I'VE never thought of myself as particularly distractable, but today the evidence seems to suggest otherwise. While wondering how to start this article I have: 1) opened an email alert telling me I have spam; 2) stared at a colleague's new haircut; and 3) watched a cloud shaped like a cow turn into a sad face, and wondered if it meant anything. Getting down to work is proving to be rather a struggle.

I'VE never thought of myself as particularly distractable, but today the evidence seems to suggest otherwise. While wondering how to start this article I have: 1) opened an email alert telling me I have spam; 2) stared at a colleague's new haircut; and 3) watched a cloud shaped like a cow turn into a sad face, and wondered if it meant anything. Getting down to work is proving to be rather a struggle.

Wandering attention is an occupational hazard for the average office worker; research suggests that interruptions can take up to 2 hours out of the working day (New Scientist, 28 June 2006, p 46). Of the many things that disrupt our flow, visual distractions, like email notifications, flashing telephone message lights or people walking past the window, are among the most difficult to ignore. In the office these kinds of distractions are annoying, but for pilots, air traffic controllers and truck drivers - occupations where there are many visual distractions - they can be downright dangerous. A study of drivers by the US National Highway Traffic Safety Administration last year showed that glancing away from the road for more than 2 seconds doubles the risk of a crash or near-miss.

Clearly some people are better at concentrating through these kinds of distractions than others, but until recently there was no easy way to quantify someone's visual distractability, or to reliably compare different people, and so no way to tell whether someone would make an excellent air traffic controller, or would be better suited to another role. Thanks to a simple computer test devised by psychologist Nilli Lavie and her colleagues at University College London (UCL) that has all changed. Using their test it is, for the first time, possible to obtain an objective measure of an individual's ability to concentrate in the face of a visual distraction. Surprisingly, it also suggests that the way to keep people's minds on the job could be to make workstations more visually challenging, not simpler.

If eye-catching distractions sometimes seem impossible to ignore, that's probably because they are. Psychologist Jan Theeuwes at the Free University in Amsterdam tracked people's eye movements during experiments in which they were asked to concentrate on one coloured shape while ignoring shapes of other colours. No matter how hard they tried, people couldn't stop their eyes from wandering to the shape they were trying to ignore, Theeuwes found (Psychological Science, vol 9, p 379). "It seems automatic," he says. "The visual system takes over and selects things for us that we're not even looking for."

The distraction needn't be right in front of you: it could be a lurid advertisement at the roadside or a fly hovering around you that grabs your attention. "You don't have voluntary control - you can't say 'stop' to a distracter," Lavie says. "If you wish to ignore something, that doesn't mean that you will succeed."

Before Lavie's test came along, most researchers investigating distractability used the cognitive failures questionnaire (CFQ), developed by University of Oxford psychologist Donald Broadbent in 1982. It asks people to describe how often they get distracted in particular situations, from failing to notice road signs to forgetting to lock their front door. In various studies since then, people with high scores on the questionnaire have been found to suffer fallout from their distractability, ranging from absent-minded injuries to forgetting to save computer files.

As a method of measuring distractability, however, the CFQ has some serious limitations: it relies on people self-reporting their absent-mindedness, which may be unreliable and, more importantly, it is unable to separate distractability from other factors like forgetfulness or poor organisational skills. It also gets us no closer to working out why some people are better at concentrating than others.

Lavie's test gets round these problems. The test takes the form of a simple computer game in which volunteers are asked to concentrate on letters flashing up in a particular area on the screen, and to press one key if they see an N and another if they see an X (see Diagram). Outside this area, other letters pop up as distractions. It measures how much these distractions increase the time it takes to press the correct button and the number of mistakes people make. At the end of the test the program generates an "index of distractability", which corresponds to a measure of a person's powers of concentration.

Forced errors

I give it a go. It's easy at first, but soon irrelevant letters start popping up in my peripheral vision, slowing me down and forcing me to make errors. In her experiments, Lavie found that while distractions slowed everybody's reaction time, some people slowed by nearly twice as much as others (Psychological Science, vol 18, p 377). Some people don't even notice that they have made mistakes, and walk away from the test thinking they have performed well, Lavie says.

When the going gets tough, however, something surprising happens: the difference between the poor concentrators and good concentrators disappears. During more visually intensive tasks, when the area of screen to focus on is more cluttered with letters, most people are able to ignore the distractions.

This suggests there could be a way to trick the brain into paying attention by tapping into the way it focuses its attention. The fact is that even the most inattentive people aren't total slaves to distraction. Being able to focus on the important aspects of the world around us is crucial to nearly everything we do, be it driving a car, watching television, or just walking down the street. Without some kind of underlying sorting mechanism, the world would be a surge of information with no way for us to prioritise the important stuff.

Until recently, psychologists disagreed on how the brain deals with this problem. One camp reckoned that the act of concentration induces your brain to become blinkered to irrelevant distractions, so it won't process them at all. Imagine concentrating on driving: you watch for road signs and hazards while tracking the bend of the road and the car in front. These researchers argued that while doing these tasks your brain is less likely to take note of a billboard at the roadside.

The other camp thought that the minute we open our eyes we perceive everything, and that the brain sorts through what's important after this information has been collected. So back in the driving seat, your brain's visual system would perceive the billboard but would prioritise the information about the upcoming bend in the road.

In 1997 Lavie did a series of experiments which, she says, showed that both camps were wrong. Concentrating in itself is not enough to screen out distractions. Moreover, there is an upper limit to what our eyes can perceive - it can't take in everything at once.

In one of these experiments, she asked people to complete quick-fire word-based tasks on a computer screen while distracting them (Science, vol 278, p 1616). The person's goal was either to decide whether words appearing on a computer screen were upper or lower case, or the trickier task of counting each word's syllables. On the screen's periphery, a simulation of a moving starfield gave the sensation of moving forward or backward through space - a distraction which Lavie asked people to ignore. Using functional MRI, she monitored activity in a part of the brain called V5, in the visual cortex, which becomes active when we experience such sensations of movement.

The results were surprising. During the simple word puzzles, V5 was active despite people consciously attempting to ignore the starfield. There goes one side of the attention debate: it would appear that you can't always filter out distractions simply by concentrating. But that wasn't the whole story. The brain imaging also showed that when the word task became harder - for instance, syllable-counting rather than identifying the letter's case - the V5 region became less active. People had become more successful at ignoring the starfield.

So what was going on during the harder puzzle? We have a limited capacity for absorbing visual information, says Lavie. "We're not machines. We can't perceive everything." So when a more visually intensive task - such as processing the starfield as well as the word - "loads" the brain's attention, we become increasingly blind to distractions, and our performance on the task will improve: reaction times get faster, and error rates drop. That means that the harder you are forced to concentrate, the less likely you are to be distracted.

The part of the brain in charge of controlling whether we accept or ignore distractions is a region called the parietal cortex. It sits close to the visual cortex, which feeds it information from the eyes for distribution to other parts of the brain. Many studies have shown that the parietal cortex is crucial to concentration. For example, people with lesions in the parietal cortex are known to be less able to concentrate on a task than those with undamaged brains. "Some people equate it to a switchboard," says Lavie. And according to her theory, even when the parietal cortex is healthy, if too many calls come in to it, the switchboard jams and can't accept any new information, however distracting.

Loading the brain to render it blind to distractions is a strategy that has been repeated in various other experiments, and the concept has been widely accepted, says John Duncan, an attention researcher at the University of Cambridge. However, he points out that in the real world the act of focusing our attention is much more complex than demonstrated in Lavie's experiments, which test only visual perception. For example, as you read this article, you might also be trying to screen out the sound of somebody talking nearby, or ignoring "internal" distractions such as stress or hunger, both of which involve different areas of the brain from those in play when we are distracted visually. "There isn't a general ability to keep attention on track," says Duncan.

Nonetheless, Lavie's findings could have practical benefits for anyone who is... well, boring. For example, someone giving a presentation might be able to reduce the impact of distractions elsewhere in the room, not by making their slides clear and easy to read, but by perhaps adding a textured background or moving images.

Lavie and her UCL colleague Sophie Forster are also investigating whether schoolchildren's books and educational materials could be designed to hold attention better. Her theory would suggest that feeding simple tasks to easily distracted kids is the worst thing you can do. "You should think about making educational materials more perceptually engaging. We're trying different colours, patterns and backgrounds," says Lavie. She admits that it's a long shot, and other researchers agree. "Of course if it happened it would be a spectacular result, but I wouldn't invest a large sum in betting on it working," says Duncan.

Back in the lab at UCL, Lavie is scribbling the results of my distractability test on a piece of paper. My score was disappointingly average, but Lavie says it isn't necessarily something I should worry about. Phew. For one minute there, I thought my ability as a writer might suf

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