I have often been known to say that I don’t put much stock in IQ tests, to those who know me well. Certainly, it does not mean that IQ tests don’t matter, or don’t tell us anything. It simply means that the layperson often use it today to mean something very different than what it was originally intended to mean. As well, a lot of pop “IQ” quizzes have come up, thanks to the internet, adding to the confusion. So in this post, I will go over the history of IQ tests a little bit and talk about the current issues surrounding IQ tests.
(Note that a lot of the information in this comes from my lectures and class notes, so I am in the continuous process of finding primary sources for the information. Please be patient.)
At the end of the 19th century, a new law in France mandated that all children aged 6 to 14 must attend school. To accomplish this, it was necessary to devise a way to help children with learning disabilities so they might progress through the ranks instead of being stuck in the same class while their peers move on. Alfred Binet, along with his student Theodore Simon devised a test for this purpose called the Binet-Simon test which was published first in 1905. Subsequent revisions were made by Binet in 1908 and 1911, before he died.
The test was created by averaging the performance of students on several measures in several classrooms, and the results were cross-checked by conferring with the teachers. In other words, if Sally is considered by all of her teachers to be very smart and doing well in all of her classes, and she did very poorly on a measure of intelligence, it was considered to be useless in serving the purpose of the Binet-Simon test. The test measured performance of an individual student compared to the average of that age group. The purpose was to isolate those who were performing far under the average and put them in special classes where they can get extra help.
The Binet-Simon test was soon imported over to the United States of America, where it quickly gained popularity, albeit due to historically condemnable reasons. The Binet-Simon test was picked up by H.H. Goddard, a champion of the eugenics movement and used to prove the “superiority” of the Whites. It was used to curtail immigration of Jewish population to US during WWII on the basis of “lower intelligence”. This is the opposite of what Binet himself believed, i.e., that intelligence was a qualitative rather than quantitative characteristic, and was malleable and depended on the environment, and not solely dependent on genetics. He also stressed that IQ scores could only be compared amongst children with comparable backgrounds. I will elaborate on this more on the section about issues.
David Wechsler first published his test in 1939 and by the 1960’s, the popularity of his test overtook that of Binet’s. It has undergone several revisions by now and the WAIS IV and the WISC V are considered the gold standard in psychometric testing for intelligence.
Current measures of intelligence
The Wechsler Adult Intelligence Scale (WAIS IV) and Wechsler Intelligence Scale for Children (WISC V) have various sections with items that measure different kinds of intelligence. The sub-tests look at verbal comprehension, perceptual reasoning, working memory and processing speed. The tests have been standardized on large samples from both the USA and Canada, and people are scored against the “norm” (the normative range) of their own country. This does differ, as the average score of the Canadian sample is much higher than the US sample. There also exists a French version of the test. The administering of the WAIS and WISC are strictly regulated and a clinical psychologist who intends to administer it undergoes rigorous training before they are allowed to do it independently on actual clients.
IQ scores are often reported as a range, as opposed to a specific number. However, most IQ tests that have been rigorously standardized (so, not that 5 minute Facebook quiz you took 2 years ago) have been shown to be reliable. IQ is stable over time, given that you don’t suffer a traumatic head injury or infection, or one of the many things that could possibly affect your brain tissue. There’s quite a few of these neurodegenerative diseases and this is actually one of my main interests.
Given that IQ tests are based on normative scores in a population, it is important to stress that it’s really useful for identifying people at either ends of the spectrum. The average IQ is set at 100-110 points, above 130 is considered well above the average, below 70 is considered an intellectual disability. There are levels to this as well, eg., below 20 is severe intellectual disability and a case where the person would be completely unable to survive on their own and usually need a live-in caretaker. IQ scores are not really all that useful for distinguishing between people who fall within the normative range of intelligence.
There is some debate amongst psychologists on the issue of how to report and interpret the data. Some have questioned the utility of reporting it as a raw score (eg. a score of 122), as opposed to a percentile score (eg., Jane Doe scored in the 75th percentile, meaning they did better on the test than 75% of the population) to really drive home the point that the results are on a relative rather than absolute scale.
The average IQ changes over generations, and it is on an upwards trajectory. Criminals with an IQ of less than 70 are considered to be intellectually disabled and put in re-mediation programs rather than prisons. The debate surrounding this is that there might be criminals who were put in prison back in the 70’s or 80’s because they were above the cutoff at the time of their conviction, but would be below 70 and considered intellectually disabled now.
The IQ tests were initially based on a population that is very specific. The subjects measured were all white, middle-class males who were in the education system. As a result, there is some queries about the validity of IQ tests to measure intelligence in populations who fall outside of these parameters. There are issues with cultural interpretation of questions. Certain questions are simply not relevant to certain cultural lifestyles and therefore they would not be able to answer those questions. For example, suppose a question asks you the velocity of a bicycle going downhill at an inclination of 24° and an initial height of 38 meters. If you are from a remote island where bicycles are not a common means of transport and you have never seen or experienced riding a bicycle, you are not going to be able to answer the question. Rather, your question would be, “what is a bicycle?” That does not mean that cultures without experience with the items in a given IQ tests are not intelligent, or below a functioning level of intelligence. To administer the WAIS, you have to be fluent in the language, as does the client.
This is by no means a comprehensive list of all the issues, but it outlines some of the main points. That’s all, folks! If there are specific questions about IQ tests or the concept of IQ in general, feel free to comment and I will answer to the best of my ability.