Some people can concentrate for long periods of time, while others are easily distracted, and this, according to new research, may be because we all lie somewhere on an attention-distractibility spectrum, with people who suffer from Attention-Deficit Hyperactivity Disorder (ADHD) being at one extreme of it.
Sophie Forster of the University of Sussex and Nilli Lavie of University College London recruited 100 healthy undergraduate volunteers, and asked them to perform a computerized visual search test in which they had to find a 'target' letter within a circle of others.
The test varied in difficulty, with some of the targets being placed within a circle of other similar letters, making them harder to find. In some of the trials, the letters where shown with an irrelevant and distracting cartoon image beside them.
The researchers found that their participants' performance varied widely. Some were far more easily distracted by the cartoons than others, as determined by the time it took them to correctly identify the target letter. The more difficult version of the test eliminated this distraction.
Afterwards, all the participants filled out a self-report form designed to measure the extent to which they experienced ADHD-like symptoms in their childhood. This revealed a close link between childhood symptoms and distractibility during the lab test, with those reporting more symptoms being the most easily distracted.
In a second experiment, 101 other volunteers were asked to perform a similar test, this time involving the names of superheroes and other fictional characters, and without a more difficult version. Confirming the results of the first experiment, Forster and Lavie found large individual differences in performance, which again were closely correlated with the participants' self-reports of ADHD-like symptoms in childhood.
"We find that peoples' self-reports of their ADHD-like symptoms in childhood predict the level of distraction they experience in adulthood," says Lavie. "That's why we think attention-distractibility is a long-lasting trait. Otherwise, how would childhood symptoms predict their performance?"
Lavie adds that attention-distractibility may be a 'core' personality trait that persists through life, and this could explain the observed individual differences in the extent to which healthy people can focus their attention.
Attention acts as a 'gateway' to information processing in the brain, because stimuli that aren't attended to do not enter into conscious awareness. People diagnosed with ADHD typically underachieve at school, and are more prone to accidents in daily life. Similarly, distractibility scores predict the likelihood of work and car accidents in healthy people. The observation that the more difficult version of the tests eliminated distraction in all participants, regardless of the extent of their self-reported childhood ADHD-like symptoms, suggests that cognitive training could help people to focus their attention more.
"We are now working on establishing the distraction test as a commercial product," says Lavie. "We are looking to help people with non-clinical ADHD symptoms to learn more about themselves."