Daydreaming is the result of the brain reverting to its normal state in the absence of engaging problems, rather than a pointless distraction, according to U.S. researchers

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ADELAIDE: Our minds may wander during boring tasks because daydreaming is actually the brain's normal state, rather than a pointless distraction, according to a new U.S. study.

The researchers, reporting their findings today in the U.S. journal, Science, found that daydreaming could be the result of the brain mulling over important - but not immediately relevant - issues when the external environment ceases to pose interesting and engaging problems.

"For the most part psychologists have sort of assumed that we spend most of our time engaged in goal-directed thought and that, every so often, we have blips of irrelevant thoughts that pop up on the radar," said lead author Malia Mason of Harvard University in Cambridge, Massachusetts.

"It could very well be the case, however, that most of the time we are engaged in less directed, unintended thought and that this state is routinely interrupted by periods of goal-directed thought."

Daydreaming or mind-wandering - familiar to one and all - is more precisely defined as a state of mind where thoughts that are experienced by an individual are unrelated to what is going on in the environment around them, according to Mason. When wandering, the brain flits from one thought to the next, generating images, voices, thoughts and feelings.

"This type of [wandering] thought can be fanciful and it can be problematic and distracting, but usually it's quite practical, for example, most people spend the time thinking about what they need to do in the impending future," said Mason.

When deciding how best to encourage daydreaming in order to study it, the researchers recognised that our minds often wander while we are engaged in familiar tasks, such as making a tuna fish sandwich, because we don't need to concentrate on it. They trained study subjects to become proficient on certain tasks so that their minds would be able to wander when they performed them, but would have to concentrate when given something new.

The team used functional magnetic resonance imaging (fMRI) to learn what parts of their brains were active during both goal-oriented thought and daydreaming. In the fMRI images, the seat of daydreams appeared to be the 'default network' a region of the brain that remains active when we rest or are not engaged in a focussed task, but switches off when we need to concentrate.

The default network is a collection of regions from the medial frontal and medial parietal regions of the brain. The frontal lobes are involved in functions including impulse control, judgment, language, memory, motor function, problem solving, sexual behavior, socialisation and spontaneity. The parietal lobe plays an important part in processing sensory information.

Previous studies have shown that brain damage to parts the default network is associated with a "mental emptiness" and an absence of spontaneous speech and thought.

According to Mason, the most important question is why our brains evolved to wander at all. His team suggests that perhaps it keeps our brains aroused during mundane tasks, or simply that our brains may wander because they can.

"In a sense these thoughts reflect an amazing capacity on our part to multi-task," said Mason. "It is as if we have a sense of how much [attention] we have 'left over' and allocate these resources to working out some problem or anticipating what we have to do in the near future."