A photograph of a forest may be enough to alter activity in parts of the brain involved in emotional distress.
That was the finding of a study by Italian researchers investigating something most people recognise instinctively: the sense that being around nature can change how we feel. Their experiment suggests that the effect may involve more than personal preference or the pleasure of a good view.
Published in Frontiers in Psychology, the study examined the brain activity of 53 young adults before and after they viewed a series of photographs. Half saw natural settings, the other half urban environments. Those shown green spaces subsequently reported more positive emotions and a greater sense of vitality. Their EEG recordings also revealed a change in the way two areas of the brain associated with emotional processing and stress were communicating.
The experiment was deliberately simple. Twenty images were shown for 12 seconds each. Participants were free to look at them as they wished, then underwent a second five-minute resting EEG and completed questionnaires about their mood.
The group exposed to nature reported feeling more positive and more “full of energy and alive”. More unusually, researchers detected reduced connectivity between the left insula and the left subgenual anterior cingulate cortex, two regions implicated in how we process emotion and respond to stress.
The finding adds to a body of research that has been building for several decades around the restorative effects of natural environments.
In 1984, American environmental psychologist Roger Ulrich published a study that became a landmark in the field. Looking through hospital records, he compared patients recovering from gallbladder surgery whose rooms overlooked trees with those whose windows faced a brick wall. The patients with the natural view had shorter postoperative stays, received fewer negative comments in nurses’ notes and required fewer strong painkillers.
The study was small, involving 46 patients, but it raised a question that has since become considerably more sophisticated: does the environment simply affect our mood, or can it influence the biological processes that sit behind it?
In 2015, researchers at Stanford University studied people who walked for 90 minutes either through a natural landscape or beside a busy road. Those who took the nature walk reported less rumination, the repetitive dwelling on negative thoughts, and showed reduced activity in the subgenual prefrontal cortex, an area associated with that pattern of thinking.
The Italian EEG study approaches the subject from another direction. Rather than asking only which parts of the brain are more or less active, it looks at the connections between them.
The insula plays a role in interpreting signals from the body and identifying emotionally significant information. The subgenual anterior cingulate cortex is involved in emotional regulation and the body’s responses to stressful events. The researchers note that unusually increased connectivity between the two has previously been associated with negative emotional responses following stress. After participants looked at the nature photographs, connectivity between these regions decreased.
Why should looking at greenery make any difference at all?
Two established theories have shaped much of the research in this area. Stress Reduction Theory proposes that natural environments prompt automatic physiological responses that help moderate stress. Attention Restoration Theory suggests something different: nature gives the brain relief from the sustained, deliberate attention required by everyday life.
The distinction is useful. A crowded street requires us to monitor traffic, signs, people and noise. Much of our working day demands the same selective attention, whether we are reading, driving, answering messages or moving between screens. Natural settings can hold the attention without requiring the same effort. Psychologists have been studying that contrast since the late 20th century.
The new findings do not prove that looking at trees will treat stress, anxiety or depression. Nor do they establish that a picture of a landscape produces the same response as actually being outdoors.
The study population was young and relatively small, with an average age of just over 21, and 42 of the 53 participants were women. The researchers also recorded what happened immediately after the photographs were viewed, so the experiment tells us nothing about how long the neurological effects might last. They acknowledge that larger studies and more sophisticated brain imaging will be needed to understand the finding properly.
There is another detail worth noting. The participants rated the nature images as more pleasant, brighter, more familiar and higher in quality than the urban photographs. Beauty, familiarity and nature are not easily disentangled in an experiment of this kind.
But that difficulty is also pushing the research in more interesting directions. The authors suggest future studies comparing different kinds of landscapes, from forests and parks to seas, lakes, mountains and deserts. They also point to hiking, gardening and swimming as possible areas of investigation, as well as virtual and multisensory versions of nature incorporating sound and scent.
The question is increasingly relevant to the way we design cities, workplaces, hospitals and homes. Nature has often been treated as an aesthetic addition to the built environment. Research such as this suggests that the distinction between what looks good and what makes us feel better may be less straightforward than it seems.
A window onto trees, a walk through a park or even an image of a landscape cannot be reduced to a prescription. But the biological response to nature is becoming harder to regard as incidental.
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