The number shows how your performance compare to those of others your age. A score of 116 or more is regarded as above average. A IQ of 130 or higher indicates a high level of intelligence. Mensa, the high IQ society, admits members with IQs in the top 2%, which is generally 132 or above.
IQ tests usually includes questions on reasoning, arithmetic, vocabulary, and information processing speed. The test also may include questions on memory, drawing, writing, and visual perception. The amount of time it takes you to take the test also is considered.
The IQ test measures your ability to understand and apply instructions, solve problems, think logically, and make judgments based on evidence. It does not measure your intelligence itself; that is, your capacity for learning at any given moment in time. The test also does not measure your artistic, musical, linguistic, or other skills or abilities. These are known as "fluid" or "interactive" intelligence factors. The IQ test can only measure "crystallized" intelligence factors such as knowledge and skill training acquired through practice.
Your score may be low because: (1) You took the test seriously but found it difficult. (2) You did not get enough sleep the night before. Being half asleep on test day will lower your score. (3) You have a family history of mental illness. This would be apparent from reading about it in our personal histories section of the test page.
The average test score is 100, and anyone who achieves a score of 132 or above (the 98th percentile) on the Mensa exam gets admitted to the Mensa society, an international high-IQ group. According to Mensa, an IQ of 135 to 158 places you in the top 1% of the population. So, yes, 158 is a very high IQ score.
However, not all high IQ scores are equal. While everyone agrees that an IQ of 160 or more is extremely high, some researchers consider an IQ of 150 or higher to be superhigh. Others place the cutoff at 140 or 145. Still others limit inclusion to those with an IQ of 130 or higher. Finally, some limit admission to those with an IQ below 120. It's difficult to say where these different thresholds should be set because studies have shown that there is no correlation between how high your IQ is and how well you do in life. The only way to know if you have a high IQ is by taking the test used by Mensa - the Wechsler Scale of Intelligence, or WAIS-IV. This is a standardized test that most schools use to measure cognitive ability.
However, it's not the only one out there. The number of people who have ever been admitted to Mensa ranges from about 70 to 120 per million. That means that approximately 1 in 7500 people has an IQ of 158 or higher.
An IQ test yields a score of 100 on average. The majority of persons fall between the ages of 85 and 114. A high IQ is defined as a score of 140 or higher. A genius IQ is one with a score of more than 160. This number is extremely rare.
The highest recorded IQ score on an official test was 188, by Soviet psychologist Leonid S. Vladimirov. He tested several highly intelligent people in order to determine how much intelligence can be increased through practice. The results showed that some individuals could improve their scores by as much as 20 points after just a few hours of study.
The lowest recorded IQ score was 35; two brothers named Stanley and Milton Geier were diagnosed with this condition. They were very poor-quality children who failed all their classes in school. However, they became famous when scientists discovered that they had an unusually high level of intellectual ability. Their mother noticed that they seemed to understand things other kids didn't grasp and so she brought them to see Dr. Lorna Hillyard, who diagnosed them with hyperthymic syndrome. They are now adults and live with their own family but are unable to hold down jobs or manage money because of their emotional instability.
Stanley and Milton Geier are not alone in having an IQ below 50. There are many others like them, mostly born into poverty and lacking any kind of education.