What Is IQ and How Is It Measured?

IQ Scores Can Change the Way Your Child Is Educated

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IQ, or Intelligence Quotient, is a measure of relative intelligence determined by a standardized test. The first intelligence test was created in 1905 by Alfred Binet and Théophile Simon to determine which French school children were too “slow” to benefit from regular instruction. Binet came up with the idea of mental age when he noticed that children are increasingly able to learn difficult concepts and perform difficult tasks as they get older.

Most children reach the same level of complexity at about the same time, but some children are slower reaching those levels. A 6-year-old child who can do no more than a 3-year-old has a mental age of 3. 

Mental Quotient Versus Intelligence Quotient

The idea of a "mental quotient" was first developed by Wilhelm Stern, a German psychologist. Based on the work of Binet, he divided the mental age by the chronological age to get a “Mental Quotient.” A 6-year-old able to do only what a 3-year-old can do has a Mental Quotient of .5 or ½ (3 divided by 6). 

It was Lewis Terman, an American psychologist, who revised Binet's test to create the Stanford-Binet intelligence test (which is still in use). He also developed the idea of multiplying the Mental Quotient by 100 to remove the fraction -- and the Intelligence Quotient (IQ) was born.

Using measurements developed by Stern and Terman, the IQ test became a standard tool for classifying individuals based on normative scoring.

Here's how the scoring works:

  • Mental Age/Chronological Age X 100 = Intelligence Quotient
  • The 6-year-old with the Mental Quotient of ½ has an IQ of 50.
  • The majority of people have an IQ between 85 and 115.

It's important to know that, while the Stanford-Binet test is still in use, it is no longer the only (or even the most popular) IQ test.

Other tests such as the Wechsler and Woodcock-Johnson tests are more commonly used in America. In addition, while typical IQ tests can be useful, they may not be completely accurate when measuring the intelligence of people with developmental differences or learning disabilities. IQ tests such as the TONI have been developed to measure non-verbal IQ.

How Are IQ Scores Used?

IQ tests are now given to help schools determine the kind of academic accommodations children need in school. Children who get an IQ score of 70 and below qualify for special accommodations in school. That is two standard deviations below the center average of 100. Children who score two standard deviations above the center (an IQ score of 130) do not always qualify for special accommodations.

Of course, in both cases, the IQ score alone is not what determines the need for special accommodations. Children with a score higher than 70 can also qualify for special accommodations if they have a learning disability such as dyslexia. Even gifted children, generally considered to be those with IQ scores of 130 and higher, can qualify for special accommodations if they have a learning or developmental disability. These children are known as twice-exceptional.

Twice-exceptional children may, however, have found ways to work around their disability.Though they may not shine academically, they are average students. As a result, the giftedness hides the disability and the disability hides the giftedness. They end up getting no accommodations for either exceptionality.

What is the Significance of IQ for Gifted Children?

People understand that the child with an IQ of 70 will need some special accommodations in school. When you understand what the IQ score means, it is easy to see why. An eight-year-old child with a mental age of under six will need some help doing what most other eight-year-olds can do.

Now consider the eight-year-old with the IQ of 130. It should be just as clear that a child with that score needs special accommodations. He has the mental capacity of most ten-year-olds. Asking an eight-year-old with an IQ of 130 to do the work of average eight-year-olds is like asking a ten-year-old to do that work. An eight-year-old with an IQ of 145 has the intellectual capacity of a child of eleven and a half years old. Would we ever consider giving an eleven and a half-year-old work meant for an eight-year-old?

The higher or lower the IQ, the greater the discrepancy between chronological age and intellectual age. While we always want to make sure that children with low ​IQ scores get the services they need, we should also want to make sure that children with high IQ scores get the services they need. Of course, it's also important to remember that a gifted child of eight may be able to do higher level academic work but may still have the social and emotional development of a younger child!

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