The Science of Hiking

A journey on foot is an integrative, mind-body activity. As the legs move, the mind wanders. By being forced to focus on realities close at hand, such as negotiating uneven or perilous ground, the brain is freed from having to concern itself with the background worries that otherwise assail it in the course of daily life. As everyday problems fade into irrelevance, the brain enters new territory; attuned to the rhythms of the land underfoot, the mind is free to wander in its own imagined terrains.

For the Romantics, and many other writers and artists since, time spent in nature was for this reason essential to mental wellbeing, and indeed lay at the very heart of the creative process. What the Romantics knew perfectly well, however, has now become a key focus of scientific research. With more than 50% of the world’s population now living in cities, a recent upsurge in interest in the implications of our increasing alienation from the natural world has led to an increased understanding of the importance of time spent in nature in terms of its impact on our psychological wellbeing.

A spate of studies have looked in particular at an apparent link between the rapid and widespread urbanisation that has occurred across the world over the last half-century and a marked rise in instances of mental illness over the same period. The exact cause of this correlation is still unknown, but one theory holds that a decline in the amount of contact we have with the natural world may have something to do with it.

This was the hypothesis of a 2015 study led by Gregory Bratman of Stanford University’s Center for Conservation Biology, who sought to establish what exactly it is that might connect reduced contact with nature to the development of psychological disorders. One explanation, Bratman suggests, could be the impact of nature exposure on ‘rumination’, a maladaptive pattern of self-referential thought focused on negative aspects of the self, known to be a risk factor for depression and other forms of mental illness.

In their study, published in the Proceedings of the National Academy of Sciences last summer, Bratman and his colleagues divided a cohort of 38 city-dwellers into two groups, and asked each group to take a 90-minute walk — one through a grassy area near the Stanford University campus, the other along a busy main road in downtown Palo Alto. Brain scans conducted on those who walked through the natural setting showed reduced neural activity in the specific area of the brain responsible for self-focused behavioural withdrawal associated with the development of mental illness. Those who walked through the urban setting showed no such effects, leading the authors to conclude that even a brief excursion in verdant surroundings substantially decreases obsessive, negative thoughts.

Bratman’s study follows in a tradition of scholarship rooted in a school of thought known as Attention Restoration Theory (ART). Pioneered in the 1980s by Rachel and Stephen Kaplan in their book The Experience of Nature: A Psychological Perspective, ART suggests that exposure to nature has specific effects on our executive attentional system, which can become worn down due to the demands made of it by urban life.

Permanent background noise, compulsive and increasingly compulsory engagement with technology, the demands of multi-tasking and the necessity of constantly having to respond to sudden, disruptive stimuli place a severe strain on our cognitive functions. By contrast, natural environments, according to Attention Restoration Theory, are rich in characteristics necessary for the brain to replenish itself.

This hypothesis has been found to hold true in a slew of studies since the 1980s. A well-known experiment by Terry Hartig and colleagues, for example, comparing the attentional capacity of wilderness vacationers, urban vacationers and non-vacationers before and after their respective holidays, found that the wilderness group showed significant improvements in attentional capacity, measured through proof-reading tests. In another study, Hartig et al. divided a cohort of participants into three groups, all of which completed attention-depleting tasks and then spent 40 minutes walking in a natural setting, walking in an urban setting, or listening to music and reading magazines. Again, participants in the nature walk group significantly outperformed the others at the proof-reading task, affirming a substantial recovery in directed attention.

Similar studies have found that interactions with nature lead to improved performance on Attention Network Tasks and backwards digit span tests used to assess working memory, the cognitive system responsible for temporary storage and manipulation of information. Even looking at images of nature has been shown to have such effects. This kind of ‘passive’ interaction with nature, as opposed to more active engagement in the form of hiking, was the subject of an oft-cited piece of research by Carolyn Tennessen and Bernadine Cimprich, which found that college students whose dormitories looked out onto more pastoral vistas scored better on a range of attentional measures than those with views of less bucolic landscapes.

Exposure to nature thus seems to be effective in replenishing lower-level modules of the executive attentional system. But there is a growing body of evidence to suggest that it may also have an impact on higher-level tasks, such as creative problem solving.

In a 2012 study, psychologists David L. Strayer and Ruth and Paul Atchley sent a group of participants on a four-day wilderness hike, completely cut off from technology, and subsequently asked them to carry out tasks requiring creative thinking and complex problem solving. The study found that participants’ performance on these tasks improved by 50%, leading the authors to conclude that “[t]here is a real, measurable cognitive advantage to be realized if we spend time truly immersed in a natural setting”.

This improvement of higher-order cognitive skills derives, the authors of the latter study argue, from “an increase in exposure to natural stimuli that are both emotionally positive and low-arousing and a corresponding decrease in exposure to attention demanding technology, which regularly requires that we attend to sudden events, switch amongst tasks, maintain task goals, and inhibit irrelevant actions or cognitions.”

Whereas the stimuli we encounter in nature, as University of Michigan professor Marc Berman explains, “modestly grab attention in a bottom-up fashion, allowing top-down directed-attention abilities a chance to replenish”, urban environments are “filled with stimulation that captures attention dramatically and additionally requires directed attention (e.g., to avoid being hit by a car), making them less restorative.”

The efficacy of exercise per se on cognitive function and emotional wellbeing is fairly well-established, but the full extent of the role of nature exposure in particular, and the mechanisms by which it affects us, is only now beginning to be understood in all its complexity. A hike in the countryside is rich in unique characteristics that will do more for the human brain than any amount of time on a treadmill ever can – that much is clear – and in a rapidly urbanising world, the findings of ongoing research in this field will almost inevitably have ever more profound and far-reaching implications.


Foot People

In the 1993 republication of The Death and Life of Great American Cities, the world’s most famous urban planner, Jane Jacobs, argues that there are two kinds of people in the world: “foot people” and “car people”. The former are those who tend to organise their lives around pedestrian travel, who “prefer doing their workaday errands on foot, or feel they would like to if they lived in a place where they could”, the latter those who prefer “hopping into the car to do errands, or would like to if they had a car.”

I’ve always been a ‘foot person’. Partly this is because I’ve always been a countryside person. I grew up in a small rural community in the north of England. The nearest shop was a mile’s walk away, which in the Yorkshire winters was no easy undertaking, but for me it was the norm – and as a devoted nicotine enthusiast, it was a walk that I would be compelled to make, regardless of the weather. It was what I grew up with. As a teenager I held down several jobs in various local pubs, and would walk a couple of miles to work every day, and back each night. The nearest bus-stop was a mile’s walk from my home; if I wanted to travel further afield, that was a mile I would have to walk.

Having walked everywhere during one’s formative years engenders a frame of reference when it comes to space and distance unlike that of someone accustomed to driving everywhere, or having everything right there on their doorstep – just as an American’s conception of what constitutes a ‘long’ car journey inevitably differs from that of a Brit, raised on a tiny island where a three-hour trip up the M6 is an event.

Since the city became an inevitability, perhaps unsurprisingly I’ve always found that small ones suited me best. Partly out of necessity and partly out of choice I’ve always chosen where I live based on the potential for getting where I need to be, day to day, without having to own a car. Unlike many neighbourhoods in, say, the United States, built specifically for cars and thus with little connectivity, the older urban areas in England were designed and built before the mass production of the motor-car and are thus generally very walkable, and there is no excuse not to use that feature to its full advantage.

There is a psychological, emotional and creative aspect to walking in the hills, however, which can’t be approximated by urban wanderings. Harvard physician Paul Dudley White, known to history as the ‘father of American cardiology’, believed that a brisk, five mile walk every day is as good a remedy for a restless mind as anything the worlds of medicine and psychology have to offer. Dr. White well understood the physiological benefits of walking, but like many others before and since he was also a firm believer in the positive effects of the outdoors on our intellectual, creative and emotional faculties.

For the English Romantics, through whose influence wandering the countryside à pied became a popular leisure pursuit in England in the late 1700s, time spent in nature was not only a source of literary inspiration (in + spirare – ‘to breathe in’), but fundamental to the creative process. William Godwin “made whole books” as he walked. Across the Channel, Jean-Jacques Rousseau, who spent much of his youth wandering the hills of Central Europe, found in the natural world a clarity of thought that eluded him amid the bustle of urban life. “Cities”, Rousseau concluded, were “the abyss of the human species”.

Not all have shared Rousseau’s distaste for the metropolis of course – many literary notables, from Charles Dickens to Will Self, have remarked on the restorative effects of peregrinations through the urban jungle – but it’s in rural environs that most who have written on the subject claim to have reaped the medicinal rewards of a good walk. George Orwell, Thomas De Quincey, Friedrich Nietzsche, Ralph Waldo Emerson, Søren Kierkegaard, Thomas Mann, Vladimir Nabokov, and of course Henry David Thoreau all extolled the virtues of getting out into the natural world. The physicist Werner Heisenberg was a keen hiker, as were Paul Dirac, Otto Frisch and Lise Meitner, all of whom reported having come to key scientific discoveries while walking in the countryside.

* * *

This was intended to be a post saying a few words by way of introducing this blog and explaining something of what it’s likely to be about, but on reflection there are actually a number of distinct aspects to what I want to do with this site, each of which, if only in the interests of keeping these posts to a manageable length, should perhaps have its own prefatory remarks. So, to be continued….


“As a single footstep will not make a path on the earth, so a single thought will not make a pathway in the mind. To make a deep physical path, we walk again and again. To make a deep mental path, we must think over and over the kind of thoughts we wish to dominate our lives.”

– Henry David Thoreau

“The dull man goes straight forward; he has so many furlongs to traverse. He observes if he meets any of his acquaintance; he enquires respecting their health and their family. He glances perhaps the shops as he passes; he admires the fashion of a buckle, and the metal of a tea-urn. If he experience any flights of fancy, they are of a short extent….

On the other hand the man of talent gives full scope to his imagination…. His whole soul is employed. He enters into nice calculations; he digests sagacious reasonings. In imagination he declaims or describes, impressed with the deepest sympathy, or elevated to the loftiest rapture…. He passes through a thousand imaginary scenes, tries his courage, tasks his ingenuity, and thus becomes gradually prepared to meet almost any of the many-coloured events of human life. ….

If he observe the passengers, he reads their countenances, conjectures their past history, and forms a superficial notion of their wisdom or folly, their virtue or vice, their satisfaction or misery. If he observe the scenes that occur, it is with the eye of a connoisseur or an artist. Every object is capable of suggesting to him a volume of reflections.”

– William Godwin

“When I stay in one place I can hardly think at all; my body has to be on the move to set my mind going.”

– Jean-Jacques Rousseau