Andrade (2010) studied attention and memory. When a task is boring, people start to daydream, and daydreaming takes attention away from the task. Andrade asked whether doodling helps people to concentrate on a dull task or distracts them.
Forty adults listened to a dull mock telephone message about a party and wrote down the names of the people who were coming. Half of them also shaded in shapes on a sheet of paper while they listened. Afterwards everyone had a surprise memory test on the names and on the places mentioned.
The doodlers remembered more. Doodling seems to help concentration, perhaps because it reduces daydreaming without using much of the mind's capacity.