A series of tests used to determine the intelligence of an individual in relation to other people the same age. Tests are specific to a particular culture, and do not reflect creativity or motor skill aptitude.

There are many IQ tests used today. The most commonly used in the U.S. and U.K for adults are the Catell B, Culture Free, and Wechsler tests. Each of these uses different scales; therefore, the score represents statistical cutoffs in the population. For example, on the Catell B only 2% of people, on average, are able to score above a 148—therefore, 148 is arbitrarily designated genius. Similarly, the 2% mark is 133 in the Culture Free, and 132 in the Wechsler. The score is very much related to which test was used. Furthermore, different tests are used for different age groups.

Generally, scores around 100 are average, while scores below 70 indicate some degree of mental retardation. Again, scores are test and age dependent, so a child that scores 120 on one test will not necessarily score a 120 on a separate test as an adult. And someone who scores 140 on the Catell B will clearly not score 140 on the Wechsler—he will more likely score around 125.