What Is the Average IQ?

Understanding what an average IQ score can tell you (and what it can't)

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IQ, or intelligence quotient, is a measure of your ability to reason and solve problems. It essentially reflects how well you did on a specific test as compared to other people of your age group. While tests may vary, the average IQ on many tests is 100, and 68 percent of scores lie somewhere between 85 and 115.

While IQ can be a predictor of things such as academic success, experts caution that it is not necessarily a guarantee of life success.

Sometimes people with very high IQs do not fare so well in life, while those with average IQs may thrive.

Average IQ Scores

The measurement of intelligence has long been a hot topic in psychology and education—and a controversial one. 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.

In order to understand what an average IQ score is and what it means, it is essential to first understand how IQ is measured. 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.

  • On many tests, a score of 100 is considered the average IQ.
  • 68 percent of scores fall within one standard deviation of the mean (that is, between 85 and 115). That means that nearly 70 percent of all people score within plus or minus 15 points of the average score.
  • 95 percent of scores fall within two standard deviations (between 70 and 130). Outliers beyond those points represent only a small portion of the population, which means that only a small percentage of people have a very low IQ (below 70) or a very high IQ (above 130).
  • Scores below 70 may represent the presence of some sort of developmental or learning disability while scores over 130 may indicate giftedness.

    How IQ Is Calculated

    Historically, IQ tests have been scored in one of two ways. In the first method, a person's mental age was divided by their chronological age and then multiplied by 100. The other methods involve comparing scores against the scores of others in the individual's same age group.

    In this method, 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 median score is 100, experts can quickly assess individual test scores against the median 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 IQ scores.
    • On these same tests, scores that fall between 110 and 119 are considered high average IQ scores. Scores between 80 and 89 are classified as low average.

      So in most cases, if you receive an IQ score of around 100, then you have what is considered an average IQ. Don't worry—you are in good company. Most people score within one standard deviation of this average.

      IQ Tests and the Measuring of Intelligence

      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.

      A few of the most common IQ tests in use today include:

      • The Wechsler Adult Intelligence Scale for Adults
      • The Wechsler Intelligence Scale for Children
      • The Stanford-Binet Intelligence Scales
      • The Kaufman Assessment Battery for Children
      • The Cognitive Assessment System
      • The Differential Ability Scales
      • The Woodcock-Johnson Tests of Cognitive Abilities

      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 afore-mentioned Stanford-Binet and the Wechsler Adult Intelligence Scale, as well as the Woodcock-Johnson Tests of Cognitive Abilities. Each individual test is different in terms of exactly what is being measured, how it is scored, and how these scores are interpreted.

      Controversies Over IQ

      Ever since the inception of the very first tests of intelligence, both academics and armchair psychologists have debated differences in intelligence, including possible connections between IQ and race. In addition to connections between race and IQ, people have also attempted to connect IQ disparities to other factors such as sex differences and nationality. One important factor to also note is that overall, IQ scores have been rising worldwide, a phenomenon known as the Flynn effect.

      Race and IQ Scores

      During the 1920s, the US Army utilized IQ testing on recruits and found that different populations showed group differences in average IQ scores. Such findings helped fuel the eugenics movement and those who supported racial segregation.

      The 1994 book The Bell Curve rekindled the argument and controversy, as the book promoted the notion that racial group differences in average IQ scores were largely the result of genetics. Critics suggest that such group differences are more accurately a product of environmental variables.

      Such arguments over race and IQ are a reflection of the age-old nature versus nurture debate. Are certain traits, characteristics, and abilities more heavily influenced by genetics or by environmental causes? Those who believe that race is a determinate of IQ are taking the side of nature, suggesting that heritability is the primary determinant of IQ.

      However, research has found that while genetics do play a role in determining intelligence, environmental factors also play an important role. Some factors that have been linked to group differences in average IQ scores include education, health and nutrition, socioeconomic status, testing bias, and minority status.

      In response, the American Psychological Association formed a special task force led by psychologist Ulric Neisser to investigate the claims made by the book. They found no direct evidence to support genetic explanations for test score differences between blacks and whites. Instead, they stated that at the present time, there are no known explanations for such differences.

      Nationality Differences in Average IQ Scores

      Studies of national cognitive ability suggest that there are differences in IQ scores among different nations. Such studies remain limited, but some explorations of this topic have been conducted by creating estimates of average IQ for different nations. Such differences may be largely linked to environmental influences such as socioeconomic factors, literacy rates, educational rates, and life expectancy.

      According to research conducted by Richard Lynn and Tatu Vanhanen, Hong Kong had the highest average IQ at 108 while Equatorial Guinea had the lowest at 59. Average group IQs of some other countries included the United States at 98, the United Kingdom at 100, and Italy at 102.

      Sex Differences in Average IQ Scores

      Over the years, some researchers have argued that either males or females held an advantage in terms of IQ while others have argued that there are no significant differences between men and women. One study found that while there was no average difference in IQ scores between men and women, there tended to be more variability in IQ scores among men.

      Research has found that there are slight differences in the performance of verbal and spatial tasks, with women performing better on some verbal tasks and men performing better on some spatial ability tasks. However, researchers believe that this disparity is only partially due to biological differences and is also influenced by culture, experiences, and education.

      What an Average IQ Score Means to You

      While some limited generalizations can be made in relation to your average IQ score, keep the following in mind:

      • It means you have average reasoning and problem-solving skills. 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.
      • An average IQ score might not tell the whole story about what you are capable of. 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.
      • IQ scores are not necessarily set in stone. 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.
      • Some experts suggest that EQ might matter even more than IQ. 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 an edge in many areas of life, it is certainly no guarantee of life success.

      A Word From Verywell

      Don't stress out if you're not a "genius"—the vast majority of people aren't geniuses either. Instead, most people are somewhere within a 15-point range of the average IQ score.

      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.

      Sources:

      Halpern, DF, et al. The science of sex differences in science and mathematics. Psychol Sci Public Interest. 2007;8(1): 1-51. doi: 10.1111/j.1529-1006.2007.00032.x

      Johnson, W, Carothers, A, & Deary, IJ. Sex differences in variablity in general intelligence: A new look at the old question. Perspectives on Psychologial Science. 2008;3(6):518-531. doi: 10.1111/j.1745-6924.2008.00096.x

      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. 2009; 479:113-116. doi:10.1038/nature10514

      Rindermann,H. The g-factor of international cognitive ability comparisons: The homogeneity of results in PISA, TIMSS, PIRLS and IQ-tests across nations. European Journal of Personality. 2007;21(6): 67−706. doi: 10.1002/per.634

      Schaffer, DR & Kipp, K. Developmental Psychology: Childhood and Adolescence. Belmont, CA: Wadsworth; 2010.

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