Humans cannot multitask (even women)

Study finds the structure of the brain means we struggle to do more than two jobs at once

The human mind may be inherently incapable of dealing with more than two tasks at a time according to a study showing that "multi-tasking" skills are limited by the physical division of the brain into two hemispheres.

Scientists have found that when people have to carry out two tasks simultaneously their brains divide each job up so that one is performed largely by the left side of the brain and the other is carried out mainly on the right.

The study suggests that this basic division of the brain into two halves may explain why human beings tend to prefer a simple choice between two options rather than three or more. It might even explain why the Liberal Democrats, as the third political party, find it hard to get a look in at general elections.

Sylvain Charron and Etienne Koechlin of France's National Institute of Health and Medical Research in Paris, discovered the way the brain divides up two simultaneous tasks. They asked 32 volunteers to carry out two different mental puzzles while their brains were being scanned by an MRI machine.

"Each subject was performing two tasks concurrently. One task was to pair upper case letters and the other task was to pair lower case letters together. It was a very simple task and the subjects had to switch back and forth between them," Dr Koechlin said.

"We motivated them with a reward if they made no errors between trials. It was a monetary reward actually, so when the subject made an error on one of the tasks, their reward was less. We rewarded brain activity and at the same time we monitored the subjects' errors, reaction time and so on. So we could measure performance and we found that a larger reward was associated with a better performance," he said.

The study, published in the journal Science, focused on the medial frontal cortex, which lies at the front of the brain above the eyes. It is this part of the brain that is thought to drive the pursuit of rewards associated with carrying out a task. The medial frontal cortex is divided into two halves, one for each side of the brain, and the scientists found when they monitored a subject's brain activity in the MRI scanner that the right side of the frontal cortex tended to be active when the subject was carrying out one task, and the left side was more active when carrying out the other.

All volunteers were right-handed so there was no confusion about which part of the brain was controlling each task – the right hand is controlled by the left side of the brain and vice versa.

"We found that brain activity increased with rewards and expectations in the medial frontal cortex. We found in the left hemisphere that the activity increased as the reward value of one task increased, but not the other task, whereas in the right hemisphere the brain activation was related to the reward value of the other task," Professor Koechlin said.

"The two hemispheres co-operated when there was only one task. But in two tasks, one hemisphere covers the reward of one task and the other hemisphere covers the reward of the other."

"The human prefrontal function seems to be built to control two tasks simultaneously. It means in everyday behaviour we can readily switch between two tasks but not between three. With three tasks the division is limited to only two hemispheres, so there is a problem," he said.

This physical restraint on doing three things at once may have wider implications for human reasoning. "We know that subjects have difficulty deciding between more than two options and our study provides a possible explanation for why we like such binary decisions – because the brain's frontal lobe function is fundamentally binary in nature," Professor Koechlin said.

And, contrary to popular belief, they found no differences in multi-tasking skills between the sexes, meaning no excuses for men from now on.

Start your day with The Independent, sign up for daily news emails
New Articles
tvDownton Abbey Christmas special
Arts and Entertainment
Wolf (Nathan McMullen), Ian (Dan Starky), The Doctor (Peter Capaldi), Clara (Jenna Coleman), Santa Claus (Nick Frost) in the Doctor Who Christmas Special (BBC/Photographer: David Venni)
tvOur review of the Doctor Who Christmas Special
News
peopleIt seems you can't silence Katie Hopkins, even on Christmas Day...
News
news
PROMOTED VIDEO
News
i100
Arts and Entertainment
Left to right: Stanley Tucci, Sophie Grabol and Christopher Eccleston in ‘Fortitude’
tvSo Sky Atlantic arrived in Iceland to film their new and supposedly snow-bound series 'Fortitude'...
Arts and Entertainment
Jenna Coleman as Clara Oswald in the Doctor Who Christmas special
tvForget the rumours that Clara Oswald would be quitting the Tardis
Arts and Entertainment
Japanese artist Megumi Igarashi showing a small mascot shaped like a vagina
art
News
The Queen delivers her Christmas message
newsTwitter reacts to Her Majesty's Christmas Message
Arts and Entertainment
tv
Life and Style
fashion
ebooks
ebooksA year of political gossip, levity and intrigue from the sharpest pen in Westminster
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: Marketing Manager/Marketing Controller (Financial Services)

£70000 - £75000 per annum + benefits: Ashdown Group: Marketing Manager/Marketi...

Recruitment Genius: Account Manager

£20000 - £35000 per annum: Recruitment Genius: This full service social media ...

Recruitment Genius: Data Analyst - Online Marketing

£24000 - £35000 per annum: Recruitment Genius: We are 'Changemakers in retail'...

Austen Lloyd: Senior Residential Conveyancer

Very Competitive: Austen Lloyd: Senior Conveyancer - South West We are see...

Day In a Page

A Christmas without hope: Fears grow in Gaza that the conflict with Israel will soon reignite

Christmas without hope

Gaza fears grow that conflict with Israel will soon reignite
After 150 years, you can finally visit the grisliest museum in the country

The 'Black Museum'

After 150 years, you can finally visit Britain's grisliest museum
No ho-ho-hos with Nick Frost's badass Santa

No ho-ho-hos with Nick Frost's badass Santa

Doctor Who Christmas Special TV review
Chilly Christmas: Swimmers take festive dip for charity

Chilly Christmas

Swimmers dive into freezing British waters for charity
Veterans' hostel 'overwhelmed by kindness' for festive dinner

Homeless Veterans appeal

In 2010, Sgt Gary Jamieson stepped on an IED in Afghanistan and lost his legs and an arm. He reveals what, and who, helped him to make a remarkable recovery
Isis in Iraq: Yazidi girls killing themselves to escape rape and imprisonment by militants

'Jilan killed herself in the bathroom. She cut her wrists and hanged herself'

Yazidi girls killing themselves to escape rape and imprisonment
Ed Balls interview: 'If I think about the deficit when I'm playing the piano, it all goes wrong'

Ed Balls interview

'If I think about the deficit when I'm playing the piano, it all goes wrong'
He's behind you, dude!

US stars in UK panto

From David Hasselhoff to Jerry Hall
Grace Dent's Christmas Quiz: What are you – a festive curmudgeon or top of the tree?

Grace Dent's Christmas Quiz

What are you – a festive curmudgeon or top of the tree?
Nasa planning to build cloud cities in airships above Venus

Nasa planning to build cloud cities in airships above Venus

Planet’s surface is inhospitable to humans but 30 miles above it is almost perfect
Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

Clocks, rifles, swords, frogmen’s uniforms

Surrounded by high-rise flats is a little house filled with Lebanon’s history
Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

Four months after the bombardment, Gaza’s wounds are yet to heal

Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
Gastric surgery: Is it really the answer to the UK's obesity epidemic?

Is gastric surgery really the answer to the UK's obesity epidemic?

Critics argue that it’s crazy to operate on healthy people just to stop them eating
Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

Homeless Veterans appeal: Christmas charity auction

Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
Pantomime rings the changes to welcome autistic theatre-goers

Autism-friendly theatre

Pantomime leads the pack in quest to welcome all