A Complete Guide to Understanding IQ Test History & Its Uses

The history of IQ tests can be traced back to the 19th century when psychologists first took an interest in measuring traits and intelligence. As a result, they created a new field of study called psychometrics, which rapidly developed throughout the 20th century.

To better understand the history of IQ tests and how they changed in the past century, we’ve consulted our IQ experts and asked them to share the story of how the intelligence quotient came to be, who played the key role in its development, as well as some of the darker aspects of its history.

Let’s review what they’ve told us.

Key Takeaways

• The first IQ test in history was developed in 1904 by French psychologist Alfred Binet, who wanted to assess schoolchildren’s intelligence levels.
• Alfred Binet was inspired by Francis Galton, who first attempted to categorize people based on intelligence and traits.
• Binet’s first IQ test was followed by many others, the most important being the Stanford-Binet and the Wechsler Adult Intelligence Scale.
• IQ testing has numerous applications—for example, academic placement, criminal defense, research, and improving cognition.

IQ Test Predecessors

The predecessors to IQ tests started appearing in the 19th century when interest in intelligence first picked up.

In fact, we can trace it all back to Francis Galton, a British anthropologist known as the father of psychometrics, who first attempted to measure differences in intelligence and personality traits.

Galton was largely inspired by Charles Darwin’s categorizations of animals and plants, believing that a similar classification approach could be applied to humans. As a result, he wrote Hereditary Genius in 1869, a book that details his largely eugenic beliefs and delves into his early findings.

Despite his questionable ideology, Galton was one of the first scientists to propose that intelligence might be hereditary, which is a widely accepted idea today.

He also believed it could be tested using sensorimotor tasks, which require the brain to receive and process a message as well as to produce a response.

Ultimately, Galton’s methods might have been fairly primitive, but they inspired other scientists, such as James McKeen Cattell, to formulate their own theories. In fact, in Cattell’s case, Galton’s influence was strong enough to motivate him to develop a series of mental tests—direct predecessors to the actual IQ tests.

IQ Test History: Alfred Binet and the First IQ Test

IQ Test History: Alfred Binet and the First IQ Test

Galton inspired yet another psychologist to measure intelligence—Alfred Binet, the father of the IQ test. Initially pursuing a law career, Binet got so curious about Galton’s research that he completely shifted focus and began his own experiments.

Then, in 1904, education became mandatory in France, prompting children of all backgrounds to start attending school. Anticipating that some children might require more help than others, the government asked Alfred Binet to find a way to identify them.

And that’s why the first IQ test was created. That same year, Alfred Binet and his colleague, psychologist Theodore Simon, developed a test with 30 questions that measured memory, attention, problem-solving skills, and other cognitive abilities. This first IQ test in history was known as the Binet-Simon Scale.

Once the testing started, Binet realized that some children were far more advanced than others. Based on this observation, he developed the concept of mental age, which was used to calculate the intelligence quotient (IQ) for many years.

The Limitations of the First IQ Test

Since psychometrics, and especially intelligence measuring, was in its infancy, early IQ tests were bound to have certain limitations. Binet’s IQ test was no exception, and he recognized that fact himself.

For instance, Binet was well aware that intelligence was too complex and broad of a concept to measure using a single psychometric tool. He didn’t know how to account for this complexity, so his test was somewhat incomplete.

Moreover, Binet believed intelligence could only truly be compared in children with the same backgrounds. Otherwise, too many factors were at play to allow for an accurate measurement.

Despite its limitations and incompleteness, Binet’s original test was an important milestone in the history of IQ tests which provided a basis for later psychologists to build upon and develop far more precise testing methods.

Henry Goddard’s IQ Test

Binet’s influence crossed French borders and seeped into America even before his IQ test was officially translated. One of the first psychologists who introduced the American public to intelligence testing was Henry Goddard, a well-known eugenicist and segregationist.

In 1908, Goddard published his own version of Binet’s test in America and started advocating for its use in hospitals, schools, and the military. He believed that people with particularly low IQs shouldn’t be allowed to reproduce and should be institutionalized and thus removed from society.

Although his ideas may seem extreme today, they were quite widespread among psychologists and psychometricians at the time. Unfortunately, the dark history of IQ tests can’t be ignored despite all the benefits intelligence testing has brought us.

Understanding the Stanford-Binet Intelligence Scale

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The Stanford-Binet Intelligence Scale is the oldest IQ test currently in use, and it was translated and adapted from the original Binet-Simon Scale by Stanford psychologist and professor Lewis Terman.

In 1916, interest in measuring intelligence was at an all-time high, so Terman used this opportunity to introduce Binet’s test to the American public. However, his adapted test slightly differed from the original—specifically, it used two measurement scales instead of just one.

In addition, it introduced the concept of the intelligence quotient, a single number used to represent the development of cognitive abilities. Binet himself didn’t believe it was possible to express intelligence using just one number, but his idea of mental age became the basis for calculating IQ.

For instance, IQ was initially calculated by dividing a person’s mental age by their actual age and multiplying the result by 100. So, if a 10-year-old child had a mental age of 11, their IQ would be 11 / 10 x 100 = 110.

Of course, the original Stanford-Binet went through numerous revisions over the years, and the concept of mental age is no longer used to calculate IQ.

The Wechsler Intelligence Scales

Stanford-Binet may be the oldest widely used IQ test, but the most popular one is, without a doubt, the Wechsler Adult Intelligence Scale (WAIS). This test was first developed in 1955 by American psychologist David Wechsler, who disagreed with certain aspects of Binet’s test.

For instance, he didn’t like that Stanford-Binet used a single score to represent intelligence as a whole and disagreed with the use of timed tasks. As a result, he first created the Wechsler-Bellevue Intelligence Scale in 1939.

The WAIS came as an improvement upon his first test. Over the years, it went through several editions, and today, it includes both timed tasks and a single IQ score, directly contradicting Wechsler’s initial wishes.

It’s important to note that the WAIS is primarily administered to adolescents and adults, just as its name implies. Children between the ages of 6 and 16 can use the Wechsler Intelligence Scale for Children to determine their IQ score—a version of Wechsler’s original test made with the younger population in mind.

IQ Test Controversies

IQ testing isn’t without its controversies—for one, its unfortunate history with firm ties to eugenics is impossible to ignore. Psychologists such as Francis Galton and Henry Goddard have significantly contributed to the development of IQ tests, and yet they believed only people of certain intelligence deserved to participate in society.

Though such ideas are nowhere near as widespread today, they still do exist, and their proponents still believe that IQ tests make perfect tools for building a society composed only of those with acceptable intelligence.

In addition, there are several other controversies related to IQ testing:

• Reliability of IQ tests. IQ tests are somewhat flawed because they can’t measure your intelligence with complete objectivity. Although they come close, a lot still depends on your mood, physical and mental condition, and level of preparedness.
• Slight cultural bias. Even the tests that attempt to be fully culture-neutral and include no language, like Raven’s Progressive Matrices, can’t entirely escape cultural bias. That’s because IQ tests naturally favor those who receive formal education or subscribe to the Western way of thinking.
• Only specific kinds of intelligence count. According to Gardner’s theory of multiple intelligences, every person possesses nine kinds of intelligence to a varying degree, and most IQ tests only measure two—logical-mathematical and verbal-linguistic intelligence. They don’t account for the others, which can be equally important.

What Are IQ Tests Used For?

IQ tests are used for educational placement, research, criminal defense, and measuring and improving cognitive abilities. Below, we explore each of these applications in more detail.

#1. Educational Placement

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IQ tests are often administered to school-age children to determine whether their cognitive abilities are sufficiently developed. Thanks to that, parents and teachers can decide how to accommodate the child best and use their potential.

For instance, if a child receives an exceptionally high score on an IQ test, they may be advised to skip a grade or attend special programs for gifted children that will nurture their intelligence.

On the other hand, if their IQ is below average, teachers will be aware that the child might need extra help to keep up with the rest of the class. As a result, they can think of an appropriate approach or strategy to help them.

#2. Criminal Defense Applications

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On Henry Goddard’s suggestion, IQ testing was first used in court as evidence in 1914. Today, this is somewhat of a standard practice, especially for criminal defense.

For instance, if an IQ test shows the defendant’s intelligence is particularly low, the court may rule that they can’t be held responsible for their actions. In such a case, the sentence would be reduced accordingly.

Of course, there are certain controversies surrounding this application—namely, many wonder where exactly the line should be drawn. Legislation isn’t particularly precise in this matter, which allows for all kinds of interpretations.

#3. Research Studies

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Psychologists use IQ tests in their studies on human behavior, traits, and other phenomena related to the psyche. Usually, they explore how intelligence impacts certain behaviors, whether it determines specific characteristics, and what factors influence it over a person’s lifetime.

For instance, it’s thanks to IQ tests that we know about the correlation between intelligence and success, as well as the fact that video games can actually boost IQ, contrary to popular beliefs that claim otherwise.

#4. Improving Cognitive Abilities

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Although IQ tests are primarily used to measure intelligence level, they can also serve as excellent tools for exercising and boosting cognition.

For example, IQtest.net, our free IQ test designed by intelligence experts, contains tasks that target and improve cognitive abilities such as working memory, deductive reasoning, critical thinking, and analytical skills.

In addition, the test uses the latest psychometric methods to calculate your IQ score, giving you a simple way to track your progress as you embark on your journey to improve your intelligence.

#5. Job Candidate Selection

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Occasionally, IQ tests are used to help employers select a perfect candidate for a certain position. This is usually done in more mentally challenging fields, as employers need someone with developed cognition and a high potential for learning and growth.

However, using IQ tests in the candidate selection process is somewhat controversial nowadays. Many believe they can be used as a tool of discrimination and that they don’t paint the whole picture anyway. After all, someone may score high on an IQ test and still underperform as an actual employee due to various factors.

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Final Thoughts

Although the history of IQ tests isn’t very long, we can’t deny that they’ve significantly changed how we view and approach intelligence. Before IQ testing, intelligence was a vague, undefinable concept, while now we know how to measure, quantify, and define it.

Even more importantly, we know how to develop its full potential through brain exercises, a healthier lifestyle, learning, and education. As a result, society as a whole is growing more intelligent, which can only benefit us in the long run.