A visitor to our Quora site asked about the meaning of IQ. In this post, I will attempt to describe what IQ really means. For a more formal description of the development of the concept of IQ, I refer you to an earlier post at: https://www.intelligence-and-iq.com/why-were-iq-tests-developed-originally/
Intelligence, like athleticism, is a multi-faceted human ability. If we want to compare two people to determine which of them is more athletic, we could develop tests of speed, strength, endurance, agility and a host of other physical skills. The ancient Greeks invented the decathlon to enable them to compare the athletic abilities of people and they measured athleticism as the sum of the scores on tests of these attributes.
In a similar way, IQ tests such as the WAIS and the Stanford-Binet, attempt to assess the various components of intelligence, such as short term memory, vocabulary, comprehension, matrix reasoning and arithmetic skills and then add the scores on these attributes to render a single number. By recording the performance of thousands of people on these tests, the companies who develop them record the average score and the standard deviation for a cohort of people of various ages. This process, called “norming the tests,” structures the scale so that the mean IQ is set to 100 and (typically) the standard deviation is set to 15 or 16. This enables these companies to convert the score you achieved on the tests into a number called your IQ that yields the percentage of people who scored at or below the score you achieved.
This means that if your IQ is above 100, then you scored above the average person your age. If your IQ is 115 on a test with a standard deviation of 15, you scored as well or better than 84% of the people your age, and if your IQ is 130, then you scored better than 97.6% of that population. If you have a high IQ, it means that you have performed much better than most people on the IQ tests. But what are the implications?
There is a strong correlation between IQ and the ability to learn. For this reason, occupations such as law, medicine and the natural sciences, requiring a capacity to work with complex concepts, is populated with mostly high IQ individuals, while unskilled jobs are typically filled with people of lower IQ. These are averages, so there are some high IQ people who work in unskilled jobs and a smaller number of below-average IQ people who work in the professions. Careers in theoretical physicists, mathematics and some other arcane subjects are populated almost exclusively by high IQ people, because the skills needed for these careers are very similar to the skills tested in IQ tests.
However, to put the discussion of IQ in perspective, we revert to our analogy with the measure of athleticism. You might challenge a person with a higher AQ (athletic quotient) than you to a 100-meter dash and win, because that person may have achieved a high AQ through a high performance in strength and endurance tests rather than speed. Similarly, Richard Feynman, one of the greatest scientific minds of the 20th century, had a reported IQ of 125, much below that of many of his colleagues of lesser capability, yet outperformed them in achievement. It has been suggested Feynman’s low IQ score was the result of a poor score in the language section of the IQ test. My theory (purely speculative) is that he merely didn’t perform up to his potential on that fateful day or days that he took the test. Remember how you felt in early high school when someone shoved a test under your nose and told you it didn’t count toward your final mark, but you must complete the test anyway. I’ve observed many high school students who achieved low marks on multiple-choice tests, because they became bored half way through the test and shut down their mental engine. IQ tests provide our best measure of intelligence, but they should never be taken too seriously in individual cases.
