Intelligence tests and their limitations

What does it really mean to be intelligent? 

I think we all know about IQ tests, but what most people don’t know is just how much controversy there is regarding IQ testing and how valid the results of these tests truly are.

IQ testing has produced some startling results that have even been used as the foundation of scientific racism. And IQ scores are considered a reasonable basis for arrogance and discrimination.

In this article about intelligence tests and their limitations, we’ll look at what they test and what they don’t, and then you can make your own assessment of how much stock you want to put in the concept of intelligence testing.

What is intelligence?

If you were to ask any person on the street or even the sidewalk what intelligence is, I’m sure you’d end up with an array of similar but hardly identical answers.

Some people will say it means good at academia – school smart.

Others will talk about a person’s skills and abilities, while still others will bring up the ability to remember and recall facts and figures.

But for scientists, concepts that are going to be researched and tested need to be more solidly defined.

Intelligence testing history

Intelligence testing started in the late 1800s.

By the early 1900s, the Stanford-Binet intelligence test had been developed, and this was the standard test used for decades. It also introduced the idea of IQ or intelligence quotient.

It was called a quotient because a person’s mental age was calculated through tests, and this was divided by their real age and then multiplied by 100. 

So if you scored a mental age of 24 on the test, but you were only 12, your IQ would be 200. 

If your mental age was 20, but you were 40 years old, your IQ would be only 50.

However, “mental age” didn’t make much sense as a concept. In order for a person’s IQ to stay constant as they age, they’d have to get way smarter every year!

Through the 20th century, tests were developed to assess people’s intelligence based on a bell curve distribution. Now, scores are adjusted so that 2/3 of people taking the test should fall between 85 and 115 on an IQ test.

But what do these tests really check for?

The g factor

Psychologists found that their measures of IQ were related to other things like general academic performance. They saw that students who did well on intelligence tests also had high grades in school.

Therefore, they decided to call the concept they were testing for “general intelligence” or the “g factor.”

OK, but what is general intelligence?

Fluid intelligence

G was broken down into two further parts, the first being fluid intelligence.

This is the type of intelligence that allows people to think on their feet, find patterns, and solve problems using induction and reasoning.

In essence, this type of intelligence flows into many different applications without the person having to learn anything first, like facts or figures.

Crystallized intelligence

The other part of the g factor was termed crystallized intelligence.

This represented the things that a person learned and memorized and also their ability to recall facts on demand.

These two parts of g were still considered too broad, and later researchers broke them into more parts like verbal comprehension, word fluency, numeracy, visualization, associative memory, speed of perception, reasoning, induction, and more.

The Weschler test uses ten different measures which combine into a single IQ score and this test is most widely used today.

Limits of intelligence testing

youre intelligent according to Intelligence tests and their limitations

Academic skills focus

One of the biggest limits of intelligence testing is the way that IQ tests are focused on academic skills like reasoning and problem-solving. 

While there is a reasonable correlation between things like academic success (0.5) and educational attainment (0.55), this focus on academic intelligence does two things.

First, it ignores skills and abilities that also require intelligence

A carpenter might be excellent at estimating how much wood to use in a project and at making precise cuts, but these skills wouldn’t improve her IQ score.

Second, factors like social or emotional intelligence can’t be measured on these scales. 

A person might be a master at navigating social situations and relating to others, but this wouldn’t help him on an IQ test.

So, we end up with a limited picture of what intelligence is.

Change over time

The Flynn Effect was noticed by a researcher in the mid-1900s.  

IQ scores are always standardized so that 2/3 of people fall in the range of 85-115. This means that no matter what the raw scores are, 100 is always an average IQ.

But after decades of testing, it was found that people’s raw scores were actually going up at a rate of about 2.9 points every decade. This means that in real terms, people today should score almost ten points higher than people 30 years ago.

What could cause this?

While tests have been relatively stable, changes in education, nutrition, lifestyle, and technology have all changed over time in developed countries.

These changes seem to push IQ scores up, while in developing countries, scores have stayed relatively constant.

Scientific racism

The Flynn Effect shows the effects of factors like nutrition, stability, and education on increasing IQs.

But in the past, people didn’t know about these factors, and it was easy to point to certain populations who received low test scores and suggest that some races were intellectually inferior.

While these theories have been completely disproven, the legacy of segregated schools and institutional racism they motivated remain contributing factors in keeping some populations’ scores low.

Final words

Intelligence tests have plenty of limitations, starting with a definition of intelligence that’s not fully agreed upon.

They lean toward academic intelligence and ignore things like physical and interpersonal skills, and IQ scores change over time as the lifestyles of whole populations change.

While intelligence tests can predict some future success, they also miss out on a lot of what makes humans smart.

Marcel Deer

Marcel Deer

Marcel is a journalist, gamer, and entrepreneur. When not obsessing over his man cave or the latest tech, he’s failing helplessly at training his obnoxious rescue dog ‘Boogies’.

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