Watching the mind travel: Understanding internal distraction from our own involuntary thoughts

At any given moment, our brains are making choices about what to focus on - a process called selective attention. These choices are necessary because we are constantly exposed to an enormous amount of information, which vastly exceeds our brain's processing capacity. However, sometimes our brains appear to make the wrong choices.

For example, while trying complete an urgent work task, we may find our attention has switched, against our will, to thinking about our lunch plans. A driver may be distracted by a passer-by and miss a red traffic light. A school child may be distracted by thoughts about an argument with a friend and miss a key part of their lesson.

Regardless of the source of distraction, the consequences for task performance are the same: When we are distracted our ability to learn, work, drive or do any other task is seriously compromised.

Industries are built around attempts to minimize distraction, typically targeting the environment (e.g. noise-cancelling headphones). However, this will not work when the distraction comes from our own thoughts, as is the case much of the time. Beyond their disruptive impact on tasks, involuntary thoughts cause further harm through their capacity to expose us to information we would prefer to avoid: A person trying to sleep may find their thoughts returning, against their will, to a work-related situation.

A recovering alcoholic might stay away from bars but be unable to escape thoughts about drinking. A person may be intensely distressed by unwanted thoughts or imagery relating to a past trauma. From the disruptive distracting thoughts experienced in daily life, the disturbing intrusive thoughts associated with anxiety disorders, to the tempting thoughts associated with addiction, all these experiences have in common the underlying phenomenon of an involuntary thought.

We lack a fundamental understanding of what causes involuntary thoughts to happen. In other words, how does a particular piece of information from our minds suddenly hijack our consciousness?

Decades of research into selective attention have given us a rich insight into the causes of distraction by external information (e.g., sights, sounds). Surprisingly, this field has almost entirely neglected the topic of distraction by our own involuntary thoughts - limiting the ability of selective attention models to explain real world distraction.

This omission is likely due to methodological barriers - the uncontrollable, unpredictable and subjective nature of involuntary thoughts means they cannot easily be studied using traditional approaches. However, advances in neuroimaging techniques open up the exciting opportunity to fill this gap in the literature and build a comprehensive understanding of the causes of distraction from all sources.

The proposed research will use a novel neuroimaging approach, combined with behavioural experiments, to develop and test a new model of internal distraction by involuntary thoughts. The neuroimaging approach involves planting a specific thought in people's minds, before they perform an unrelated task: Pilot data show that specific involuntary thoughts can be tracked through their unique neural signature.

By studying the communication between these 'marker' thoughts and other brain regions, we can identify the networks involved in involuntary thoughts. Behavioural experiments will test which types of thought are most distracting, and how these vary from person to person. Using this approach, we will test whether what we know about how the brain selects sensory information - and we know a lot - might apply to predict how our minds choose our thoughts.

Understanding how our brains cause involuntary thoughts is a fundamental stepping stone that in the longer term can help us to explain - and ultimately predict, control or prevent - their negative, sometimes disastrous, consequences for education, productivity, health and safety, and mental health.