Since ancient times, people have tried to invent a way to measure their own and other people's mental abilities. The first attempts to create something like tests that evaluate human intelligence were made at the end of the XIX century, and in 1905 French psychologists Alfred Binet and Theodore Simon developed a test designed, they say, to assess the age of human consciousness. In 1915, the American psychologist from Stanford University, Lewis Terman, improved this test and after that it became known as the Stanford-Binet test. The term IQ - intelligence quotient or mental quotient was coined by the German psychologist Wilhelm Stern in 1912.

IQ scores do not always depend on a person's level of education, although test takers with higher education tend to score higher on average. In general, IQ tests reveal how well a person thinks - draws logical conclusions and notices logical connections, systematizes information, understands complex ideas, and is able to think abstractly. IQ tests do not measure the level of knowledge in any areas, they measure the ability to logic, spatial, associative and verbal thinking.

At present time, there are several popular IQ tests in the world, the most famous are the Eysenck test, the Wechsler test, the Raven test, the Amthauer test and the Cattell test. The IQ of the average person on these tests is in the range of 85 to 115 points, about 68% of people who have ever taken an IQ test demonstrate such results.

In different tests, the scale from mental retardation to genius also fluctuates, but in general, psychologists and psychiatrists regard an IQ level below 70 points as different degrees of mental retardation. The most commonly used scoring scale is:

- less than 24: profound mental retardation;

- 25-39: severe mental retardation;

- 40-54: moderate mental retardation;

- 55-69: mild mental retardation;

- 70-84: borderline mental disorder;

- 85-114: average intelligence;

- 115-129: intelligence is above average;

- 130-144: moderately gifted;

- 145–159: very gifted;

- 160-179: exceptionally gifted;

- 180 and above: profoundly gifted (geniuses).

Many psychologists are skeptical of online intelligence tests because they fail to give an accurate assessment of a person's true IQ level. Therefore, many advise taking the test not on the Internet, but with a professional psychologist.

Does this mean that people who score high on IQ tests are smarter? No, it doesn't. Human intelligence is a very complex system and depends on too many factors, including education, life experience, innate abilities, and even the environment in which it was tested. There are people with a fast type of thinking, there are those who also think productively, but much more slowly. Comparing both those and others, trying to understand who is smarter, is a futile exercise. In recent years, opinions have been heard more and more often that judging a person's intelligence based on the results of his IQ tests is an approach that should be abandoned.

In general, good IQ indicators can help in education, in building a career, but it does not always mean that a person will definitely achieve any heights in his business. Often high test scores were shown by people who did not mark any achievements, and vice versa - people with an average IQ achieved a lot thanks to perseverance, the ability to learn and the ability to respond adequately to circumstances.

Some interesting facts about IQ tests:

• IQ tests are often used to test military personnel in many armies of the world;
• IQ level in 20 percent of cases can be trained;
• breastfeeding in infancy in the future increases the level of IQ;
• people with high IQ are more likely to abuse alcohol;
• people with high and very high IQ levels are only 3% of the population;
• in recent years there has been a downward trend in the general human level of IQ.

Resources: psyfactor.org; www.techinsider.ru; www.sport-express.ru

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