Can Natural and Virtual Environments Be Used To Promote

As was alluded to earlier, Attention Restoration Theory has been built upon evidence that time spent in natural outdoor environments powerfully assist...
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Can Natural and Virtual Environments Be Used To Promote Improved Human Health and Wellbeing? M. H. Depledge,† R. J. Stone,*,†,‡ and W. J. Bird† †

European Centre for Environment and Human Health, Peninsula College of Medicine and Dentistry, Universities of Exeter and Plymouth, Knowledge Spa, Truro, Cornwall, TR1 3HD, U.K. ‡ Human Interface Technologies Team, University of Birmingham, B15 2TT, U.K.

’ INTRODUCTION When the Harvard biologist E.O. Wilson put forward the “Biophilia” Hypothesis, he captured a notion that has long been embedded in diverse cultures around the World.1 Briefly, the idea is that throughout evolutionary history humans have lived in intimate contact with nature. As a result we subconsciously seek connections with all that is alive and vital. This is particularly evident when life becomes difficult. Few individuals who have experienced stress of one form or another can have failed to have found some comfort in spending even a short time taking a stroll on a seashore, or sitting by a river, or walking in a forest, or even spending some quiet moments in a park. We need contact with nature (which in the context of this Feature refers to natural environments including green spaces in urban settings). The fact that we value natural environments is reflected in the choices we make. For example, Luttik 2 reviewed house prices across several districts of The Netherlands and concluded that people were prepared to pay between 8 and 12% more for houses with views of natural water scenes. Other research looking at restorative environments suggests that exposure of individuals to natural settings promotes stress reduction.3,4 Time spent in nature outdoors also assists the recovery of attentional capacity and cognitive function following intense mental activity, or fatigue brought on by “directed attention”.5 8 A restorative natural environment can be as simple as a window view out onto a garden. This is effective in reducing both postoperative recovery periods and the need for administration of pain-relieving analgesics.9 Recently, Lechtzin et al.10 have suggested that exposure to natural views and sounds can help to reduce the pain experienced by cancer patients undergoing bone marrow aspiration and biopsy. Other authors have attempted to demonstrate the human desire for connections with nature by showing test subjects photographs of urban and green environments and asking them to express their preferences for different scenes. For example, Kaplan,4 and Kaplan and Austin11 used black and white r 2011 American Chemical Society

photographic images to explore the role of vegetation in contributing to the satisfaction of living in particular homes. Participants in the study preferred scenes that were predominantly nature views. The presence of trees was strongly associated with feelings of relaxation. Similarly, views of gardens, flowers, and landscaped areas were highly favored. Several other studies (reviewed by Pretty and Barton12) show similar preferences. However, study designs have often been subject to bias. White et al.13 pointed out that image content (e.g., the presence of people, animals, etc.) was not always standardized. Some studies included people in urban scenes, but not nature scenes.14 16 Expressing a preference for natural environments might therefore reflect a liking for an environment with either few or no people, rather than for green space per se. Elsewhere, the issue has been avoided by only including scenes without people and animals.17,18 This discussion highlights the difficulties of investigating why nature means so much to us.

’ LEAVING NATURE Over the last 100 years, our increasingly urban lifestyles (ca. 75% of the European population now live in cities and towns19) have disconnected us from nature and this may have contributed to a decline in many aspects of our health and wellbeing. The UK Department of Health reported that children now spend only 9% of their time outdoors, while for adults the figure is approximately 20%.20 Indoor lifestyles are often associated with reduced exercise, increasing rates of obesity and diabetes,21 leading to higher incidences of depression and other psychiatric disorders. Estimates of the cost to the UK National Health Service (NHS) of reduced physical activity are £1 2 billion per annum21 (this equates to $1.6 3.2 billion per annum; date of conversion March 26, 2011). The Biophilia Hypothesis has yet to be subjected to rigorous scientific analysis, and there may well be other reasons for the increasing incidences of some of the disorders mentioned above. However, a weight of evidence is accumulating that natural environments have an important influence on our lives.21 Time spent in nature affects levels of physical activity resulting in reduced health service costs21 and also in the number of individuals claiming to have experienced the personal benefits of spending time in forests, on seashores, on river banks, mountains, or moorland. Barton and Pretty13 explored the dose response relationship between humans and natural environments. Exercise in the presence of nature (so-called green exercise) leads to positive short- and long-term health outcomes. Their meta-analysis of Published: April 19, 2011 4660

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Environmental Science & Technology 10 UK studies involving 1252 participants looked at ways of improving self-esteem and mood. Dose responses for both intensity and duration of exercise were regarded as showing large benefits from short engagements in green exercise, and then diminishing, but still positive returns for longer engagements. Every type of green environment improved both self-esteem and mood, and the proximity to water generated even greater effects. The greatest changes occurred in the young, with diminishing effects with age. The mentally ill exhibited some of the greatest selfesteem improvements. Although Barton and Pretty’s study13 is valuable, the data are characterized by very marked interindividual variability in responses leaving significant uncertainty about the robustness of general conclusions. For example, although sex differences in improvements were not evident in self-esteem after green exercise, men alone exhibited improvements in mood. Gender differences in health have recently been shown by others to be associated with exposure to natural environments.22 In a sample of 6432 urban wards, with a total population of 28.6 million adults aged 16 64 years in 2001, selected health outcomes that were plausibly related to greenspace (cardiovascular disease mortality, respiratory disease mortality, and self-reported limiting long-term illness) and another that was expected to be unrelated (lung cancer mortality). Male cardiovascular disease and respiratory disease mortality rates decreased with increasing exposure to greenspace, but no significant associations were found for women. Richardson and Mitchell 22 concluded that possible explanations for the observations were gender differences in perceptions and usage of urban greenspaces. This is but one example of interindividual differences in responses to exposure to nature. Clearly, there is still much to learn. Interestingly, there is supportive evidence from lower animals that removal from contact with nature is detrimental to their wellbeing. For example, ecotoxicologists have long known that it is very difficult to hold a wide variety of species in the laboratory as test organisms, simply because they do not flourish when removed from their natural habitats. This happens despite our best efforts to provide suitable food and living conditions and explains why only robust, common animals (for example, water fleas and sheepshead minnows) are used in regulatory toxicity testing rather than more sensitive, less common, but more typical species.23

’ NATURE IN OUR LIVING SPACES Globally, more and more people are living in cities. Also, over the last 20 years, fewer people have been visiting the countryside. This makes it especially important that towns and cities include within their precincts opportunities to come into contact with areas rich in vegetation (green spaces) and aquatic environments (rivers, canals, ponds, lakes, the sea coast—so-called blue spaces). A U.S. study in Philadelphia suggested that maintaining city parks could achieve yearly savings of approximately $69.4 million in health care costs.42 Given the renewed interest of several national governments in reducing the health costs associated with illness in their populations (see Department of Health report21 ), it seems timely that we initiate new research to determine just what characteristics of natural environments are beneficial to humans. Improved understanding could also be helpful to those who, for one reason or another, do not have easy access

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to nature; in particular, the elderly and infirm who spend almost all of their time indoors.

’ UNDERSTANDING HOW NATURAL ENVIRONMENTS CAN BE USED TO PROMOTE BETTER HEALTH There already exists a quite extensive literature regarding opportunities to use nature to promote health and wellbeing. Much of the work is anecdotal however, or involves small-scale studies, often lacking appropriate controls or statistical robustness. There are exceptions though. As was alluded to earlier, Attention Restoration Theory has been built upon evidence that time spent in natural outdoor environments powerfully assists recovery from mental fatigue.5,24 Work of this kind has led others to instigate programs that facilitate contact with, and physical activity within, natural environments as a way of tackling major disease issues such as obesity-related diabetes and depression, as well as improving general health and wellbeing. Bird25 reviewed the literature and identified evidence that time spent in natural environments was beneficial for improving mental health in people of all ages, improving self-discipline in children, helping the treatment of attention deficit hyperactivity disorder, reducing aggression and crime, promoting better health in the elderly, and delaying the impact of Alzheimer’s disease. Practical measures that take advantage of this knowledge include, for example, the Green Gym program that was initiated in 1997 with a view to encouraging people to become more active by engaging in gardening or conservation activities.26 The Green Gym Web site43 offers a “virtual green gym” tour to introduce the program. More recently, this approach was adapted to launch the Blue Gym program.44 Here, activities in the coastal marine environment ranging from mild activity associated with rock pool rambles and coastal walks, to more vigorous pursuits such as swimming, sailing, kayaking, and surfing, are being used to motivate people to spend more time outdoors engaging in physical activity. The Blue Gym has built into its operating structure rigorous scientific research led by the Peninsula College of Medicine and Dentistry (Universities of Exeter and Plymouth, UK) to ensure that changes in health and wellbeing can be assessed objectively.27 Elsewhere, research by Tsunetsugu and colleagues from the Japanese Forestry and Forest Products Research Institute has addressed the exposure of subjects to forest and urban settings and the effect that these exposures have on subjective ratings and physiological measures, including blood pressure, heart rate, and salivary cortisol excretion.28,29 Their studies demonstrated that 15 20 min exposures to natural environments, such as a broadleaf forest, were accompanied by significant lowering of blood pressure, pulse rate, and cortisol levels when compared to similar exposures in a busy city area. Subjective ratings of “calm”, “comfortable”, and “refreshed” were higher in forest conditions than those recorded in the city. Others have also recorded reductions in blood pressure30 and cortisol31 following time spent in natural environments. Such studies suggest that a reduction in symptoms related to prolonged stress and depression can be achieved, including those brought about by long periods of bad weather and annual time changes—forms of “constrained restoration”. There are numerous other examples. Watching animal movement, admiring flowers and trees, listening to birds and other outdoor sounds, viewing spectacular cloud formations or sunsets, and the familiar natural odors are among 4661

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the diverse attributes of nature that in some way promote wellbeing.25 But what mechanisms are involved?

’ CUES AND CLUES FROM A VIRTUAL WORLD Few researchers have attempted to identify the cues and clues that we pick up from natural environments that lead to better health and an improved sense of wellbeing. What are the signals that we respond to in nature that help us to relax and destress? Contenders include the colors that predominate in outdoor natural settings (greens, blues, browns), the sounds (bird song, trickling water, breaking waves, the wind in the trees), the odors of nature (the scent of flowers, the smell of wet grass and animal dung), air movement, light intensity, humidity, or a combination of these. Water is a particularly important trigger. Once again using a study based on choice of accommodation, Lange and Schaeffer32 reported findings for rooms in two hotels in Zurich. In one, room rates overlooking the lake were sustainable at roughly 10% more than those with views to a forest, confirming our preferences. Information of this kind prompted White et al.13 to look in greater depth at this issue. They showed subjects images of either urban or natural settings containing water to different degrees. This work revealed a strong “exposure-response” relationship. The more water that was evident in the photographs, irrespective of whether the images were of urban or natural settings, the more attractive they were to the observers.13 ’ VIRTUAL ENVIRONMENTS Another novel approach for identifying the stimuli we receive from nature involves the use of computer-generated forms of reality. Advances in hardware design and software toolkits have permitted the generation of extremely realistic virtual environments. A visit to the cinema to see computer-generated imagery in Hollywood blockbusters, such as Avatar (2009) or Inception (2010), or time spent playing a contemporary computer game, highlight the feasibility of creating new worlds in which to immerse ourselves. Indeed, the computer gaming community has contributed significantly to a resurrection of interest in the design and study of high-fidelity, ambience-rich virtual environments, courtesy of the development of affordable, real-time graphical computing technologies, together with software toolkits, many of which are available free of charge from the Web. Unlike nature, today’s software engineer has the possibility of controlling nearly every aspect of the virtual environment, from the color and movement of grass or the leaves on the trees, to the height of waves crashing on seashores or the abundance of wildlife in the scene. Early workers used cumbersome headmounted displays and other forms of wearable technologies, and even large-scale display enclosures (e.g., Cave Automatic Virtual Environments, or “CAVEs”) in attempts to recreate a sense of “immersion” in virtual worlds.33 However, the virtual reality (VR) decade from 1991 to 2001 demonstrated convincingly that immersive VR technologies were far too cumbersome, unreliable, and expensive to be exploited in real-world applications. That same decade also demonstrated that it is not technology per se that is responsible for achieving immersion in virtual environments. The design of appropriate and effective content—based on knowledge of human behavior in relation to the task—is by far the most critical issue in securing a sense of engagement or immersion.34 Recent technical developments are encouraging in respect of exploiting multiple human senses in virtual

Figure 1. Virtual reconstruction of country path with foliage.

environments, but we may have to wait several decades before technology provides truly immersive, multisensory, and believable worlds, along the lines of the Star Trek “Holodeck”. Despite current constraints, it is now possible to present the observer with strong visual and auditory impressions of the outdoors. For example, the power of today’s “serious games” toolkits,35 are, without doubt, providing virtual environment developers with the capabilities not only to model high fidelity and engaging 3D virtual rural and coastal scenes (Figure 1), but also to endow those scenes with dynamic natural processes, such as the diffusion of sunlight through foliage, motion of trees and plants in response to virtual wind, reflection and refraction inherent with virtual water, accurate seasonal lighting conditions, and much more. Unlike the situation that existed well over a decade ago, these graphical toolkits no longer necessitate highly expensive “supercomputers”, but can deliver detailed virtual worlds on low-cost laptops, even portable media devices such as Apple’s iPad or iPhone/iTouch platforms. Interactive display technologies are also improving. Where once a “window-on-theworld” display (similar to that featured with a mountain-and-lake scene in the science fiction film Total Recall [1990]) would have been prohibitively expensive for deployment in clinics or care homes modern, 50-in. flat-panel TV monitors can be adapted to respond to viewer head and body movement, with the on-screen images being tracked in real-time by, for example, a modified Nintendo Wiimote controller or other form of body tracking system such as Microsoft’s Kinect. Software toolkits emerging from the mainstream gaming community clearly demonstrate the power of immersion and engagement through the ability to deliver appropriate and convincing levels of fidelity relevant to the needs of the end user population. As was indicated earlier, visual cues and clues are only part of the story. Being in natural environments exposes us to a wide range of stimuli detected by our other senses including touch and force (haptics), changes in temperature, smell, air movements, and altered humidity. For example, Barfield and Danas36 pointed out that olfactory information has been largely ignored as input to the virtual environment participant, in spite of the fact that olfactory receptors provide an extremely rich source of information. One of the prime reasons for this has been the lack of availability of applications until quite recently, with new interest coming from the defense and medical communities. Cater37 4662

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Figure 2. Experimentation with wearable psychophysiological sensors to assess participant engagement and arousal.

identified ambient smells from a physical environment as being key to creating a sense of presence in a virtual environment. Recent developments in generating synthetic smells, from systems supporting therapies for post-traumatic stress disorder,38 to others developed for NASA (providing “steak, hot metal, and motorbike welding” smells, characteristic of working in space), have led to more compact technologies, suitable for PC control and integration with virtual or games-based environments. Present-day technologies, such as HeadHunter 2000's ScentPalette, or the recently announced ScentScape system by Scent Sciences, are examples of smaller-scale devices that have evolved over a number of years, from Sensorama in the 1960s (see Rheingold39), through entertainment devices in the 1980s, to a variety of false starts and failed attempts in the early 2000s (see Kortrum40). While research continues into creating the sense of actually being in virtual and games-based worlds, achieving and manipulating ambience in virtual environments is a new and seemingly untouched area of research. Ambience undoubtedly contributes to a sense of engagement, but the sensory factors involved have not been elucidated in any detail. Little is known about how to exploit vision, sound, smell, or touch or thermal factors, individually, or as integrated phenomena, to create credible and believable ambient effects in virtual contexts. Another complex issue is how to measure the impact of synthetic ambience on the engagement and psycho-emotive responses of the human user, over and above the standard use of subjective measures such as state-trait anxiety or mental workload questionnaires. Certainly it is possible to conduct the cortisol sampling mentioned earlier in the context of evaluating well-being and stress levels in green urban environments. However, virtual environments, by virtue of the ability of their designers to be able to vary subtle features of the simulation, demand more of a multivariate approach to the measurement of engagement. We are ignorant of how subtle changes in these features, or the removal of certain sensory effects from an environment (“de-integration”), are perceived by simulation users and what effects these may have on performance, engagement and, indeed, well-being. To address this, research is in progress in our laboratories (Figure 2) that is attempting to integrate and time-stamp psychophysiological measures of differing response latencies— galvanic skin response (GSR), heart

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rate, pupillometry, eye tracking, and electroencephalography (EEG)—to evaluate the effects of varying the sensory fidelity of virtual restorative environments. We have constructed the first two virtual restorative environments to support our experimental studies. These are based on the South Devon Coastal Path between Heybrook and Wembury Bays, just east of Plymouth (UK) and Burrator Reservoir, located within the Dartmoor National Park, just north of the same city. The coastal area is a sensorily rich, biodiverse marine conservation site and was chosen in conjunction with colleagues from the National Marine Aquarium, also based in Plymouth. The region consists of land owned by the National Trust, including the famous Great Mew Stone Island and the now-abandoned site of the Royal Navy gunnery range of HMS Cambridge (interestingly, this facility was successfully replaced in 2001 by a VR training installation at another land training facility, HMS Collingwood near Portsmouth41). Both the Burrator region and the coastal path, part of which is shown onscreen in Figure 2, are being recreated by the University of Birmingham using Unity, a powerful game and interactive media development tool. By exploiting established simulation design and fidelity knowledge,35 the research team is attempting to achieve a close match between the virtual and the real. To do this, Digital Terrain Model (DTM) data and aerial photographs have been imported into the Unity toolkit and both natural features and manmade artifacts have been added using custom-built or Websourced 3D models, including wild flowers, trees, hedgerows, fences, seating benches, and buildings. High-quality digital oceanic, coastal, and birdsong sounds have also been integrated. Yet another environment, based on a typical town center, but including a quiet park area with lake, has been developed for comparative investigations of urban and rural settings using subjective measures and the psychophysiological sensing techniques mentioned above. This pilot study, part of a Virtual Restorative Environment Therapy (VRET) initiative, is also supporting efforts to establish how those same psychophysiological indices can be used as part of a real-time biofeedback system whereby the participants’ arousal levels are directly linked to dynamic features of the virtual environment, such as cloud cover, weather, wave strengths, ambient sounds, and scents.

’ CONCLUSIONS Progress in the areas discussed above will improve our understanding of the interconnections among the environment, human health, and wellbeing. The value of natural settings in promoting health and the use of virtual environments to provide understanding of the mechanisms involved are important new areas of scientific investigation. The evidence that emerges will help us to determine how outdoor health programs might be optimized for maximum health benefit and also provide the scientific underpinning to make the case for their use as alternatives to pharmaceutical interventions alone. At present, the medical establishment has been reluctant to adopt such measures for want of such evidence. Virtual environments create the possibility of dissecting out at least some of the stimuli we receive from being outdoors in nature and ranking their relative importance. For those unable to enter freely into natural ecosystems, an improved understanding of the cues and clues we receive may eventually allow us to provide access to simulations of the natural world. Virtual environments could benefit the elderly or infirm actually within their homes or care units, and could be deployed within defense medical establishments to benefit those with physical and psychological trauma returning 4663

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Environmental Science & Technology from operations in conflict zones. Looking further ahead, the wellbeing of others removed from nature, such as submariners and astronauts confined for several months in their craft, might also be enhanced. Once the research has been conducted and appropriate software written, the provision of artificial environments is likely to become readily affordable and of widespread use to our health services. Perversely though, it could also reinforce the trend for spending less and less time outdoors. Such an outcome is precisely the opposite of the intention of most health care professional and environmental scientists. Fortunately, natural ecosystems are accessible to the majority of the population. Nature is easily available to the able-bodied, even in the heart of cities, and this trend is increasing as organizations such as the UK conservation agency “Natural England”, strive to ensure that accessible green spaces fall within 300 m of every home. This dilemma highlights lifestyle choices and to some extent moral and ethical issues. Humans are a mammalian species that has evolved along with all other species. We are part of nature. It can be argued that as well as the pleasure that nature affords, we have a responsibility to maintain our intimate connections with other species and indeed that we should reconnect with nature to understand, appreciate, and support it to the fullest degree. Sustainable development involves maintaining a balance within ecosystems; a balance in which we do not overexploit the resources of the planet. In return we obtain ecosystem services, notably food, fresh water, and clean air, and, less obviously, the benefits of outdoor exercise, aesthetic stimulation, and the profound sense of wellbeing that Nature alone can deliver to us in her myriad forms.

’ AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected].

’ BIOGRAPHY Prof. Michael DePledge is Chair of the Advisory Board of the European Centre for Environment and Human Health and Professor of Environment and Human Health at the Peninsula College of Medicine & Dentistry in Plymouth. A former member of the UK Government’s Chief Scientific Advisor’s Committee, Michael is also Chairman of the Science Advisory Committee on the Environment and Climate Change, of the European Commission in Brussels. He also served as the Chief Scientific Advisor of the UK Government’s Environment Agency from 2002 to 2006. Professor Bob Stone holds a Chair in Interactive Multimedia Systems at the University of Birmingham (UK). He is Research Director of the UK Human Factors Integration Defence Technology Centre and an Academician of the Russian International Higher Education Academy of Sciences. A multiple award-winning Chartered Psychologist, Bob is involved in numerous international projects specialising in the application of human factors knowledge to the design and evaluation of virtual defense, healthcare and heritage technologies, simulation and advanced robotics. Dr William Bird is the strategic health advisor for Natural England, leading the health program to develop the natural environment as a major health resource. He chairs the Outdoor Health Forum that unites all major UK environment organisations to influence health professionals to use the natural environment for prevention and treatment. William has recently become the Clinical Director of the Environment and Human Health Unit at the Peninsula College of Medicine & Dentistry.

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’ REFERENCES (1) Wilson, E. O. Biophilia: the Human Bond with Other Species.: Harvard University Press, Cambridge, MA. 1984. (2) Luttick, M. The value of trees, water and open space as reflected by house prices in the Netherlands. Landscape and Urban Planning 2000, 48, 161–167. (3) Ulrich, R. S. Nature versus urban scenes: some psychophysiological effects. Journal of Environment and Behaviour 1981, 13, 523–556. (4) Kaplan, R. The nature of the view from home. Journal of Environment and Behaviour 2001, 33, 507–542. (5) Kaplan, R; Kaplan, S. The Experience of Nature: A Psychological Perspective.: Cambridge University Press: Cambridge, NY, 1989. (6) Kaplan, S. The restorative benefits of nature: toward an integrative framework. Journal of Environmental Psychology 1995, 15, 169–182. (7) Berto, R. Exposure to restorative environments helps restore attentional capacity. Journal of Environmental Psychology. 2005, 25, 249–259. (8) Berman, M. G.; Jonides, J.; Kaplan, S. The cognitive benefits of interacting with nature. Psychological Science 2008, 19, 1207–121. (9) Ulrich, R. S. View through a window may influence recovery from surgery. Science 1984, 224, 420–421. (10) Lechtzin, N.; Busse, A. M.; Smith, M. T.; Grossman, S.; Nesbit, A.; Diette, G. B. A randomized trial of nature scenery and sounds versus urban scenery and sounds to reduce pain in adults undergoing bone marrow aspirate and biopsy. Journal of Alternative and Complementary Medicine. 2010, 16(9): 965-972. doi:10.1089/acm.2009.0531 (11) Kaplan, R.; Austin, M. E. Out in the country: sprawl and the quest for nature nearby. Landscape and Urban Planning 2004, 69, 235–243. (12) Barton, J.; Pretty, J. What is the best dose of nature and green exercise for improving mental health? A multi-study analysis. Environ. Sci. Technol. 2010, 44 (10), 3947–3955. (13) White, M. P.; Smith, A.; Humphries, K.; Pahl, S.; Snelling, D.; Depledge, M. Blue space: the importance of water for preference, affect and restorativeness ratings of natural and built scenes. Journal of Environmental Psychology. 2010in press. (14) Hartig, T.; Staats, H. The need for psychological restoration as a determinant of environmental preferences. Journal of Environmental Psychology 2006, 26, 215–226. (15) Staats, H.; Hartig, T. Alone or with a friend: A social context for psychological restoration and environmental preferences. Journal of Environmental Psychology 2004, 24, 199–211. (16) Ulrich, R. S.; Simons, R. F.; Losito, B. D.; Fiorito, E.; Miles, M. A.; Zelson, M. Stress recovery during exposure to natural and urban environments. Journal of Environmental Psychology 1991, 11, 201–230. (17) Herzog, T.; Maguire, C.; Nebel, M. Assessing the restorative components of environments. Journal of Environmental Psychology 2003, 23, 159–170. (18) Felsten, G. Where to take a study break on the college campus: An attention restoration theory perspective. Journal of Environmental Psychology 2009, 29, 160–167. (19) RCEP . The urban environment; Royal Commission on Environmental Pollution 26th report, published by TSO, London, 2007, 218pp. (20) HPA, (Health Protection Agency). Health effects of climate change in the UK 2008; Health Protection Agency, UK, 124pp. 2008. (21) DH (Department of Health). Be active, be healthy; Department of Health, HM Government, London, 72pp, 2009. (22) Richardson, E. A.; Mitchell, R. Gender differences in green space and health relationships in the United Kingdom. Social Science & Medicine 2010, 71, 568–575. (23) Sprague, J. B. Measurement of pollutant toxicity to fish I. Bioassay methods for acute toxicity. Water Res. 1969, 3 (11), 793–821. (24) Kaplan, R., Kaplan, S., Ryan, R. L. With People in Mind: Design and Management of Everyday Nature. Washington, DC: Island Press; 1998. 4664

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(25) Bird, W. J. Natural thinking; Royal Society for the Protection of Birds, 2007, 116pp. (26) Bird, W. J. Natural Fit; Royal Society for the Protection of Birds. 2004, 96pp. (27) Depledge, M. H.; Bird, W. The Blue Gym: health and wellbeing from our coasts. Mar. Pollut. Bull. 2009, 58, 947–948. (28) Tsunetsugu, Y.; Park, B.-J.; Ishii, H.; Hirano, H.; Kagawa, T.; Miyazaki, Y. Physiological effects of Shinrin-Yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan. J. Physiol. Anthropol. 2007, 26 (2), 135–142. (29) Park, B.-J.; Tsunetsugu, Y.; Kasetani, T.; Hirano, H.; Kagawa, T.; Sato, M.; Miyazaki, Y. Physiological effects of Shinrin-Yoku (taking in the atmosphere of the forest) using salivary cortisol and cerebral activity as indicators. J. Physiol. Anthropol. 2007, 26 (2), 123–128. (30) Hartig, T.; Evans, G. W.; Jammer, L. D.; Davis, D.; Garling, T. Tracking restoration in natural and urban field settings. Journal of Experimental Psychology 2003, 23, 109–123. (31) Van den Berg, A. E. Restorative effects of nature: towards a neurobiological approach. Proceedings of 9th Congress of Physiological Anthropology 2006, 132–138. (32) Lange, E.; Schaeffer, P. V. A comment on the market value of a room with a view. Landscape and Urban Planning 2001, 55, 113–120. (33) Jennett, C.; Cox, A. L.; Cairns, P.; Dhoparee, S.; Epps, A.; Tijs, T.; Walton, A. Measuring and defining the experience of immersion in computer games. Int. J. Human-Computer Studies 2008, 66, 641–661. (34) Stone, R. J. Human factors guidelines for interactive 3D and gamesbased training systems design:edition 1. Human Factors Integration Defence Technology Centre Publication (www.hfidtc.com), 2008. (35) Stone, R. J. Virtual environments and human factors: a personal reflection on the last 30 years”; invited article for Ergonomics at 60: A Celebration; The Ergonomics Society; January 2009, 8 9. (36) Barfield, W.; Danas, E. Comments on the use of olfactory displays for virtual environments. Presence. 1995, 5 (1), 109–121. (37) Cater, J. P. The nose have it! Letters to the Editor. Presence 1992, 1 (4), 493–494. (38) Rizzo, A.; Rothbaum, B. O.; Graap, K. Virtual reality applications for the treatment of combat-related PTSD. In Combat Stress Injury: Theory, Research and Management.; Figley, C. R., & Nash, W. P. (Eds), Taylor and Francis Books: New York, 2006, Chapter 11, pp 183 204. (39) Rheingold, H. Virtual Reality.: Summit Books. 1991, 384pp. (40) Kortrum, P. (Ed.). HCI Beyond the GUI: Design for Haptic, Speech, Olfactory and Other Non-traditional Interfaces.: Morgan Kaufmann Publishers. 2008. 462pp. (41) Stone, R. J.; Rees, J. B. M.Application of virtual reality to the development of naval weapons simulators. In Proceedings of Interservice/ Industry Training, Simulation and Education Conference (I/ITSEC), 2002, 129-139. (42) Bird, W. J. Personal Communication 2010. (43) Green Gym Website; http://www2.btcv.org.uk/display/greengym (44) Blue Gym Website; www.bluegym.org.uk

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