What do IQ Tests Really Measure?
IQ tests and other standardized tests are common ways to assess people’s aptitude or “intelligence.” But do IQ tests really measure intelligence? The evidence suggests otherwise, despite much weight placed on the value of IQ tests in schools, courts, militaries, and other places. Below are the reasons why IQ tests are not actually good quantifiers of human intelligence.
- Human intelligence is immeasurable and varied. Howard Gardner’s theory of multiple intelligences argues that there are 8 intelligences which people may display in varying degrees. For example, a person could be spatially “intelligent” but not perform well in activities demanding musical “intelligence.” Although debated, Gardner’s theory highlights the limitations in testing human intelligence. Abilities such as interpersonal skills and emotional intelligence are not easily quantified in numbers.
- IQ tests are arbitrary and reflect cultural bias. The modern intelligence test originated from the Binet–Simon test, developed in the early 1900s to measure mental retardation of French school children. This test was then adapted and used to test intelligence in American school children for much of the 20th century. Test-takers from a non-western educational background are at a disadvantage and scores would be on average lower for non-western IQ test-takers. This does not mean that they are less intelligent, only that the test favors a particular type of knowledge.
- IQ tests do not measure actual intelligence, but instead performance on the test relative to other test-takers. Statisticians design IQ and standardized tests so that 50 percent of the people score below average and 50 percent score above average. If more than 50 percent of the test takers consistently score above average, statisticians will redesign the test to make it more difficult. Similarly, if more than 50 percent of the test-takers consistently score below average, the test will be redesigned to make it easier. In fact, since the test was developed, people in some countries have been coring an average of several points higher each successive generation. This is called the Flynn Effect.
- Intelligence is defined in different ways in different cultures and also across time. Intelligence is normative, meaning that it reflects a particular ideal of society, and is not a natural or absolute fact. If people cannot even agree as to what intelligence is, how could they possibly even begin measure it?
If IQs tests don't measure intelligence, what do they measure and why are they used?
IQ tests do not measure intelligence, as noted above. The only thing they can measure is how well a person scored on the IQ test, relative to the other people who took the same test. Institutions such as schools, the government, etc. use these tests to differentiate the individuals within a group of people in regards to certain types of knowledge or skills which are valued at a particular time, in a particular place, for a particular purpose. However, the type of knowledge which is valued is highly subject to manipulation and change. For this reason, it would not be possible to implement an IQ test which accurately measures intelligence.