But I wore the juice.
— McArthur Wheeler, 1995
This article just mentions an old study (1999) showing that, when asked to rate their performance at various tasks relative to peers, the stupidest / most inept participants were also the worst judges of their own abilities, rating themselves as far above average. Everyone tends to think they’re above average in many circles — attractiveness, intelligence, skill — but it turns out there’s an inverse relationship between one’s aptitude and one’s self-rating without even adjusting for inaccuracy (for which the relationship has an even higher factor).
Last year, I was given some related statistics in a lecture (disclaimer: I’m never going to find the source, and I’m foggy on the details, but “self-efficacy” would be the keyword). At an American university, students (unsure of sample size) were simply asked about their intelligence relative to their classmates. Do you think you’re above average? In the top 10%? In the top 1%? Turns out 100% of students interviewed believed they had above-average intelligence. I don’t remember the other two figures, but the skew was ridiculous (something like 50% of them believed they were in the most intelligent 10%, and 25% thought they were in the top 1%).
Models of ego protection and the cognitive miser suggest we carry these beliefs to remain emotionally healthy, and to avoid wasting our precious conscious thought on stressful self-inspection.