The Myth of Multitasking

The discovery in 2007 of a 'bottleneck in the brain' finally confirmed what many men had suspected for a long time, namely that no one — not even a woman — can do two things at once! The myth of multitasking was laid to rest.

Writing in the New Scientist, in April 2007, Alison Metlock reported David Strayer's finding that talk/drive should become the new drink/drive, for all drivers, male and female. The problems caused by talking and driving include an impaired reaction time, and hands-free sets for phones do not improve this. In 2005, in the UK, 13 people were killed and 400 seriously injured by drivers who thought that they could talk and drive. The equivalent figures for the US were 2,600 dead and 330,000 injured.

Researchers at the Institute of Psychiatry at King's College London asked two sets of subjects to take IQ tests. One group had to check e-mails and respond to instant messages while taking the test. The second group just sat down and did the test without distractions.

The distracted scored 10 points lower than the control group. In similar testing conditions, people intoxicated by marijuana scored 8 points lower. So researchers drew attention to their study by noting that multitasking is worse for your ability to concentrate than getting stoned.

Rene Marois thinks that self-styled multitaskers are simply underperformers of parallel tasks. You can get better at parallel processing, which in reality involves rapid alternation between parallel tasks, but the evidence says 'one thing at a time' is best for optimum performance.

The problem, even for those who practiced (twice a minute for an hour a day for 14 days) was that doing even just two tasks, both very simple, involves negotiating three bottlenecks in your brain, write Horne and Wootton in their book Training Your Brain:

• Deciding to what to give your attention. This is called the 'Attention Blink'.
• Holding two sets of information in a short-term memory that is already limited. This is called the 'Cognitive Limit'.
• Selecting a response to each situation and then deciding which selection to implement first causes a further delay. This is called the 'Selection Blink'.