What Is the Average IQ?

How different IQ tests classify IQs

A woman with an average IQ
What exactly is the average IQ?. Justin Lewis / Getty Images

Intelligence tests are one of the most popular types of psychological tests in use today. Ever since the first IQ tests emerged, attempts to classify IQ have followed. While different test publishers utilize different scoring systems, for many modern IQ tests the average (or mean) score is set at 100 with a standard deviation of 15 so that scores conform to a normal distribution curve.

  • 68 percent of scores fall within one standard deviation of the mean (that is, between 85 and 115)
  • 95 percent of scores fall within two standard deviations (between 70 and 130)

Why is the average score set to 100?

Psychometricians utilize a process known as standardization to make it possible to compare and interpret the meaning of IQ scores. This process is accomplished by administering the test to a representative sample and using these scores to establish standards, usually referred to as norms, by which all individual scores can be compared. Since the average score is 100, experts can quickly assess individual test scores against the average to determine where these scores fall on the normal distribution.

Classification systems can vary from one publisher to the next although many do tend to follow a fairly similar rating system For example, on the Wechsler Adult Intelligence Scale and the Stanford-Binet test, scores that fall between 90 and 109 are considered "Average."  On these same tests, scores that fall between 110 and 119 are considered "High Average." Scores between 80 and 89 are classified as "Low Average."

What Exactly Are IQ Tests Measuring?

Intelligence tests are designed to measure crystallized and fluid intelligence. Crystallized intelligence involves your knowledge and skills you have acquired throughout your life while fluid intelligence is your ability to reason, problem-solve and make sense of abstract information.

Fluid intelligence is considered independent of learning and tends to decline in later adulthood. Crystallized intelligence, on the other hand, is directly related to learning and experience and tends to increase as people grow older.

IQ tests are administered by licensed psychologists. There are different kinds of intelligence tests, but many involve a series of subtests that are designed to measure mathematical abilities, language skills, memory, reasoning skills and information-processing speed. Scores on these subtests are then combined to form an overall IQ score.

It is important to note that while people often talk about average, low and genius IQs, there is no single IQ test. Many different tests are in use today including the Stanford-Binet, the Wechsler Adult Intelligence Scale and the Woodcock-Johnson Tests of Cognitive Abilities. Each individual test in different in terms of exactly what is being measured, how it is scored, and how these scores are interpreted.

So What Does It Mean to Have an Average IQ?

Your IQ score might be a good general indicator of your reasoning and problem-solving abilities, but many psychologists suggest that these tests don't tell the whole story.

A few things they don't measure are practical skills and talents. You might have an average IQ score, but you might also be a great musician, a creative artist, an incredible singer or a mechanical whiz. Psychologist Howard Gardner developed a theory of multiple intelligences designed to address this perceived shortcoming in popular conceptions of IQ.

Researchers have also found that IQ scores can change over time. One study looked at the IQ's of teenage subjects during early adolescence and then again four years later. The results revealed that scores varied as much as 20 points over that four-year period.

IQ tests also fail to address things like how curious you are about the world around you and how good you are at understanding and managing emotions. Some experts, including writer Daniel Goleman, suggest that emotional intelligence (often referred to as EQ) might even be more important than IQ. And researchers have found that while having a high IQ can indeed give people and edge in many areas of life, it is certainly no guarantee of life success.

So don't stress out if you're not a genius since the vast majority of people aren't geniuses either. Just as having a high IQ doesn't ensure success, having an average or low IQ doesn't ensure failure or mediocrity. Other factors such as hard work, resilience, perseverance and overall attitude are important pieces of the puzzle.

Learn more about IQ:

References

Ramsden, S., Richardson, F. M., Josse, G., Thomas, M. S. C., Ellis, C., Shakeshaft, C., Seghier, M. L., & Price, C. J. (2011). Verbal and non-verbal intelligence changes in the teenage brain. Nature, 479, 113-116.doi:10.1038/nature10514.

Wilson, J. (2014, Feb. 19). What your IQ score doesn't tell you. CNN Health. Retrieved from http://www.cnn.com/2014/02/19/health/iq-score-meaning/

Continue Reading