Until recent times, attention has always been quite a mysterious faculty. We’ve never doubted attention mattered, but it’s only in the past few years that we’ve appreciated how absolutely central it is for all aspects of cognition, from perception to memory. The rise in our awareness of its importance has come in the wake of, and in parallel with, our understanding of working memory, for the two work hand-in-hand.
In December 2008, I reported on an intriguing study (go down to "Previous study")that demonstrated the value of a walk in the fresh air for a weary brain. The study involved two experiments in which researchers found memory performance and attention spans improved by 20% after people spent an hour interacting with nature. There are two important aspects to this finding: the first is that this effect was achieved by walking in the botanical gardens, but not by walking along main streets; the second — far less predictable, and far more astonishing — was that this benefit was also achieved by looking at photos of nature (versus looking at photos of urban settings).
Now, most of us can appreciate that a walk in a natural setting will clear a foggy brain, and that this is better than walking busy streets — even if we have no clear understanding of why that should be. But the idea that the same benefit can accrue merely from sitting in a room and looking at pictures of natural settings seems bizarre. Why on earth should that help?
Well, there’s a theory. Attention, as we all know, even if we haven’t articulated it, has two components (three if you count general arousal). These two components, or aspects, of attention are involuntary or captured attention, and voluntary or directed attention. The first of these is exemplified by the situation when you hear a loud noise, or someone claps you on the shoulder. These are events that grab your attention. The second is the sort you have control over, the attention you focus on your environment, your work, your book. This is the type of attention we need, and find so much more elusive as we get older.
Directed attention has two components to it: the direct control you exert, and the inhibition you apply to distracting events, to block them out. As I’ve said on a number of occasions, it is this ability to block out distraction that is particularly affected by age, and is now thought to be one of the major reasons for age-related cognitive impairment.
Now, this study managed to isolate the particular aspects of attention that benefited from interacting with nature. The participants were tested on three aspects: alerting, orienting, and executive control. Alerting is about being sensitive to incoming stimuli, and was tested by comparing performance on trials in which the participant was warned by a cue that a trial was about to begin, and trials where no warning was given. Alerting, then, is related to arousal — it’s general, not specifically helpful about directing your attention.
Orienting, on the other hand, is selective. To test this, some trials were initiated by a spatial cue directing the participant’s attention to the part of the screen in which the stimulus (an arrow indicating direction) would appear.
Executive control also has something to do with directed attention, but it is about resolving conflict between stimuli. It was tested through trials in which three arrows were displayed, sometimes all pointing in the same direction, other times having the distracter arrows pointing in the opposite direction to the target arrow. So this measures how well you can ignore distraction.
So this is where the findings get particularly interesting: it seems that looking at pictures of nature benefited executive control, but not alerting or orienting.
Why? Well, attention restoration theory posits that a natural environment gives your attentional abilities a chance to rest and restore themselves, because there are few elements that capture your attention and few requirements for directed attention. This is more obvious when you are actually present in these environments; it’s obvious that on a busy city street there will be far more things demanding your attention.
The fact that the same effect is evident even when you’re looking at pictures echoes, perhaps, recent findings that the same parts of the brain are activated when we’re reading about something or watching it or doing it ourselves. It’s another reminder that we live in our brains, not the world. (It does conjure up another intriguing notion: does the extent to which pictures are effective correlate with how imaginative the person is?)
It’s worth noting that mood also improved when the study participants walked in the park rather than along the streets, but this didn’t appear to be a factor in their improved cognitive performance; however, the degree to which they felt mentally refreshed did correlate with their performance. Confirming these results, mood wasn’t affected by viewing pictures of nature, but participants did report that such pictures were significantly more refreshing and enjoyable.
Now, I’ve just reported on a new study that seems to me to bear on this issue. The study compared brain activity when participants looked at images of the beach and the motorway. The researchers chose these contrasting images because they are associated with very similar sounds (the roar of waves is acoustically very similar to the roar of traffic), while varying markedly in the feelings evoked. The beach scenes evoke a feeling of tranquility; the motorway scenes do not.
I should note that the purpose of the researchers was to look at how a feeling (a sense of tranquility) could be evoked by visual and auditory features of the environment. They do not refer to the earlier work that I have been discussing, and the connection I am making between the two is entirely my own speculation.
But it seems to me that the findings of this study do provide some confirmation for the findings of the earlier study, and furthermore suggest that such natural scenes, whether because of the tranquility they evoke or their relatively low attention-demanding nature or some other reason, may improve attention by increasing synchronization between relevant brain regions.
I’d like to see these studies extended to older adults (both of them were small, and both involved young adults), and also to personality variables (do some individuals benefit more from such a strategy than others? Does reflect particular personality attributes?). I note that another study found reduced connectivity in the default mode network in older adults. The default mode network may be thought of as where your mind goes when it’s not thinking of anything in particular; the medial prefrontal cortex is part of the default mode network, and this is one of the reasons it was a focus of the most recent study.
In other words, perhaps natural scenes refresh the brain by activating the default mode network, in a particularly effective way, allowing your brain to subsequently return to action (“task-positive network”) with renewed vigor (i.e. nicely synchronized brainwaves).
Interestingly, another study has found a genetic component to default-mode connectivity (aberrant DMN connectivity is implicated in a number of disorders). It would be nice to see some research into the effect of natural scenes on attention in people who vary in this attribute.
Meditation is of course another restorative strategy, and I’d also like to see a head-to-head comparison of these two strategies. But in any case, bottom-line, these results do suggest an easy way of restoring fading attention, and because of the specific aspect of attention that is being helped, it suggests that the strategy may be of particular benefit to older adults. I would be interested to hear from any older adults who try it out.
[Note that part of this article first appeared in the December 2008 newsletter]