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: ICT Infrastructure Manager

£27000 - £30000 per annum: Recruitment Genius: This Edinburgh city centre scho...

Recruitment Genius: Massage Therapist / Sports Therapist / Physio / Osteopath

£12000 - £24000 per annum: Recruitment Genius: An opportunity has arisen for o...

Recruitment Genius: Account Manager / Sales Executive - Contract Hire

£35000 - £60000 per annum: Recruitment Genius: This industry leader provides c...

Recruitment Genius: Project Coordinator

£28000 - £30000 per annum: Recruitment Genius: A Project Coordinator is requir...

Day In a Page

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
UK heatwave: Temperature reaches 39.8 degrees on Central Line - the sweatiest place in London

39.8 degrees recorded on Tube

There's hot (London) and too damn hot (the Underground). Simon Usborne braved the Central line to discover what its passengers suffer
Kitchens go hi-tech: From robot chefs to recipe-shopping apps, computerised cooking is coming

Computerised cooking is coming

From apps that automatically make shopping lists from your recipe books to smart ovens and robot chefs, Kevin Maney rounds up innovations to make your mouth water
Jessie Cave interview: The Harry Potter star has published a feminist collection of cartoons

Jessie Cave's feminist cartoons

The Harry Potter star tells Alice Jones how a one-night stand changed her life
Football Beyond Borders: Even the most distruptive pupils score at homework club

Education: Football Beyond Borders

Add football to an after-school homework club, and even the naughtiest boys can score
10 best barbecue books

Fire up the barbie: 10 best barbecue books

We've got Bibles to get you grilling and smoking like a true south American pro
Wimbledon 2015: Nick Bollettieri - Junk balls and chop and slice are only way 5ft 1in Kurumi Nara can live with Petra Kvitova’s power

Nick Bollettieri's Wimbledon Files

Junk balls and chop and slice are only way 5ft 1in Kurumi Nara can live with Petra Kvitova’s power
Ron Dennis exclusive: ‘This is one of the best McLaren teams ever – we are going to do it’

‘This is one of the best McLaren teams ever – we are going to do it’

Ron Dennis shrugs off a poor start to the season in an exclusive interview, and says the glory days will come back
Seifeddine Rezgui: What motivated a shy student to kill 38 holidaymakers in Tunisia?

Making of a killer

What motivated a shy student to kill 38 holidaymakers in Tunisia?
UK Heatwave: Temperatures on the tube are going to exceed the legal limit for transporting cattle

Just when you thought your commute couldn't get any worse...

Heatwave will see temperatures on the Tube exceed legal limit for transporting cattle
Exclusive - The Real Stories of Migrant Britain: Swapping Bucharest for London

The Real Stories of Migrant Britain

Meet the man who swapped Romania for the UK in a bid to provide for his family, only to discover that the home he left behind wasn't quite what it seemed
Cheaper energy on the way, but it's not all sunshine and rainbows

Cheaper energy on the way, but it's not all sunshine and rainbows

Solar power will help bring down electricity prices over the next five years, according to a new report. But it’s cheap imports of ‘dirty power’ that will lower them the most