With bombastic fireworks, waving flags, and tables piled high with barbecued meat, American exceptionalism was on fervent display yesterday. But the majority of Americans don't just believe their country is exceptional; they believe they are, too. A survey of Americans published to PLoS ONE found that nearly two-thirds of respondents believe they are smarter than average.

Researchers made use of a nationwide SurveyUSA telephone poll conducted in 2009 along with a survey conducted via Amazon Mechanical Turk in 2011. In all, more than 2,800 respondents were asked to answer "Strongly Agree," "Mostly Agree," "Mostly Disagree," "Strongly Disagree," or “Don’t Know/Not Sure" to a variety of statements, including "Hypnosis is useful in helping witnesses accurately recall details of crimes," and "Listening to music by Mozart will increase your intelligence." Amongst these was the statement "I am more intelligent than the average person."

The researchers then combined the samples and weighted respondents to bring the survey population in line with the sex, age, and ethnicity (white vs. nonwhite) demographics of the United States as indicated by the 2010 census. No correction was needed for education levels as those of the survey population already approximated those of the broader U.S. population. After the corrections, the researchers found that 65% of respondents mostly or strongly agreed that they are more intelligent than average. Just 23% disagreed. The rest answered "Don't Know/Not Sure."

Percentages of participants reporting level of agreement with the statement, "I am more intelligent than the average person". Weighted to 2010 U.S. Census categories for sex, age, and race/ethnicity.

Men and individuals under the age of 44 had particularly high opinions of their intelligence. Seventy-one percent in each category thought they were more intelligent than the average person.

The survey adds another example in support of the notion of illusory superiority, a known cognitive bias in which people overestimate their own qualities and abilities in relation to their peers. Individuals with less education are uniquely suspectible to this effect, and this was again demonstrated in the current study.

A potential flaw of the current study is that the statement "I am more intelligent than the average person" was very broad and open to interpretation.

"If people define “average” differently, perhaps based on who they encounter regularly, then more than 50% of respondents might report greater than average intelligence," the researchers wrote.

Another example: If respondents perceived the "average person" as another American, then the study's result clearly is evidence of intelligence overestimation, as the result should logically be around 50%. However, if respondents were comparing themselves to other humans throughout the world, the high proportion might make a little more sense. Intelligence is highly correlated with education, and Americans tend to be more educated on average than other humans.

"The endurance of the smarter-than-average effect is consistent with the possibility that a tendency to overrate one’s own abilities is a stable feature of human psychology," the authors conclude.

Source: Heck PR, Simons DJ, Chabris CF (2018) 65% of Americans believe they are above average in intelligence: Results of two nationally representative surveys. PLoS ONE 13(7): e0200103. https://doi.org/10.1371/journal.pone.0200103