Evidence

There is a large and growing body of good quality research evidence that nature has a positive effect on us. Here are ten key pieces of work.

Citation

Ulrich RS ‘Biophilia, Biophobia, and Natural Landscapes’ 73-137p in Biophilia Hypothesis ed Kellert SR and Wilson EO 1993 Island Press Washington

Trees help us relax

People can cope with a stressful thinking task better if they have spent time walking in an natural environment compared to walking in an urban environment or to sitting at home reading a magazine.

A variety of studies (recording verbal responses and physiological measures such as EEG, heart rate, skin conductance) confirm that people recover from a stressful event more quickly if they experience a natural setting compared to an urban environment. Key features that can help a positive setting include a grassy park like landscape and a prominent water feature. Recovery is also quite fast: only 4 to 6 minutes of exposure to natural versus urban settings significantly restores relaxation levels as measured physiologically.

Having the opportunity to view natural scenes (as opposed to other images) for brief periods significantly lowered stress levels in patients in a pre-operation room. Similar results work for patients in the dentist chair if they can look at a natural scene during treatment.

 

Greening neighbourhood areas cuts crime

Frances Kuo and Bill Sullivan at the ACES Human-Environment Research Laboratory in Chicago studied how people’s behaviour was affected by the amount of greenery outside their home. Their results are very positive. They went to a newly built and notoriously tough housing complex of 28 identical 16 storey high rise buildings on a three mile corridor, the biggest in the world at the time. Residents had been randomly assigned to apartments by the Chicago city authorities Some had trees and other vegetation near their block, some did not. The researchers trained local residents to interview other residents who matched them in ethnic origin and gender.

The results of the research indicated distinct differences between those people who lived with nearby trees and those who had a barren landscape. People with trees knew and socialised more with neighbours, had a stronger sense of community, and felt safer than the residents who lived in a treeless outdoor environment.

Further research delved deeper. Kuo and Sullivan observed that children and adults gathered more in the places with trees than in the barren areas.

Violence was also less frequent when people were living near trees. Of 150 residents interviewed 14% living in the barren blocks threatened or used a knife or gun with their children (sic!); only 3% did so from the tree’d areas.

The explanations are obvious: people who had trees around them were more likely to feel stressed and tense. This meant in turn that they were more able to feel safe with neighbours and more willing to not only talk to but help others.

Residents were shown computer adapted images of their neighbourhood and asked to rate how they felt about them. The green areas got the thumbs up; people said they would feel safer. The police had predicted that trees would increase people’s fear (potentially a place for muggers to hide?) but the residents disagreed. The researchers say, ‘Overwhelmingly, people living in housing developments want trees yet thousands look over concrete.’

The effect of designing green nature into our cities and towns is not just about making the place look pretty.  A green city not only improves community spirit and reduces crime but it saves money in policing and social work. City hall understood this. As a result of the research programme Chicago city government invested $10 million in planting 20,000 trees.

Another study by Kuo and Sullivan found that children played outdoors twice as much if trees were present, engaged in more creative play, and mixed with adults more.

Citation

The Power of Trees

http://lhhl.illinois.edu/media/thepoweroftrees.htm

www.herl.uiuc.edu

 

Citation

1. Kaplan R Kaplan, S. (1989). The experience of nature: A psychological perspective. Cambridge University Press.. Kaplan S. The restorative benefits of nature: Toward an integrative framework. Journal of Environmental Psychology 1995, 15, pp169-182

2. Hartig T, Mang M and Evans GW (1991). Restorative effects of natural environment experience. Environment and Behaviour, 23, 3-26.

3. ‘Tracking restoration in natural and urban field settings’ Terry Hartig, Gary W. Evans, Larry D. Jamner, Deborah S. Davis, Tommy Garling. Journal of Environmental Psychology 23 (2003) 109–123

4. Cimprich, B. (1993). Development of an intervention to restore attention in persons with cancer. Cancer Nursing, 16(2), 83-92

 Nature Immunises Against Stress

Spending long periods of time on a focused activity, such as working on a computer, where we have to focus and filter out irrelevant information is not good for us. It can cause stress, anxiety, irritability with others and an inability to concentrate. Spending time in nature, even for short periods, can aid mental recovery and improve one’s ability to concentrate.

1. Attention Restoration Theory ART

Attention is when we focus on one thing and screen out other inputs to our mind. Attention increases our perception, thinking, and memory. We can do this voluntarily.  For example, when we actively pay attention to something such as a task on a computer by filtering out background noises etc.

Over a period of time if we have to deal with complex thinking, anxieties or worries, interpersonal demands, noise or pain we can become fatigued and show signs of stress, tiredness, irritability, impulsiveness, and lack of concentration.

The Kaplans  describe four forms of involuntary attention which restore a persons ability to deal with voluntary attention and overcome fatigue.

Being Away – when we give ourselves a break from overused brain activities.

Fascination – an effortless involuntary attention to things.

Extent – sufficient interest to attract attention without boredom.

Compatability – means the activity fits in with a person’s inclinations and purpose in preventing mental effort.

The natural environment allows for all four circumstances to occur and the Kaplans research (over decades) supports the notion that time in nature restores a persons mental energy.

Three studies are referred to here which support the ART notion.

2. Attention, recovery and nature

Young people were given the task of proof reading, something that requires sustained attention. They were then put in one of three environments for 40 mins, after which their attention skills were measured again. The three environments were a natural environment, an urban environment and passive relaxation (sitting in a room listening to music and reading magazines). Those people who spent time in a natural environment scored highest on the subsequent proof reading test.

3. Attention and stress recovery in nature

112 randomly assigned young people were compared on: their ability to pay attention to a task; their emotional state; and their physiological stress indicators (i.e. blood pressure). They were placed in three different environments, either indoors, outdoors in an urban setting, or outdoors in nature. The results demonstrate the positive effect of nature in restoring a healthy physical and psychological state:

A room with a view of trees was better than a viewless room.

A walk in a nature reserve was better than an urban walk.

Attention improved on the nature walk and declined in the urban. And the effect persisted after the walks had ended.

Positive feelings and reduced anger occurred after the nature walk and increased in the urban.

4. Cancer recovery and nature

Breast cancer can be stressful and drain a woman’s ability to focus and concentrate. Cimprich studied a randomised group of 32 women who were recovering from breast cancer. There was a control group and an intervention group. The latter agreed to 20-30 mins, three times a week, of nature based activities. The typical activities were walking or sitting in a park, bird watching or tending flowers and plants. Her results show a consistently greater improvement in attention in the intervention group, presumably because they became less stressed.

Kids prefer the wild to gardens

When children play in wild nature by going for hikes or playing in the woods this has more positive long term effects on them than picking flowers, planting seeds or trees.

Children now spend less time outdoors than in previous times. Time outdoors dropped from 86 to 42 minutes a day between the 1980s and 2000. Outside play today is more likely to be organised and managed by adults. The suggestion is that our children should be more ‘free range’ and allowed to explore in a free unstructured way our local streets, fields and gardens. It would enhance children’s social relationships, confidence in risk taking and exploration, as well as connections to nature; the research evidence shows that time in nature enhances these benefits.

The evidence also points to childhood experiences in nature continuing in to adulthood and to a more positive desire to protect the natural world.

Citation

Pretty J, Angus C, Bain M, Barton J, Gladwell V, Hine R, Pilgrim S, Sandercock S and Sellens M. 2009. Nature, Childhood, Health and Life Pathways. Interdisciplinary Centre for Environment and Society Occasional Paper 2009-02. University of Essex, UK.

Citation

1. Takano T, Nakamura K, Watanabe M. Urban residential environments and senio citizens’longevity in megacity areas. The importance of walkable green spaces. Journal of Epidemiological Community Health 2003; 56: 913-918.

2. de Vries S, Verheij RA, Groenewegen PP, Spreeuwenberg P. Natural environments -healthy environments? An exploratory analysis of the relationship between green space and health. Environment and Planning 2003; 35: 1717-1731.

3. Mooney, P. and Nicell, P.L. (1992) “The importance of exterior environment for Alzheimer’s residents: Effective care and risk management”,Health Care Management Forum, vol: 5, (2), pp. 23-29.

Spend time in nature and people live longer and memory lasts

1. Japan

Japanese researchers studied the relationship between access to greenspace and mortality in Tokyo. They looked at a large sample of more than 3,000 people of 70 and over. They controlled for sex, age, civil status, district and other parameters. Over five years they recorded everyone who died in the cohort and found a direct relationship between having walkable access to green space near to where a person lived and living longer.

2. Netherlands

Another study in the Netherlands (sample 17,000) showed that people who lived with in easy reach of green space enjoyed better health particularly among the elderly, housewives and lower socioeconomic groups.

3. USA

Researchers looked at five long term care homes for patients experiencing Alzheimers, three homes didn’t have a gardens, the other two had gardens. Because of the progressive deterioration of cognitive facilities aggressive assaults are increasingly more frequent with patients with Alzheimers. This was the case at the homes without gardens. Those with gardens stayed the same or showed a slight decrease in aggressive assaults. “In the garden institutions, the rate of violent incidents declined by 19% between 1989 and 1990 while the total rate of incidents fell by 3.5% over the same period. In the non-garden institutions, the rate of violent incidents increased by 681% and the total rate of incidents increased by 319%”.

Look at plants and relax

Two Japanese researchers looked at the effects on the brain of a person looking at plants. They found that the experiences had a positive measurable effect. In one study the researchers had people look at two types of potted plants: Pelargonium and Begonia, either in flower or not, and lastly looking at a human made cylinder similar to the pots. The people had their brain’s alpha rhythms measured as indicators of a wakeful relaxed state. The results showed that the most relaxed alert state was with the flowering plants, followed by the non-flowering plants and finally the cylindrical pots. In the second study they took people outdoors and had them look at either a hedge, a concrete fence of about the same dimensions, or a mixed view part hedge part concrete fence. The researchers measured their EEG (electro-encephalogram) and the results indicated that the green hedge induced the most relaxed states, whereas the concrete fence had a stressful influence.

Citation

Nakamura, R. and E. Fujii (1990). Studies of the characteristics of the electroencephalogram when observing potted plants: Pelargonium hortorum“Sprinter Red” and Begonia evansiana. Technical Bulletin of the Faculty of Horticulture of Chiba University, 43: 177-183. (In Japanese with English summary)

Nakamura, R. and E. Fujii (1992). A comparative study of the characteristics of the electroencephalogram when observing a hedge and a concrete block fence. Journal of the Japanese Institute of Landscape Architects, 55: 139-144. (In Japanese with English summary.)

Love of nature is in our DNA

Feeling relaxed and more positive while walking in the countryside or along a beach is hard wired into our DNA according to some theorists.  Absence of nature is a contributory factor in the higher levels of stress and mental illness in cities. It could even explain why so many of us choose to take our holidays by the sea.

Research shows that modern humans prefer savannah type landscapes. This is explained because early hominids evolved in a savannah habitat, often by lakes (Leakey 1980). It is typified by spatial openness, scattered trees or small groupings of trees, and relatively uniform grassy ground surfaces.

Savannah provides higher food sources than rainforest, fewer phobic inducing creatures such as snakes and spiders, more open viewing for seeing predators. Lakes are ideal as sources of freshwater, animals to hunt, and protein rich crustacean food.

Hundreds of international studies in the past 20 years (for a review eg Kaplan and Kaplan 1989 above) show that modern people prefer elements of green vegetation, flowers, and water, compared with concrete and glass  The preferred landscape, across many cultures, is openness, smooth or uniform grassy vegetation, scattered trees or small groupings of trees, ie a forest setting with savannah or park like qualities. Natural settings with water are particularly attractive; young children show particularly positive responses to water. Images of threatening water eg stormy seas or clearly visible pollution are exceptions. Low preferences are also found for restricted depth of view, rough ground textures that obstruct movement, and dense impenetrable vegetation. Unimpressive natural scenes are even preferred to attractive urban landscapes lacking nature. Although introducing trees and associated vegetation greatly increases preferences for urban scenes. The attraction to savannah type surroundings is probably a mix of genetic and learned preferences.

From an evolutionary view early people would be concerned about and on the look out for predators, and also a ready supply of food and water. Feeling safe using these criteria would be important. If an early human was chased by a predator and managed to escape, by say climbing a tree, the flight response would be experienced as fear, anxiety and physiological changes such as increased heart rate and more rapid breathing. Once the danger had passed it would be important to recover as quickly as possible in order to continue searching or food and water, and find other people to be with. Knowing that the area you were in was rich in food and water would be reassuring and being able to search the landscape for people and predators, compared to looking at dense vegetation, would help recovery.

There is now a lot of convincing research to show that leisure activities in natural surroundings are important for people recovering from stress as well as meeting other needs. From evidence of over 100 studies, people involved in outdoor recreation talk about relaxation and peacefulness with regards to savannah like settings that show water, open space, and scattered and or large trees as being a key factor. Similar results come from studies of peoples’ responses to parks among urban settings. People in San Francisco were asked what settings they went to when stressed or depressed. 75% chose outdoor places that were natural environments or urban places dominated by natural elements such as parks, views of natural landscape, lakes and ocean.

Citation

Ulrich RS ‘Biophilia, Biophobia, and Natural Landscapes’ 73-137p in Biophilia Hypothesis ed Kellert SR and Wilson EO 1993 Island Press Washington.
Ulrich RS, Dimberg,U and Driver BL 1991 “Psychophysiological Indicators of Leisure Benefits.” in Benefits of Leisure, ed Driver BL, Brown PJ, and Peterson GL. State College, Pa:Venture

Mood & self esteem improves outdoors

Spending even a short amount of time in nature has a positive effect on our emotions. We can feel less depressed, less anxious and the experience can reduce levels of anger. Being in nature not only reduces stress it can make us feel better about ourselves and strengthen our immune system to fight disease.

Mental health cost the UK £77 billion a year and at any one time 16% of the population are diagnosed with a mental disorder. 5 million of us are stressed in the workplace and the effect on GDP is a 10 % drop in expected productivity. On economic grounds alone it makes sense to encourage people to make lifestyle changes that will improve their mental health, such as walking in the park. Much could be done to alleviate stress, depression and other forms of mental illness if we all spent more time in nature. There is now clear evidence that contact with a green environment reduces stress, enhances mood and improves self esteem. Some of the results from key research are summarised in the paper cited here. Many studies have recorded improvements in self esteem and mood from spending time in green areas. Low self esteem is related to poor performance in school, suicide, alcohol abuse, and mental illness in young people. Long term mood states of anger and fear are linked to physical diseases such as heart disease, strokes, rheumatoid arthritis, asthma, and vulnerabilities of the immune system.

Citation

Pretty J, Angus C, Bain M, Barton J, Gladwell V, Hine R, Pilgrim S, Sandercock S and Sellens M. 2009. Nature, Childhood, Health and Life Pathways. Interdisciplinary Centre for Environment and Society Occasional Paper 2009-02. University of Essex, UK.

Viewing nature heals the body

Professor Roger Ulrich was interested in the effects of different environments on patient recovery. He went to a suburban hospital in the USA and collected records over a 9 year period from wards where patients were recovering from having their gall bladder removed. He didn’t tell staff exactly what he was doing in case it biased the results, but he asked for records of how long patients took to recover, how much pain killers they required and how often they required staff attention. He matched people according to various criteria such as age, sex, weight, smoking/nonsmoking, floor, etc.. Some patients had a view of a tree from their bedroom window and others could only see a brick wall. He found significant differences between the two groups.

Patients with a view of greenery needed less staff attention, took fewer and milder pain killers, and they recovered on average a day earlier. They had fewer negative comments in their notes, eg ‘patient felt more chirpy this morning’.

The explanation offered is that being in hospital recovering from an operation is stressful and that being able to view nature had a calming effect, reduced stress and in turn aiding the body’s recovery.

Ulrich and associates have done other similar work. They have shown that a view of trees and green space makes the office environment a more positive place and that students revise better if they can see trees.

Citation

Ulrich R S. 1984. View through a window may influence recovery from surgery. Science 224, 420-21

Citation

Frumkin H. 2001. Beyond toxicity. human health and the natural environment. American Journal of Preventative Medicine 20 (3), 47-53
Fredrickson L M and Anderson D H. 1999. A qualitative exploration of the wilderness experience as a source of spiritual inspiration. J. Environ. Psychology 19, 21-39
both in
Green Exercise: Complementary Roles of Nature, Exercise and Diet in Physical and Emotional Well-Being Implications for Public Health Policy Jules Pretty1, Murray Griffin2, Martin Sellens2, Chris Pretty3 CES Occasional Paper 2003-1, University of Essex March 2003

Wilderness experiences are good but not essential

Many studies have shown a lasting positive effect of spending time on a wilderness programme. For example improvements in self esteem and a having a sense of purpose. One study of two groups of women in the USA showed the importance of individual contact with nature and sharing experiences with others.

“It was so incredible being able to hear the birds…. Just the crunching of animals all around us… The sounds of the forest, the snapping of twigs, hearing the tiny sigh of the wind through the treetops at night.”

“I noticed more, I felt more. I felt more connected to myself and even to other people on the trip.”

“I can’t even fully capture in words what happened to me when I was out there… It’s like the spirit is burning deep inside me again, and I’m looking at my life a little differently.”

“Instead of sitting back and observing it [the landscape], it’s like Iwas moving into it… some way, or rather it was moving into me. I couldn’t deny its effect on me.”

Source: Fredrickson and Anderson (1999)

The good news for those of us in cities is that other work has shown that the major difference in positive mental state is made by moving from a concrete urban world to a green environment such as a park. Experiences of wilderness have marginally more effect and may even generate feelings of loss and regret on return to the city.