WE all know people who like to think that they are good at multi-tasking.
But a new study suggests that people who multi-task the most are the least able to do so.
Psychologists tested 310 students to compare their "real" and perceived multi-tasking ability. Use of mobile phones while driving was measured, as was a range of personality traits.
Lead researcher Professor David Sanbonmatsu, from the University of Utah, US, said: "Our data suggest the people talking on cell phones while driving are people who probably shouldn't. We showed that people who multi-task the most are those who appear to be the least capable of multi-tasking effectively."
The findings, in the online journal Public Library of Science ONE, showed that the more people talked on mobile phones while driving, or used different forms of media at once, the worse they were at multi-tasking. However, their self-perceived multi-tasking ability was "significantly inflated".
In fact, 70pc of participants thought they were above average, which was statistically impossible. Individuals who really were good at multi-tasking tended not to.
Often, multi-tasking had nothing to do with having a flexible brain but was the result of people being unable to block out distractions and focus on one task at a time.
Those who multi-tasked the most tended to be impulsive, sensation-seeking and overconfident, said the scientists.
The scientists wrote: "The negative relation between cellular communication while driving and multi-tasking ability appears to further bolster arguments for legislation limiting the use of cell phones while operating in a motor vehicle."
Multi-tasking was measured using a test that taxed memory and mathematical ability.