or inappropriate”!

Does this resonate with you?

This is a cognitive trap into which we all fall.

A meta-analysis on false consensus bias: 1985

A decade after the Lee Ross et al., study – in 1985, Brian Mullen and his team meta-analyzed as many as 115 studies that tested this bias. These studies covered a range of topics: smoking, food choices, sports, politics, etc. The combined effects of all the studies became “highly significant and its effect sizes were of moderate magnitude”.

False consensus among heavy drinkers:1986

In 1986, Wesley Perkins and Alan Berkowitz analyzed data that reflected attitudes about drinking from a representative sample of 1,116 college students in the New York state. The data also included responses to a series of survey questions about drinking behavior. The students had to choose one out of five statements that best represented their own attitude as well as their perception of their peers’ attitude.

Of those five, two statements were as follows:

  • “A frequent “drunk” is okay if that’s what the individual wants to do”.
  • “An occasional “drunk” is okay even if it interferes occasionally with grades and responsibilities.

The above statements reflect very permissive (liberal) attitudes.

What do you think about their response?

Only 9.5% and 9.3% chose these two statements as their personal attitudes – altogether 18.8%; however, 29.5% and 33.2% perceived these statements as their peers’ attitudes respectively – altogether 62.7% of the total students responded!

They grossly overestimated – those who were, in fact, the minority perceived themselves as falsely in consensus with the majority – that the majority of their peers were with them.

This is how it happens; reasoning justifies themselves to continue their unhealthy drinking pattern. In this study, the researchers found that not only the group with liberal attitudes towards drinking demonstrated false consensus, they also reported more drinking levels than those with restrictive attitudes.

In fact, this was not the only study; a series of studies at different universities demonstrated the prevalence of this bias.

The false consensus among adolescent Smokers: 2009

In 2009, Otten et al. demonstrated this bias among Dutch adolescents. In addition to their own smoking behavior, these adolescents estimated the proportions of their friends who smoked on a 5-point scale. The scale was as follows:

  • 1= none of my friends smoke
  • 2= less than 50% of my friends smoke
  • 3=50% of my friends smoke
  • 4= more than 50% of my friends smoke
  • 5= all of my friends smoke

They found that regular smokers overestimated the prevalence of smoking of their friends significantly higher than friends of nonsmokers’ smoking.

Self-fulfilling Prophecy

What may happen next? The false consensus bias may lead to the “self-fulfilling prophecy” with time; the minority becoming the real majority due to the influence of the false consensus bias.


Even those who do not hold the same attitudes may spread it like carriers spreading an infectious disease.

Author: Prasantha De Silva

A specialist in Community Medicine board-certified in Sri Lanka and a research analyst in Canada

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