IQ Test

By John M. Grohol, Psy.D.

An IQ test is a psychological measure of a person’s “intelligence quotient” (IQ).

Intelligence Quotient, or IQ, is a theoretical construct used by psychologists within standardized tests as a means of describing one’s intelligence level. In the most commonly-administered IQ test — the Wechsler Adult Intelligence Scale (WAIS) — an average score is 100; about 95% of IQ scores fall between 70 and 130. It is important to note that IQ is not real — is simply a philosophical construct psychologists have created to describe a subset of human functioning they believe to be subjectively important in modern society. (Because of this, unless an IQ test has been specifically adopted for a different culture or country — and the most popular one has — IQ tests are very culturally specific and may be invalid when used in other cultures.)

IQ tests involve the measure of two primary components — verbal and performance. Because the performance portion of the IQ test requires physical manipulation of objects in front of the testing psychologist, a legitimate IQ test cannot be taken online. All of the so-called “IQ tests” you see online are invalid — none have been validated against real-world IQ tests with peer-reviewed journal publications.

When an IQ test is scored, three primary scores are obtained — verbal IQ, performance IQ, and the full scale IQ. The full scale IQ is what is commonly referred to as one’s “IQ score” by laypeople. Most people perform better in one component over the other in IQ testing (one either has a strength in verbal or performance).

How Are Verbal and Performance IQ Scores Obtained?

These two sections of the IQ test are divided into subscales, each measuring a different component of IQ.

Verbal scales

  • Information: 29 questions – a measure of general knowledge.

  • Digit Span: Subjects are given sets of digits to repeat initially forwards then backwards. This is a test of immediate auditory recall and freedom from distraction.
  • Vocabulary: Define 35 words. A measure of expressive word knowledge. It correlates very highly with Full Scale IQ
  • Arithmetic: 14 mental arithmetic brief story type problems. tests distractibility as well as numerical reasoning.
  • Comprehension: 16 questions which focus on issues of social awareness.
  • Similarities: A measure of concept formation. Subjects are asked to say how two seemingly dissimilar items might in fact be similar.

Performance scales

  • Picture Completion: 20 small pictures that all have one vital detail missing. A test of attention to fine detail.

  • Picture Arrangement: 10 sets of small pictures, where the subject is required to arrange them into a logical sequence.
  • Block Design: Involves putting sets of blocks together to match patterns on cards.
  • Digit Symbol: Involves copying a coding pattern.
  • Object Assembly: Four small jig-saw type puzzles.

You cannot “fake” your performance on an IQ test. Either you have the abilities or knowledge tested on, or you don’t. Each subscale test starts off with easy questions or problems, and gets progressively more difficult with each successive question or problem. Only geniuses (those scoring higher than 130 on full scale IQ) will be able to answer all of a scale’s questions or solve all of its problems.

People who score generally between 70 and 130 are considered to be within the normal range of IQ functioning, where 100 is the theoretical average. Those scoring 130 and above are significantly smarter than the average population, and those scoring 70 and below are significantly less smart than the average population.


    Last reviewed: By John M. Grohol, Psy.D. on 21 Jul 2010