When people talk about “average” human intelligence, statistically they’re talking about the mean, or average, of scores made available from scientifically accepted IQ tests. Over time, human beings have gotten smarter, so the “average IQ” we see now is significantly higher than it was a hundred years ago. Scores are evaluated periodically, and the tests adjusted, so that the average score on most intelligence tests such as the Wechsler Adult Intelligence Scale and the Stanford-Binet Intelligence Scale’s mean score is 100.
The distribution of the scores on these tests form what is known as the IQ bell curve, where the scores layout in what’s known as a standard distribution, seen below.
The Meaning of the IQ Bell Curve and IQ Scores
The IQ bell curve helps categorize where people fall along the scale of intelligence, and does so in a neatly compartmentalized way. If you look at the graph above, you can see that there are equal parts above and below the mean of 100. Roughly 68% of humans will have IQ scores that fall between 85 and 115, or one standard deviation above or below the mean. Expanding the curve out a little further to two standard deviations, you’ll find that over 95% of people will fall between 70-130 on the IQ scale. The further out you go you will find fewer and fewer people, as only 4.2% of IQ scores fall between 55-70 and 130-145. The next level of scores above or below these levels are extremely rare, as people with IQs below 55 are intellectually impaired, while people with IQs above 145 are exceptionally gifted and often considered geniuses.
An individual who completes an intelligence test with a cumulative score between 90 to 109 would be classified as having an average IQ. Roughly 50% of the population falls into this category. In general, IQ scores are categorized as follows:
- < 67 Extremely Low
- 70-79 Borderline
- 80-89 Below Average
- 90-109 Average
- 110-119 High Average
- 120-129 Superior
- > 130 Genius to Near Genius
It’s important to note that the scores above are designed to reflect overall intelligence, while it’s generally believed that there are many different types of intelligence that an individual may possess. So while someone may be seen as having a low IQ by their overall score, it’s quite possible that these people may be average or even well above average in certain types of intelligence.
Can You Improve Your IQ?
People with wide ranges of IQs have proven to be wildly successful in all walks of life. However, some people who have received a below average IQ score or even an average IQ score have sought to improve their intelligence score. While it’s generally accepted that genetics effect intelligence, people can take matters into their own hands to some extent to improve their IQ. You can read the link for specific tips, but in general, being healthy and exercising your brain much like you would your body, can help a person achieve a substantial improvement in cognitive function and overall intelligence.
What is Considered and Accurate IQ Test?
While quick IQ tests like the one available on this site can provide you with a generalized idea of your intelligence, it is not an official score that can be used to gain entry to high IQ societies like Mensa, or used for career or educational screening purposes. There are a wide variety of generally accepted IQ tests that you can sign up for and have administered by a psychiatrist or other trained professional. It’s important to note that certain tests are more or less focused on verbal and language skills to provide scores that are not impacted by someone’s language skills or culture, particularly people taking the test in a second language.