An IQ (intelligence quotient) test is a standardized test specially developed to test an individual's intelligence. Most IQ tests are designed to focus on logic and reasoning ability.
The test is called the intelligence quotient test because the early method used to calculate the results divided a person’s mental age by their chronological age. This value was then multiplied by 100. For example, if a 10-year-old tests at a 10-year-old level, their quotient is 1.0, and their IQ is 100. The scoring method has since changed. You will learn more about it in a few minutes.
History of the IQ Test
Sir Francis Galton and James McKeen Cattell both made early attempts at measuring intelligence. These early forms, developed in 1884 and 1980, were very primitive and inaccurate at measuring reasoning ability. The first IQ test that proved reasonably accurate in measuring intelligence was developed by Alfred Binet in 1905. Historically, Binet created the IQ test to identify children that were falling behind their peers in school.
While Binet developed his IQ test for students in France, an eager teacher, Henry Goddard, translated the test and started administering it to his students. The test quickly spread throughout American public schools.
The Binet IQ test became more widely used when it was revised by Lewis Terman in 1916 and renamed the Stanford-Binet test. The test was more accepted when Terman began multiplying the intelligence quotients by 100. An IQ of 100 seems more intuitive than 1. While this test was also developed for children, almost 2 million soldiers took it during World War I.
Eventually, it became clear that dividing mental age by chronological age did not effectively gauge adult intelligence. To accurately calculate the IQ for adults, David Wechsler set the average adult IQ to an arbitrary 100 points. One standard deviation below or above the average was 15 points lower or higher. This effectively removed ‘quotient’ from the intelligence quotient (IQ) test, but the name was already ubiquitous and stuck. Wechsler's changes to scoring also stuck and are still used today.
Types of IQ Tests
The subject of intelligence has been controversial among psychologists since the early 1900s. Many top psychologists argued on the different types of intelligence, factors affecting a person's intelligence, and the best IQ test methods. As a result, many IQ tests have been developed over the years. Below are some of the most widely used IQ tests:
- Stanford-Binet Intelligence Scale: Historically the most widely used IQ test, developed by Binet and revised by Terman. It measures intelligence but is especially good at identifying learning disabilities.
- Universal Nonverbal Intelligence: Commonly used to test children and adolescents that have impairments in speech or hearing.
- Differential Ability Scales (DAS): Commonly administered in the US to children up to 17 years 11 months old.
- Peabody Individual Achievement Test (PIAT): The test is designed to return a grade level (K through 12) to assess students between the ages of 5 and 22.
- Wechsler Individual Achievement Test (WIAT): Developed by Wechsler to test scholastic achievement between ages of 4 and 85. Tests writing, math, reading, and oral language.
- Wechsler Adult Intelligence Scale (WAIS): Currently, the most widely used IQ test for adults, developed by Wechsler.
- Woodcock-Johnson III Tests of Cognitive Abilities: Popular for testing individuals for giftedness and diagnosing intellectual disabilities.
- Raven’s Progressive Matrices: Developed by John Raven for anyone over 5. The test requires individuals to complete a pattern or identify the missing part of a pattern. It gets progressively harder throughout the 60 question test.
It’s important to select a test that has been designed with the specific test taker in mind. A psychologist can help identify which test is best suited for you, but many of these tests are also available for purchase online.
Any 10-minute free online IQ test is not a recognized or real form of IQ testing. These tests can be fun and even challenging, but without testing and research, the results are likely to be wildly inaccurate.
What is the IQ Test Based On?
As mentioned, the best methods for testing an individual's IQ have been controversial. Most psychologists recognize four major categories of intelligence:
Verbal Intelligence is the comprehension of language and associated skills. Those with average or above-average verbal intelligence will perform well in tests that focus on the ability to form and understand concepts using words. Questions testing verbal intelligence often use reading comprehension, such as a paragraph with associated questions, and vocabulary-based questions.
Careers for those with high verbal intelligence include journalists, lawyers, writers, librarians, and researchers.
Numerical intelligence concerns the ability to understand numerical information and solve associated problems. Those with average or above-average numerical intelligence will perform well on questions that test basic mathematical and quantitative concepts. Questions testing numerical intelligence may involve concepts like even/odd, patterns, percentages, fractions, and more.
Careers for those with high numerical intelligence include mathematicians, statisticians, accountants, computer scientists, and AI/machine learning scientists.
Spatial intelligence is the ability to visualize shapes and transformations within your mind. Those with average or above-average spatial intelligence will perform well in tests focusing on the individual's ability to recognize different perspectives and angles and imagine and track shape transformations. Questions testing spatial intelligence may involve 2D and 3D shapes, shape rotation, and patterns.
Careers for those with high spatial intelligence include architects, graphic designers, interior designers, mechanical engineers, and urban planners.
Logical intelligence is the ability to use reason to analyze situations and solve problems. Those with average or above-average spatial intelligence will perform well on questions involving cause-and-effect, abstract concepts, analysis, and problem-solving. Individuals with logical intelligence also tend to score well on numerical questions.
Careers for those with high logical intelligence include lawyers, scientists, detectives, doctors, and computer programmers.
These four major categories are the basis for question formation in the most popular IQ tests. Often two types of intelligence are combined into one question, e.g., mathematical word problems test both verbal and numerical intelligence.
Outside of these main categories, there are many other proposed forms of intelligence. Howard Gardner believed there were 9 distinct forms of intelligence, including 5 not mentioned above: musical intelligence, interpersonal intelligence, social intelligence, existential intelligence, and kinesthetic intelligence. Ultimately, the human brain and human intelligence is not a universal phenomenon. As varied as humans are, so too is intelligence.
IQ Test Score Meaning
What is a Good IQ Test Score?
What IQ score signifies an average IQ? A good IQ? And what about a genius IQ? Before answering these questions, you need to understand what the IQ test ranges mean.
As briefly mentioned before, modern IQ tests have placed the average adult IQ at 100. IQ test scores use a normal distribution or Bell Curve. The further away from the mean or peak of the curve, the more unique your score is. A standard deviation of 15 is used, meaning 68% of test-takers will score within 15 points of 100. 50% of the population will score between 90-110 on an IQ test. 15% will score between 111-120, while another 15% will score between 80-89.
IQ Score ranges can be broken down as follows:
- Very Gifted — 130 or above
- Gifted — 121 to 130
- Above-average intelligence — 111 to 120
- Average intelligence — 90 to 110
- Below average intelligence — 80 to 89
- Cognitively impaired — 70 to 79
A genius IQ score is assigned to individuals with a score over 160. Less than 0.25% of the population falls in this category. While Albert Einstein never took an IQ test, researchers believe his IQ was approximately 160.
Highest IQ Test Score Ever
Marilyn Vos Savant received the highest IQ ever recorded at 228. Marilyn took the Stanford-Binet IQ test in 1956 at 10 years old. Her family kept her results secret after Marilyn took the Stanford-Binet IQ test in 1956 at 10 years old until The Guinness Book of Records learned of her scores in 1985. Researchers now believe the psychologist improperly scored her test. Although she is incredibly intelligent, 228 is off the charts.
Problems with IQ Testing
Recently, the problematic history of IQ testing has been brought into the light. Many prominent psychologists involved in creating and revising IQ testing methods also held some problematic and immoral stances concerning intelligence. While the initial purpose behind IQ tests was ethical, eventually, they were used immorally.
Eugenicists like Lewis Terman and Henry Goddard argued that those with low IQs should not be allowed to procreate. They felt that they should be institutionalized or forcibly sterilized by society to prevent low intelligence from spreading. Racists and ethnocentrists tried to manipulate IQ data to argue that ethnic minorities had lower IQs because of their race. IQ tests were used to support their beliefs that evolutionary differences and inferiority existed.
Now IQ tests are once again largely used for moral and upstanding reasons. Psychologists, social workers, and other professionals administer IQ tests to help provide early intervention for students with learning disabilities or to diagnose severe mental disabilities. IQ tests can also identify gifted students and allow school systems to provide proper support and advanced classes.
Psychologists have historically argued about the validity and reliability of IQ testing. Intelligence is fluid, and humans are learning new concepts and skills every day. Some psychologists believe that IQ tests cannot be universally applied because of different cultural differences that could lead to differences in specific skills.
Ultimately, modern IQ tests have been extensively studied and tested. The tests are regularly revised based on statistical information. Researchers identify questions that are unfair and better sculpt them for the general public. IQ tests are based on statistical models. Every few years, they are recalibrated because of psychologist and philosopher Jim Flynn’s findings on the increase in the average IQ over the years.
How to Boost Your IQ Test Score
You may want to know how to improve or boost your IQ test scores. A high IQ can provide a major sense of pride, even if kept to oneself. There are many resources on the internet that offer advice on how to get a high IQ test score. A natural approach to improving intelligence works best. To improve your skills in the four major categories:
- Learn new languages
- Daily reading of fiction and non-fiction
- Memory exercises
- Learn a musical instrument
- Spatial and logic puzzles
- Learn chess
- Exercise and sleep well
If you have spent some time with these activities and working on verbal, spatial, numerical, and logical skills, you may be ready to take an IQ test and see where you fall!