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
PROMOTED VIDEO
Arts and Entertainment
The Apprentice candidates Roisin Hogan, Solomon Akhtar, Mark Wright, Bianca Miller, Daniel Lassman
tvReview: But which contestants got the boot?
Arts and Entertainment
Jim Carrey and Jeff Daniels ride again in Dumb and Dumber To
filmReview: Dumb And Dumber To was a really stupid idea
News
people

Jo from Northern Ireland was less than impressed by Russell Brand's attempt to stage a publicity stunt

Sport
Scunthorpe goalkeeper Sam Slocombe (left) is congratulated by winning penalty taker Miguel Llera (right)
football
Life and Style
A woman walks by a pandal art installation entitled 'Mars Mission' with the figure of an astronaut during the Durga Puja festival in Calcutta, India
techHow we’ll investigate the existence of, and maybe move in with, our alien neighbours
Arts and Entertainment
Sir Ian McKellen tempts the Cookie Monster
tvSir Ian McKellen joins the Cookie Monster for a lesson on temptation
News
i100
News
ebooksNow available in paperback
Travel
Tourists bask in the sun beneath the skyscrapers of Dubai
travelBritish embassy uses social media campaign to issue travel advice for festive holiday-makers in UAE
Arts and Entertainment
Jennifer Saunders stars as Miss Windsor, Dennis's hysterical French teacher
filmJennifer Saunders and Kate Moss join David Walliams on set for TV adaptation of The Boy in the Dress
Life and Style
tech
Sport
Nabil Bentaleb (centre) celebrates putting Tottenham ahead
footballTottenham 4 Newcastle 0: Spurs fans dreaming of Wembley final after dominant win
Life and Style
Sebastian Siemiatkowski is the 33-year-old co-founder and CEO of Klarna, which provides a simple way for people to buy things online
tech
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

Ashdown Group: Service Desk Analyst - Application Support - Central London

£30000 - £35000 per annum + Benefits: Ashdown Group: Service Desk Analyst (App...

Ampersand Consulting LLP: 3rd Line Support Engineer (Windows Server, Exchange Server)

£35000 per annum + Benefits: Ampersand Consulting LLP: 3rd Line Support Engine...

Investigo: Finance Analyst

£240 - £275 per day: Investigo: Support the global business through in-depth a...

Ampersand Consulting LLP: Server / Infrastructure Engineer (Exchange, Windows, VMware)

£32000 - £38000 per annum + Bonus and Benefits: Ampersand Consulting LLP: Serv...

Day In a Page

Jeb Bush vs Hillary Clinton: The power dynamics of the two first families

Jeb Bush vs Hillary Clinton

Karen Tumulty explores the power dynamics of the two first families
Stockholm is rivalling Silicon Valley with a hotbed of technology start-ups

Stockholm is rivalling Silicon Valley

The Swedish capital is home to two of the most popular video games in the world, as well as thousands of technology start-ups worth hundreds of millions of pounds – and it's all happened since 2009
Did Japanese workers really get their symbols mixed up and display Santa on a crucifix?

Crucified Santa: Urban myth refuses to die

The story goes that Japanese store workers created a life-size effigy of a smiling "Father Kurisumasu" attached to a facsimile of Our Lord's final instrument of torture
Jennifer Saunders and Kate Moss join David Walliams on set for TV adaptation of The Boy in the Dress

The Boy in the Dress: On set with the stars

Walliams' story about a boy who goes to school in a dress will be shown this Christmas
La Famille Bélier is being touted as this year's Amelie - so why are many in the deaf community outraged by it?

Deaf community outraged by La Famille Bélier

The new film tells the story of a deaf-mute farming family and is being touted as this year's Amelie
10 best high-end laptops

10 best high-end laptops

From lightweight and zippy devices to gaming beasts, we test the latest in top-spec portable computers
Michael Carberry: ‘After such a tough time, I’m not sure I will stay in the game’

Michael Carberry: ‘After such a tough time, I’m not sure I will stay in the game’

The batsman has grown disillusioned after England’s Ashes debacle and allegations linking him to the Pietersen affair
Susie Wolff: A driving force in battle for equality behind the wheel

Susie Wolff: A driving force in battle for equality behind the wheel

The Williams driver has had plenty of doubters, but hopes she will be judged by her ability in the cockpit
Adam Gemili interview: 'No abs Adam' plans to muscle in on Usain Bolt's turf

'No abs Adam' plans to muscle in on Usain Bolt's turf

After a year touched by tragedy, Adam Gemili wants to become the sixth Briton to run a sub-10sec 100m
Calls for a military mental health 'quality mark'

Homeless Veterans campaign

Expert calls for military mental health 'quality mark'
Racton Man: Analysis shows famous skeleton was a 6ft Bronze Age superman

Meet Racton Man

Analysis shows famous skeleton was a 6ft Bronze Age superman
Garden Bridge: St Paul’s adds to £175m project’s troubled waters

Garden Bridge

St Paul’s adds to £175m project’s troubled waters
Stuff your own Christmas mouse ornament: An evening class in taxidermy with a festive feel

Stuff your own Christmas mouse ornament

An evening class in taxidermy with a festive feel
Joint Enterprise: The legal doctrine which critics say has caused hundreds of miscarriages of justice

Joint Enterprise

The legal doctrine which critics say has caused hundreds of miscarriages of justice
Freud and Eros: Love, Lust and Longing at the Freud Museum: Objects of Desire

Freud and Eros

Love, Lust and Longing at the Freud Museum