IQ tests are 'fundamentally flawed' and using them alone to measure intelligence is a 'fallacy', study finds

Results cast into doubt tests that have been used to link cognitive ability to race, gender and class

The idea that intelligence can be measured by IQ tests alone is a fallacy according to the largest single study into human cognition which found that it comprises of at least three distinct mental traits.

IQ tests have been used for decades to assess intelligence but they are fundamentally flawed because they do not take into account the complex nature of the human intellect and its different components, the study found.

The results question the validity of controversial studies of intelligence based on IQ tests which have drawn links between intellectual ability race, gender and social class and led to highly contentious claims that some groups of people are inherently less intelligent that other groups.

Instead of a general measure of intelligence epitomised by the intelligence quotient (IQ), intellectual ability consists of short-term memory, reasoning and verbal agility. Although these interact with one another they are handled by three distinct nerve “circuits” in the brain, the scientists found.

“The results disprove once and for all the idea that a single measure of intelligence, such as IQ, is enough to capture all of the differences in cognitive ability that we see between people,” said Roger Highfield, director of external affairs at the Science Museum in London.

“Instead, several different circuits contribute to intelligence, each with its own unique capacity. A person may well be good in one of these areas, but they are just as likely to be bad in the other two,” said Dr Highfield, a co-author of the study published in the journal Neuron.

The research involved an on-line survey of more than 100,000 people from around the world who were asked to complete 12 mental tests for measuring different aspects of cognitive ability, such as memory, reasoning, attention and planning.

The researchers took a representative sample of 46,000 people and analysed how they performed. They found there were three distinct components to cognitive ability: short-term memory, reasoning and a verbal component.

Professor Adrian Owen of the University of Western Ontario in Canada said that the uptake for the tests was astonishing. The scientists expected a few hundred volunteers to spend the half hour it took to complete the on-line tests, but in the end they got thousands from every corner of the world, Professor Owen said.

The scientists found that no single component, or IQ, could explain all the variations revealed by the tests. The researcher then analysed the brain circuitry of 16 participants with a hospital MRI scanner and found that the three separate components corresponded to three distinct patterns of neural activity in the brain.

“It has always seemed to be odd that we like to call the human brain the most complex known object in the Universe, yet many of us are still prepared to accept that we can measure brain function by doing a few so-called IQ tests,” Dr Highfield said.

“For a century or more many people have thought that we can distinguish between people, or indeed populations, based on the idea of general intelligence which is often talked about in terms of a single number: IQ. We have shown here that’s just wrong,” he said.

Studies over the past 50 years based on IQ tests have suggested that there could be inherent differences in intelligence between racial groups, social classes and between men and women, but these conclusions are undermined by the latest findings, Dr Highfield said.

“We already know that, from a scientific point of view, the notion of race is meaningless. Genetic differences do not map on to traditional measurements of skin colour, hair type, body proportions and skull measurements. Now we have shown that IQ is meaningless too,” Dr Highfield said.

The smarter test: Try it yourself

These questions evaluate the three components of intelligence.

Memory

Candidates would be asked to remember and repeat a sequence, digits 3, 6, 1, 9, 6, 2, 5, 3 for example

Reasoning

If Box A is twice as big as Box B and Box C is half the size of Box A, which is bigger, C or B?

Verbal skills

If you are given the statement, “A does not follow B”, and then shown the letter B followed by the letter A, is the statement true or false?

Answers: They’re both the same size; False

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Cleaner

£15000 - £16500 per annum: Recruitment Genius: If you've got first class custo...

Recruitment Genius: Mobile Applications Developer / Architect - iOS and Android

Negotiable: Recruitment Genius: This is a great opportunity to join a medium s...

Recruitment Genius: Telesales Account Executive - £40K OTE

£11830 - £40000 per annum: Recruitment Genius: Working in a friendly, sales ta...

Recruitment Genius: Web Designer

£15000 - £27000 per annum: Recruitment Genius: One of the UK's leading web des...

Day In a Page

Greece debt crisis: What happened to democracy when it’s a case of 'Vote Yes or else'?

'The economic collapse has happened. What is at risk now is democracy...'

If it doesn’t work in Europe, how is it supposed to work in India or the Middle East, asks Robert Fisk
The science of swearing: What lies behind the use of four-letter words?

The science of swearing

What lies behind the use of four-letter words?
The Real Stories of Migrant Britain: Clive fled from Zimbabwe - now it won't have him back

The Real Stories of Migrant Britain

Clive fled from Zimbabwe - now it won’t have him back
Africa on the menu: Three foodie friends want to popularise dishes from the continent

Africa on the menu

Three foodie friends want to popularise dishes from the hot new continent
Donna Karan is stepping down after 30 years - so who will fill the DKNY creator's boots?

Who will fill Donna Karan's boots?

The designer is stepping down as Chief Designer of DKNY after 30 years. Alexander Fury looks back at the career of 'America's Chanel'
10 best statement lightbulbs

10 best statement lightbulbs

Dare to bare with some out-of-the-ordinary illumination
Wimbledon 2015: Heather Watson - 'I had Serena's poster on my wall – now I'm playing her'

Heather Watson: 'I had Serena's poster on my wall – now I'm playing her'

Briton pumped up for dream meeting with world No 1
Wimbledon 2015: Nick Bollettieri - It's time for big John Isner to produce the goods to go with his thumping serve

Nick Bollettieri's Wimbledon Files

It's time for big John Isner to produce the goods to go with his thumping serve
Dustin Brown: Who is the tennis player who knocked Rafael Nadal out of Wimbeldon 2015?

Dustin Brown

Who is the German player that knocked Nadal out of Wimbeldon 2015?
Ashes 2015: Damien Martyn - 'England are fired up again, just like in 2005...'

Damien Martyn: 'England are fired up again, just like in 2005...'

Australian veteran of that Ashes series, believes the hosts' may become unstoppable if they win the first Test
Tour de France 2015: Twins Simon and Adam Yates have a mountain to climb during Tour of duty

Twins have a mountain to climb during Tour of duty

Yates brothers will target the steepest sections in bid to win a stage in France
John Palmer: 'Goldfinger' of British crime was murdered, say police

Murder of the Brink’s-MAT mastermind

'Goldfinger' of British crime's life ended in a blaze of bullets, say police
Forget little green men - aliens will look like humans, says Cambridge University evolution expert

Forget little green men

Leading evolutionary biologist says aliens will look like humans
The Real Stories of Migrant Britain: An Algerian scientist adjusts to life working in a kebab shop

The Real Stories of Migrant Britain

An Algerian scientist struggles to adjust to her new life working in a Scottish kebab shop
Bodyworlds museum: Dr Gunther von Hagens has battled legal threats, Parkinson's disease, and the threat of bankruptcy

Dying dream of Doctor Death

Dr Gunther von Hagens has battled legal threats, Parkinson's disease, and the threat of bankruptcy