In popular culture, the term IQ is everywhere. But do IQ exams really measure intelligence? It is often said that you need 120 points of IQ to be considered smart, but what does this really mean? Low IQ individuals are often seen as less capable, and people who boast about their IQ are often considered to be losers.
When people talk about IQ, what they really mean is intelligence, which is an objective and rigorous measurement of intellectual ability. But does it actually work? In this video, I want to find out where IQ came from, what it actually measures, what it can predict about your life, and what my IQ is.
I have never taken an official IQ test before, and honestly I don’t think I’m terribly smart. I have always considered my IQ to be just a little above average. To try and improve my score, I’m going to do a bunch of practice tests online, but I’m very skeptical about their accuracy.
The idea of intelligence testing goes back hundreds of years, but the first concrete breakthrough occurred in 1904. Tomorrow, I’m going to do an IQ test for real to see if the practice tests have helped me improve my score. quotient or IQ Spearman and Binet both had the same goal to measure intelligence but they used different methods Spearman used correlations while Binet used mental age and IQ scores to compare performance
Charles Spearman, an English psychologist, studied the grades of students in different subjects and wondered how their performance in one subject, such as English, would relate to their performance in another, such as math. One option was that the better a student did in math, the worse they would do in English, as they may have spent more time on math and had less time for English, thus negatively correlating the two. Another option was that performance in one subject would be completely unrelated to performance in another, as different subjects require different skill sets. The third option was that the better a student did in math, the better they would do in English, thus positively correlating the two.
A correlation coefficient can range from negative one to positive one, with negative one indicating a perfect negative correlation, meaning an increase in one variable corresponds to a precise, predictable decrease in the other variable. Similarly, a correlation of positive one indicates a perfect positive correlation. A correlation of zero indicates no relationship between the two variables and any value between 0 and 1 indicates a positive correlation, but with some random spread.
When Spearman analyzed his data, he found a clear positive correlation, with the correlation coefficient being 0.64. Not only did he find this correlation between math and English, but also between the other subjects the student studied: Classics and French. He proposed that each person has some level of general intelligence, which he called the G Factor, and this construct was meant to capture how quickly students could learn new material, recognize patterns, and think critically, regardless of the subject matter, thus explaining why students’ scores across subjects were correlated.
At around the same time in France, Alfred Binet was tasked with figuring out which kids needed more help in school. Together with Theodore or Simone, he developed the Binet-Simone test, in which students were asked to name what was missing in a drawing, define abstract terms, repeat back sentences, and answer the question of which face was prettiest. Their performance was benchmarked against other students of different ages in order to assign them a mental age. This mental age was then divided by their actual age and multiplied by a hundred to arrive at the so-called intelligence quotient, or IQ.
Spearman and Binet both had the same goal of measuring intelligence, but they used different methods. Spearman used correlations, while Binet used mental age and IQ scores to compare performance. It is known that IQ is a measure of an individual’s G factor in comparison to the rest of the population. 68% of people have an IQ between 85 and 115, while only around 2% score over 130 or under 70.
As I was studying for my IQ test, I practiced all the different types of questions that appear on modern tests. One section almost certainly tests vocabulary, where you are given one word, such as sanguine, and have to pick which of the multiple choice options is most similar in meaning. They might also ask you to pick a word with the opposite meaning - what is the opposite of perspicacious?
Another section tests your ability to spot patterns with numbers. For example, given the sequence 3, 5, 8, 12, what comes next? A good technique is to find the difference between adjacent terms, so in this case the answer is 17. Sometimes the numbers grow rapidly, like in the sequence 3, 15, 60, 180. In cases like this, look at the ratio of one number to the one before it, so the answer should be 360. One of the best known types of IQ test questions are Ravens Progressive Matrices. These involve a three by three grid with symbols in each of the cells and you have to select the ninth cell which follows the pattern. I found that the bulk of these puzzles obey one of only a few different logical rules. One is translational motion, so the symbols move from one cell to the next in a predictable fashion. The second is rotational motion, where one or several objects rotate from one cell to the next. The third is missing symbols, where in each row or column each symbol appears once, so to figure out which symbols appear in the final cell, you just have to spot which ones are missing. The fourth is addition, where the first cell plus the second cell equals the third cell; in this case, lines that overlap cancel out but a line plus nothing equals a line.
Most modern IQ tests are completed under time pressure, with around 10 to 30 seconds per question. It has been argued that tests like the SAT, ACT, and GRE are basically IQ tests, correlating with standard IQ tests at around 0.8.
IQ also has predictive power outside of school. One of the most robust findings is that IQ can predict job success, particularly in technical or high complexity jobs. The correlations typically range from 0.2 to 0.6, and the effect is most notable for more complex jobs. The highest effect is for military training; in fact, the U.S. military will not accept anyone with an IQ under 80, and they also limit to 20 the number of recruits with IQs between 81 and 92. During the Vietnam War, in order to increase the pool of applicants, the military relaxed its last requirement. However, they found that those below the threshold were 1.5 to 3 times as likely to fail recruit training, and required between three to nine times as much remedial training. This added so much strain that the military ran more efficiently without the extra recruits; in total, 5478 people recruited under this initiative died at a fatality rate three times higher than ordinary recruits. As a result, the military reinstated their requirements, and today anyone with an IQ less than 80 (about 30 million Americans) would be ineligible to join the military.
Outside the military, IQ seems to play a role in how long you live. In a Scottish study, scientists uncovered IQ tests from kids when they were 11 years old; 65 years later, they checked to see who from the sample was still alive at age 76. On average, for every 15-point increase on the IQ test, one would be 27 percent more likely to still be alive at age 76. A large meta-analysis confirms that people with higher IQs have a lower risk of dying during the time frame investigated in each study.
The last major thing that IQ seems to predict is income. A study shows a clear tendency for income to increase with IQ, and it found a correlation coefficient of 0.3. However, the variance is huge; in fact, the top three earners in this study all had IQs below 100. A large meta-analysis of 31 studies found that the correlation between IQ and income is significant but small (0.21), meaning that only 4.4 percent of the variance in income is explained by IQ. This could be because economically intelligent behavior is not necessarily highly rewarded. The relationship between IQ and net worth is even weaker, with hardly any correlation between the two. This could be because people with higher IQs may not have the same interest in accumulating wealth, or because IQ has a dark history. Henry Goddard used claims that intelligence was inherited and unchangeable to put IQ at the center of the American Eugenics movement. This led to laws being passed in many states to enable forced sterilization of those who failed to meet a certain threshold on an IQ test, which was upheld by the Supreme Court in 1927. Even words that we now use as insults, such as idiots and imbeciles, were once used as scientific terms in Justice Oliver Wendell Holmes’ judgment. He wrote that it is better for all the world if, instead of waiting to execute degenerate offspring for crime or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind. As a result, over 60,000 people were forcibly sterilized in the United States. In fact, these laws served as a model for Nazi Germany, as Hitler himself claimed to be inspired by American eugenicists.
Given this awful history, it is understandable that many people completely disregard IQ today. On the science of intelligence, there are a number of things that early researchers got wrong. One is that IQ is not entirely determined by genetics. Twin studies suggest that, on average across the whole lifespan, heritability and environment are both about 50%. Education can also improve IQ, which means that it is not fixed over a lifetime as initially imagined.
Nowadays, scientists recognize two forms of intelligence: fluid and crystallized. Fluid intelligence is your ability to learn, process information, and solve novel problems, whereas crystallized intelligence involves the knowledge you’ve accumulated over your lifetime. Both types of intelligence increase throughout childhood, but fluid intelligence peaks in early adulthood and then declines, whereas crystallized intelligence remains more stable.
IQ has also been misused to promote the idea of racial differences in intelligence. There is an observed gap between the average IQ of black and white Americans, and articles have been published on the IQs of different nations around the world. Some of these nations are purported to have average IQs below 70, which is the cutoff for intellectual disability. The conclusion that some draw is that there are genetic differences between races or nations in intelligence. However, this is a gross misrepresentation of the data. The problem is that IQ tests don’t necessarily measure what you think they’re measuring, and the proof is that there is a representative sample of white Americans whose average IQ is 70. Ordinary Americans living around 100 years ago experienced an increase in IQ, known as the Flynn effect. This was due to a number of factors, such as improved childhood nutrition and health, better education, and a shift from manual labor to more abstract thinking. It’s argued that culture Fair tests, which assess visual relations, geometric shapes and patterns, don’t take into account ethnobotanical knowledge or training dogs to hunt, which are arguably more important for survival. Additionally, motivation can have a marked impact on IQ scores, with studies showing that greater incentives result in higher scores. The Fluid Intelligence Index was 118. meaningless and they’re just a way of oppressing people and so there’s a lot of debate about where the truth lies in between those two extremes.
IQ is something that not only psychologists, but also the general public, have a love-hate relationship with. It is an objective measure that helps to iron out social biases, and can be used to identify individuals with strong intellectual abilities who may not have been able to demonstrate them otherwise. IQ tests can also be used to detect people who are attempting to fake poor performance. Although IQ is not the most important thing ever, it can be used to help identify those who are gifted and talented, and those who may need more help. There is a lot of debate about the extremes of IQ, and where the truth lies in between them.