Schools are always being urged to give their pupils a "greener" view of the world. It turns out that there may be benefits to doing this literally, rather than just by promoting environmentalism.
Greener surroundings, with more trees and plants, appear to change pupils' behaviour, making them pay better attention in lessons.
Obviously we might expect better results from students in "leafier" areas for reasons of parental income and class. But one study a decade ago attempted to factor this out. It randomly assigned 169 inner-city girls and boys to 12 architecturally identical high-rise buildings with varying levels of greenery in view.
The researchers found that the greener and more natural a girl's view from home, the better she scored on tests of concentration, impulse inhibition and delayed gratification. They considered this to be because of an improvement in self-discipline - lack of which is "a predictor of delinquency, drug abuse, poor school grades and teenage pregnancy". Self-discipline requires the ability to pay attention, so when your attentional system becomes tired it declines. Greenery is thought to provide "attentional restoration". The boys' results were seen as less conclusive as they spent less time at home and played elsewhere.
A growing number of other researchers now believe that being exposed to greenery has general benefits for children's ability to pay attention. Studies refer to "superior attentional functioning" and say that "the effect of nature on inattention is robust". A study published in the American Journal of Public Health found that exposing children with attention deficit hyperactivity disorder (ADHD) to outdoor greenery was strongly associated with a reduction in their symptoms. And the greener the setting, the greater the reduction.
In a follow-up study, children with ADHD were taken on 20-minute walks in either a city park or one of two, well-kept urban settings. The results were extraordinary: "Effect sizes were substantial and comparable to those reported for recent formulations of methylphenidate (Ritalin)," the researchers said, concluding that "20 minutes in a park setting was sufficient to elevate attention performance relative to the same amount of time in other settings". They also pointed to research conducted among people without ADHD, showing that inattention and impulsivity are reduced after exposure to natural settings.
Similar findings continue to appear a decade later. Academics Andrea Faber Taylor and Frances Kuo examined whether routine play in green spaces could yield ongoing reductions in ADHD symptoms. Their answer, published in 2011, was yes, it seems so: "Children with ADHD who play regularly in green play settings have milder symptoms than children who play in built outdoor and indoor settings."
One of the most influential longitudinal studies, from Cornell University in the US, found that children who experienced the biggest increase in green space near their home after moving improved their cognitive functioning - especially the ability to focus - more than those who moved to areas with fewer natural resources.
Another paper, Can Nature Make Us More Caring? (2009), involved four studies conducted by the University of Rochester in the US examining the effects of exposure to nature on prosocial and other values. Young people "immersed in natural environments" were judged to express greater generosity and concern for others than those immersed in "non-natural environments".
Other research has suggested that plants reduce anxiety and can be responsible for improvements in athletic performance.
Added to this, there is growing evidence that "green exercise" - such as walking or cycling in a natural environment - boosts well-being more than exercise alone. A recent study on this by the School of Biological Sciences at the University of Essex found that "every green environment improved both self-esteem and mood; the presence of water generated greater effects". Most interesting was the finding that "for self-esteem, the greatest change was in the youngest". Small doses of outdoor physical activity for as little as five minutes at a time can significantly improve mental health.
Even in rural areas, a study of 337 school-age children found that the presence of nearby nature - such as indoor plants, natural views or a garden of grass rather than concrete - bolstered a child's resilience to stress and adversity.
To start the love affair between children and nature, many of the researchers above recommend more outdoor playtime, greener playgrounds, more plants in schools, school gardening and school trips to the countryside.
Dr Aric Sigman is a PSHE lecturer.
OUT OF TOUCH
Across the industrialised world, there has been a marked decline in children's contact with nature. A UK study commissioned in 2007 found that, of 1,000 pupils across England, one in five had never visited the countryside and a further 17 per cent had only visited it once or twice.