Measuring Intelligence With Intelligence Tests

One of the first people to create an intelligence test was a scientist named Francis Galton.

He used the biometric method, which attempted to test intelligence by using physiological measures such as the strength of a persons grip.

However Galton soon discovered that there was little correlation between how strong someone was and their performance on the intelligence test.

Binet-Simon Intelligence Test

After Galton’s work, two French scientists named Alfred Binet and Theodore Simon devised a new way to test intelligence called the Binet-Simon Scale.

This intelligence test measured someone’s intelligence using the performance method, which involved testing intelligence based upon someone’s ability to give correct answers to a series of questions.

To help compare intelligence between different types of people, the Binet-Simon Scale used a measure called mental age.

For example, if on average a group of nine year olds score twenty correct questions, and then a child who is seven years old scores the same amount, then that seven year old child is said to have a mental age of nine.

In general, mental age should rise as a person grows older. So the older they are, the better they will do on the test.

Stanford-Binet Intelligence Test

Today we know the Binet-Simon Scale as the Stanford-Binet Intelligence Scale, because it was translated from French into English by the Stanford psychologist Lewis Terman.

One of the things Terman was interested in was whether children who performed well on intelligence tests did better in life, compared to children who performed poorly on intelligence tests .

To measure this he started a longitudinal study (something that measures behaviour over a period of time).

After Terman’s death the study was continued for around seventy years, and the results backed up what Terman had initially suspected.

The study found that people with higher intelligence test score were much more likely to be wealthier, happier and healthier than people with lower levels of intelligence.

This result was hardly surprising however, as intelligence is defined as the ability to think clearly and function effectively. Therefore the higher a person’s intelligence is, the better they should do in society.

The Wechsler Intelligence Test

David Wechsler was a psychologist who created a series of intelligence tests known as the Wechsler Scales.

There are three intelligence tests in the Wechsler Scales :

• The Wechsler Preschool And Primary Scale Of Intelligence

• The Wechsler Intelligence Scale For Children

• Wechsler Adult Intelligence Scale

One of the major advantages of the Wechsler Scales is that unlike the Stanford-Binet intelligence test which only measured a persons general level of intelligence, the Wechsler Scales measured different types of intelligence.

Note : The tests are called “scales” because the questions get progressively harder.

There are two types of intelligence measured by the Wechsler scale : verbal intelligence and performance intelligence.

Both of these contain a number of subtests (7 subtests for verbal intelligence and 6 subtests for performance intelligence).

Verbal Intelligence Test

• Information : A persons level of general knowledge

• Comprehension : How well you can understand questions and grasp concepts.

• Arithmetic : A persons mathematical abilities.

• Similarities : Measures abstract thought.

• Digit Span : Measures attention span.

• Vocabulary : How many word meanings you know.

Performance Intelligence Test

• Digit Symbol : Mental flexibility with random symbols.

• Picture Completion : Ability to notice differences between two similar pictures.

• Block Design : Mentally construct printed designs in your head.

• Picture Arrangement : Arrange pictures in a logical order.

• Object Assembly : Place the correct part in relationship to a whole.

IQ

Once a person has completed all the intelligence tests they can then be given two separate IQ scores.

They would have a verbal IQ and a performance IQ, with individual scores for each sub test within the verbal and performance categories.

Both of these scores (verbal + performance) can then be combined to give an overall IQ score.

Summary

• One of the first intelligence tests created was the biometric test, which examined the relationship between physical strength and intelligence.

• The Binet-Simon Scale used the performance method, which measured intelligence with a series of progressively more difficult questions.

• Mental age was a value given to compare scores between people.

• One of the disadvantages of mental age is that it is unstable, which means it increases as a person grows older. This makes comparisons between mental ages and intelligence scores of little value.

• Lewis Terman translated the Binet-Simon scale into English, and called it the Stanford-Binet Intelligence Scale.

• Terman suspected that those with higher levels of intelligence will do better in life. This was later shown to be the case.

• The Wechsler scales measure different types of intelligence, and not just a persons overall level of intelligence.

• The Wechsler scales involved 11 tests. 7 in the verbal intelligence category, and 6 in the performance intelligence category.

• The Wechsler scale can provide someone with a score for verbal and performance intelligence. Both of these scores can be combined to give an overall IQ score.

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