You probably think you have above average intelligence. I would agree with you, since you are reading my blog.
It stands to reason that 50% of the population has above average intelligence, and 50% are below average. However, a study by Heck, Simons and Chabris has shown that 65% of Americans consider their intelligence to be above average.
This is not a surprise. Intelligence is considered a good thing, and we like to think well of ourselves. Therefore, to boost our own self-esteem, we consider ourselves above average. It is a kind of self-serving bias.
The effect was greater for men than for women. 70% of men, and 60% of women rated themselves as more intelligent than average. I will leave it to you to speculate why that may have been!
A self-serving bias is only one of several biases probably at play when you are asked how intelligent you are. You may also be affected by who you hang out with, and what you consider to be intelligence.
The statistics showed that those of a lower intelligence were more likely to overestimate, and those of a higher intelligence more likely to underestimate. This could be partly because people are likely to mix with others of a broadly similar mentality and intelligence. For example, those clever enough to get into university are then going to spend their time with other undergraduates and graduates. People they see all around them are very clever, so what they consider “average” may actually be far higher than the national average actually is.
Also, IQ may not be the only thing people are thinking about when asked about intelligence. Maybe someone who would not do well at exams considers themselves very streetwise, and that is the kind of intelligence which is relevant to them and their situation.
It is likely, though, that the overriding reason for 65% considering themselves as above average is the self-serving bias. We all want to feel good about ourselves.