Intelligence tests consist of a series of tasks that measure the ability to create abstract concepts, learn, and master new situations. The most common intelligence tests are the Stanford-Binet test intelligence test and Wechsler's intelligence test. Stanford-Binet's intelligence test is the American adaptation of the French Binet-Simon intelligence test, and was first used by Lewis Terman, a psychologist at Stanford University, in 1916.
The test result is expressed in Intelligence Quotient (IQ) units. This concept was first proposed by the German psychologist William Stern and adopted by Lewis Terman in the Stanford-Binet intelligence test. At first, IQ was measured as the ratio of a person's mental age to their actual age, multiplied by 100. For example, if a 10-year-old child reached the level of achievement of an average 12-year-old child, his IQ would be: (12/10) X 100 = 120. However, there are few tests that include calculating mental age, but the test result is expressed to as an IQ. Today, IQ is calculated based on the static percentage of people expected to have a specific IQ. The results of intelligence tests have a normal distribution, meaning that most people achieve results around the middle of the distribution curve, and the probability of achieving results that are far from the middle of the curve suddenly decreases.
The average intelligence quotient (IQ) is 100, while the average centile is 50. The average score is between 25 and 75 centiles (IQ/sd15 90-110), and 50% of the total population falls within this range. A score of above 75 centiles (IQ/sd15 > 110) is above average and can only be achieved by less than 25% of the total population. The score that is above 90 centiles (IQ/sd15 > 120) is high above the average and can only be reached by 10% of the total population. IQ/sd15 131 or higher, or centile of 98 or higher means that a score within the upper 2% of the total population on the intelligence test is achieved, which is a condition for membership in Mensa.
The tests used for testing intelligence in Mensa are based solely on the images and the results of these tests do not depend on education, cultural background, or age.