By Paul Dockree, TCD 

"Not all those who wander are lost" J. R. R. Tolkien, 1958

As the winter evenings grow darker, some of you may have been brave enough to watch the excellent Netflix adaption of Sherley Jackson’s novel, The Haunting of Hill House.  Upon climbing the stairs at bedtime you have my sympathy if disturbing images of the chilling Bent-Neck Lady or the eerie Bowler Hat Man have lingered in your wandering mind long after the lights have gone out, and perhaps even penetrated your dreams. Jackson tells us in the opening paragraph of her novel that "no live organism can continue for long to exist sanely under conditions of absolute reality; even larks and katydids are supposed, by some, to dream." 

Netflix trailer for The Haunting Of Hill House

Recent research in psychology and neuroscience suggests that dreaming shares similar properties with how the mind wanders while awake. In both states, the mental content is often oriented to one’s waking anxieties and preoccupations, both current concerns and imagined future scenarios. It comprises visual imagery, evokes social interactions and draws upon memories grounded in reality, but reconstructs sketchy narratives coloured by fantasy.

Kieran Fox from Stanford University and Kalina Christoff from the University of British Columbia have also demonstrated that dreaming and mind wandering share both similar content and a common neural substrate. Rapid eye movement (REM) sleep - the physiological signature of dreaming - shows overlapping patterns of cortical activity with the brain’s "default mode network". This network becomes active when a person in an MRI scanner is told to "do nothing". This is a considerable challenge for our restless minds, which almost immediately default to spontaneous self-reflective thoughts, future planning and automatic recall of memories. 

We spend a considerable amount of time dreaming and daydreaming. REM sleep persists for approximately two hours per night and the prevalence of mind wandering is estimated to occupy 30 to 50 percent of our waking hours. If dreams are merely epiphenomenal and daydreams are just wasted time, the brain expends a significant amount of metabolic energy generating these spontaneous mental states for reasons that are inexplicable. 

Past thoughts evoked in our dreams and wandering minds are underscored by offline processes in the brain consolidating our recent experiences into long-term memories

One potential function of the emergence of spontaneous, undirected thoughts may, in part, relate to neural processes involved in memory consolidation. Brain areas that subserve the encoding and retrieval of long-term memories – in particular the hippocampal regions – become active during REM sleep and may reflect the reactivation of memory traces for previous behavioural experiences encountered during the day.

Interestingly, there is also evidence to suggest that extensive brain activation of recent memories also occurs during periods of wakefulness after learning, but in the absence of active rehearsal of the learned material. It is conceivable that past impressions and thoughts evoked in our dreams and wandering minds are underscored by offline processes in the brain consolidating our recent experiences into valuable long-term memories. 

Another possible function of these unconstrained states of mind may be to revive and re-appraise past events to throw-up possible future scenarios and new ideas. When the limited bandwidth of goal-directed focus is suspended, there is scope for incubating creative ideas over a broader time window – the content of dreams and mind wanderings typically covers the events of last 48 hours, which contrasts with the sharp focus of events on our daily to-do-list.

The default mode network in the brain which is active when the mind wanders

Setting time aside for mind wandering in a busy schedule can be a constructive process for some. Turn off the phone and, importantly, cast off any guilty feelings that you are wasting time. Negative brooding about uncompleted tasks will inhibit creativity.  A relaxed and calm environment is likely to give rise to more positive and productive mind wandering. Famously, René Descartes claimed that his thoughts were most productive when relaxed and warm while lying in bed. Indeed, his insights into the mathematical unity of nature have been credited to indulging his daydreams.

The vivid fantasy world of Walter Mitty – the quintessential daydreamer -  is a testament to the power of creativity. However, these benefits aside, it is no use being an ineffectual dreamer when there are daily tasks to be done. A challenge for many is taming the wandering mind when focus is required. 

These laboratory experiments are shaping our understanding of the neural processes that guard against an excessively wandering mind

In our work at Trinity College, we have identified the antecedent neural changes that predict unaware lapses of attention when people are struggling to maintain their focus over time. EEG (electroencephalographic) activity reveals fluctuations in the alpha rhythm (8-14Hz), and a slow maladaptive increase in this brain signal predicts an unaware lapse up to 20 seconds before it occurs.  Non-invasive electrical stimulation of the right prefrontal lobe reduces these inattentive lapses, and importantly, can also make people more aware of their mistakes as they occur. 

These laboratory experiments are shaping our understanding of the neural processes that guard against an excessively wandering mind and underlie monitoring of our erroneous behaviours. We are learning that there is a competitive relationship between different brain networks that drive voluntary attention and those that pull towards a default state of mind wandering. How we strike a balance between these online and offline modes of thought is ripe for further investigation. 

Dr Paul Dockree is Associate Professor at the School of Psychology and Institute of Neuroscience at TCDHe was awarded an Irish Research Council Consolidator Laureate Award in 2018.


The views expressed here are those of the author and do not represent or reflect the views of RTÉ