Those who are easily distracted from the task in hand may have "too much brain".
So says Ryota Kanai and his colleagues at University College London, who found larger than average volumes of grey matter in certain brain regions in those whose attention is readily diverted.
To investigate distractibility, the team compared the brains of easy and difficult-to-distract individuals.
They assessed each person's distractibility by quizzing them about how often they fail to notice road signs, or go into a supermarket and become sidetracked to the point that they forget what they came in to buy. The most distractible individuals received the highest score.
The team then imaged the volunteers' brains using a structural MRI scanner. The most obvious difference between those who had the highest questionnaire scores – the most easily distracted – and those with low scores was the volume of grey matter in a region of the brain known as the left superior parietal lobe (SPL). Specifically, the easily distracted tended to have more grey matter here.