Corey L.M. Keyes (ed.)Mental Well-Being2013International Contributions to the Study of Positive Mental Health10.1007/978-94-007-5195-8_11© Springer Science+Business Media Dordrecht 2013

11. The Nature of Happiness: Nature Affiliation and Mental Well-Being

Andrew J. Howell¹ and Holli-Anne Passmore¹

(1)

Department of Psychology, Grant MacEwan University, Edmonton, AB, Canada

Andrew J. Howell

Email: HowellA@macewan.ca

Abstract

It has been over 25 years since E. O. Wilson (Biophilia. Harvard University Press, Cambridge, MA, 1984) wrote Biophilia, in which he argued for an evolved inclination among humans to affiliate with nature. Psychologists have examined both restorative and additive effects of nature-related experiences on health and well-being. We review correlational and experimental studies showing associations between nature affiliation (or nature immersion) and positive markers of mental health. The research evidence converges on the conclusion that nature involvement is good for us. We discuss future lines of research concerning mediators and moderators of the relationship between nature and well-being, the role of technologically mediated nature experiences, and the development of nature-related interventions aimed at boosting well-being.

Appreciating the beauty of a blossom, the loveliness of a lilac, or the grace of a gazelle are all ways in which people can, in some small measure, fill their daily lives with evolutionarily inspired epiphanies of pleasure (Buss 2000, p. 22).

It has been over 25 years since E. O. Wilson (1984) wrote Biophilia, in which he argued for an evolved inclination among humans to affiliate with nature. Wilson reasoned that, because our ancestors’ survival and reproduction depended upon access to natural resources, selection pressures favored those who had an affinity to orient toward nature. Findings in support of Wilson’s biophilia hypothesis have emerged (Kaplan and Kaplan 1989; Ulrich 1993), including evidence for human preference for savannah-like landscapes, beneficial physiological responses to natural environments relative to manufactured environments, and improvements in cognitive functioning and restorative effects on mental well-being as a result of exposure to nature (see review by Joye 2007).

Additional support for Wilson’s (1984) idea that we have a deep-rooted connection to nature comes from the fact that only recently in our evolutionary history have we separated ourselves from a hunter-gatherer way of life which was immersed daily in nature (Burns 2005; Frumkin 2001; Gullone 2000; Kahn 1997; Kellert 1997; Nesse and Wiliams 1996). There is dissociation between human biology and modern urban life. As Gelter (2000) writes, “[t]he time-span in our habitat change from the natural world setting into the technological habitat is too short for the evolutionary processes to permit any major biological adaptations” (p. 86). Within this context, affiliating with nature is framed as a basic human need.

Unfortunately, humanity is increasingly neglecting this instinctual preference or need. In 1847, Emerson lamented that “[w]e do not know an edible root in the woods. We cannot tell our course by the stars, nor the hour of the day by the sun” (p. 249). In 2013, some 160-odd years later, our disengagement from nature is even more pronounced, widespread, and lamentable. The World Health Organization (WHO) announced in 2009 that more than half of the world’s population now lives in an urban, rather than rural, environment; WHO projects this will increase to 65% by 2030 (WHO, 2011). In Canada, for example, the 50% urbanization mark was passed in 1941, and today, more than 80% of Canadians live in urban areas (Human Resources and Skills Development Canada 2007). On average, Canadians spend almost 90% of their time indoors (Environment Canada 2005), and a Kaiser Family Foundation study (2010) reported that the average child (aged 8–18) in the United States spends over 7 h a day plugged into some form of entertainment media. Both time-criterion and nature-knowledge-criterion studies show that nature-based recreation is on the decline in many countries (Charles and Louv 2009; Pergams and Zaradic 2008). Terms such as nature deficit disorder (Louv 2005) and nature starvation (Royal Society for the Protection of Birds 2010) have been coined to reflect our increasing disconnection from nature. In a recent survey of 1,000 United Kingdom citizens, only 55% of those over the age of 35, and 37% of those under the age of 35, reported feeling “connected to the natural world” (Royal Society for the Protection of Birds 2010).

But, does this epoch of industrialization really matter? Are we, both individually and as a species, poorer because of this protracted divorce from nature? Evidence is mounting that answers these questions with a resounding “yes.” Nature affiliation and exposure to elements of the natural environment clearly, and significantly, impact our physical health and overall well-being in a positive manner.

We need the tonic of wildness. (Thoreau 1854/1989, p. 339)

In the last decade alone, several lines of inquiry have explored the relationship between physical health and engagement with, or proximity to, elements of the natural world. For example, Pretty (as cited in Mind 2007) found that green exercise—exercising while viewing photographs or pictures of nature—reduced blood pressure to a greater degree than did exercising in the absence of such photos or in the presence of less green rural or urban photos.

Takano et al. (2002) showed that longevity was greater among senior citizens living in areas with walkable green spaces. Five year survival rates for 3,144 Tokyo seniors, born in 1903, 1908, 1913, or 1918, were analyzed. Variables such as age, sex, marital status, socioeconomic status, and baseline physical ability were controlled. Having walkable green streets and spaces near the seniors’ residences showed significant predictive value for elderly survival over the 5 years of the study. It appears that character Carrie Watts (played by actress Geraldine Page), in The Trip to Bountiful, justly proclaimed, “I bet I can live to a hundred if only I can get outdoors again.”

Historical data concerning over 10,000 people in Holland was analyzed by de Vries et al. (2003) to explore the relationship between green space and health. Respondent information was used only if the degree of urbanism in their neighborhood had remained constant over the time period that the data had been originally collected and if respondents had lived in their current location for over 12 months. These two exclusion criteria left 10,197 respondents from 1,155 different neighborhoods. Three global health indicators were used: number of symptoms experienced in the past 2 weeks, perceived general health rated on a 5-point scale, and the Dutch version of Goldberg’s 1972 Global Health Questionnaire. Several demographic and socioeconomic variables were controlled, as was level of urbanism. A strong relationship between health and greenness of environment was shown; people living in a greener environment, regardless of level of urbanism, reported fewer physical symptoms and greater perceived general health. Of particular note, de Vries et al. found that “assuming a causal relation between greenspace [sic] and health, 10% more greenspace [sic] in the living environment leads to a decrease in the number of symptoms that is comparable with a decrease in age by 5 years” (p. 7). A subsequent study conducted by Maas et al. (2006) involved the review of records for 250,782 Dutch citizens being treated by 104 general practitioners; the relationship between health and green space was confirmed. Maas et al. reported that “health differences in residents of urban and rural municipalities are to a large extent explained by the amount of green space” in the individuals’ direct living environment (p. 591). Moreover, the relation between green space and health was found to be stronger for lower socioeconomic groups.

Similar findings emerged in a recent study by Mitchell and Popham (2008), which examined socioeconomic factors in relation to health inequalities and access to green space. In this study, mortality records for 366,348 individuals of the population of England at younger than retirement age were classified into groups based on income deprivation and exposure to green space. (Exposure to green space was calculated using England’s generalized land use database.) Based on the analyses of these data, Mitchell and Popham reported that “[p]opulations that are exposed to the greenest environments also have lowest levels of health inequality related to income deprivation” (p. 1655).

There was a great joy—to be out in the air—for I had not been outside in almost a month. […] Some part of me came alive […] which had been starved, and died, perhaps without my knowing it (Sacks, as quoted in Frumkin 2001, p. 236).

A sizeable body of accumulated research corroborates neurologist Oliver Sacks’ eloquent description of nature’s restorative effect on our well-being. Ulrich (1993), whose own work is seminal in this area, provided a summary of the proposed theoretical platform for the restorative capacity of our biophilic responses. Maller et al. (2005) provided a summary of substantiating research findings, including stress reduction after urban park or wilderness excursions; reduction in feelings of anger and aggression after viewing color photographs of nature scenes, as well as subsequent to viewing urban scenes with salient natural elements such as trees and other vegetation; and decreased postoperative anxiety among patients exposed to nature pictures depicting an open water view.

The Kaplans’ influential work (Kaplan 1993, 2001, 1995; Kaplan and Kaplan 1989), based on attention restoration theory (ART), has linked exposure to nature with restoration of stress and attentional fatigue, resulting in improved cognitive functioning and well-being. This body of work has provided additional empirical support for nature’s restorative effect. For example, office workers with a window view encompassing natural elements reported higher job satisfaction and fewer physical ailments than did office workers with a window view of urban scenes lacking natural elements (Kaplan 1993). Other researchers have also reported a positive effect on individuals’ cognitive functioning when tasks are performed in rooms with windows affording views of nature (see Chalquist 2009). Ulrich (as cited in Chalquist 2009) found that the introduction of flowers and plants into a workplace increased cognitive functioning, resulting in a reported “15% rise in innovative ideas and more creative, flexible problem-solving than that of the control group without greenery nearby” (p. 2).

Professionals in a variety of disciplines are beginning to investigate ways of utilizing these research findings by building exposure to nature into components of treatment plans for an array of diagnoses. For example, building on the Kaplan’s work with ART and exposure to nature, Taylor et al. (2001) explored the benefits of “greening” play areas as part of a treatment plan for children diagnosed with attention deficit disorder (ADD) or attention deficit/hyperactivity disorder (ADHD). In this study consisting of 96 parents of children aged 7–12 years diagnosed with ADD/ADHD, contact with nature was systematically related to a decrease in the children’s attention deficit symptoms—“the ‘greener’ a child’s play area, the less severe his or her attention deficit symptoms” (p. 54). Kuo and Taylor (2004) replicated these findings in a national study of 452 parents/guardians of children aged 5–18 years who had been diagnosed with ADHD. Regardless of age, gender, income, community type, and geographic region, findings were consistent: “green outdoor activities reduced [ADD/ADHD] symptoms significantly more than did activities conducted in other settings, even when activities were matched across settings” (p. 1580).

Therapeutic gardening, formalized as horticulture therapy, is used in a number of treatment settings, including community based programs, geriatric programs, prisons, developmental disabilities programs, and special education (Mattson, as cited in Frumkin 2001). One such setting is the healing garden at the Swedish University of Agricultural Sciences’ Alnarp campus (Grahn et al. 2007; Stigsdotter and Grahn 2003), designed specifically for use in a treatment program for individuals who have been unable to work or study for over 2 years due to “burnout” or depression. The treatment program runs 8 weeks, during which time patients interact with the therapeutic team (consisting of a horticultural therapist, a landscape architect, an occupational therapist, a physical therapist, a physician, and a psychotherapist) while working and spending time in the garden 3 h and 30 min a day, 4 days a week.

In his biophilia hypothesis, Wilson (1984) also suggested that we have an innate urge to affiliate with other forms of life; indeed, the subtitle of Biophilia is The Human Bond with Other Species. This bond between humans and animals is recognized by therapists and counselors in the emerging field of Animal-Assisted Therapy (AAT), wherein animals or pets are an integral part of the therapy program and help to engage the client in the therapeutic process (Fine, as cited in Wesley et al. 2009; Walsh 2009). Several studies have demonstrated that AAT enhances both the therapeutic relationship and positive therapy outcomes when used with diverse populations in a variety of therapy settings, such as psychiatric inpatients, substance abuse populations in residential group therapy, and couples and family therapy (Hooker et al. 2002; Marr et al. 2000; Walsh 2009; Wesley et al. 2009).

A few counseling psychologists, most notably George Burns (1998, 2009) and Ronen Berger (Berger and McLeod 2006), are incorporating elements of nature into their therapy work with clients who are struggling with issues involving relationship difficulties, chronic pain, autism, and depression.

[As] psychologists we have heard but little about gardens, about foliage, about forests and farmland. … Perhaps this resource for enhancing health, happiness, and wholeness has been neglected long enough. (Kaplan and Kaplan 1989, p. 189)

Most of the research thus far presented has focused on the reduction of dysfunction—be it stress, anxiety, anger, depression, substance abuse, or inattention. Mental health, however, is more than the absence of mental illness (Keyes 2005); therefore, we now expand our focus to look at not just the restorative, but also the additive, effects of nature. In line with this, nature affiliation has recently emerged as an interest within positive psychology. For example, in their classification of character strengths, Park et al. (2006) describe appreciating beauty and excellence as being related to nature involvement; Keltner and Haidt (2003, see also Shiota et al. 2007) include nature among the most common elicitors of the experience of awe; in their introduction to positive psychology, Gable and Haidt (2005) referred to exposure to green spaces (p. 104) as a potential means of boosting well-being; and Fredrickson (2009) lists find nearby nature as Tool 6 in her tool kit of proven strategies to increase one’s level of positivity (p. 177). Nonetheless, the role of nature affiliation in positive functioning is often overlooked (Herzog and Strevey 2008). We next examine evidence for such a role.

Measures of Nature Affiliation

Nature affiliation has been viewed as a trait, that is, as a stable disposition capturing important differences between persons. This trait has been defined as “individuals’ experiential sense of oneness with the natural world” (Mayer and Frantz 2004, p. 504). Nature affiliation has also been characterized as “dynamic, changing from day to day and moment to moment as a function of experiences with nature” (Weinstein et al. 2009, p. 1316) and can thus be conceptualized as a state. The recent development of reliable and valid measures of both trait and state conceptualizations of nature affiliation has significantly aided research on nature affiliation and positive indices of well-being.

The 14-item Connectedness to Nature Scale, developed by Mayer and Frantz (2004), assesses nature affiliation as a relatively stable disposition or trait. Items (e.g., “I often feel a sense of oneness with the natural world around me”; “Like a tree can be part of a forest, I feel embedded within the broader natural world”) assess a sense of oneness with the natural world and are rated on 5-point scales with endpoints 1 = strongly disagree and 5 = strongly agree. Total scores are calculated by summing across items after reverse-scoring oppositely worded items; higher scores denote greater nature affiliation. Mayer and Frantz reported a coefficient α of 0.84 and demonstrated that factor analysis consistently yielded a one-factor solution. Mayer and Frantz validated their measure in a series of five studies with both community members and university students by establishing a nomological web of positive and negative correlates (e.g., time spent outdoors, degree of environmental concern, endorsement of consumerism, and other explicit and implicit measures of nature connectedness). Scores on the scale are not related to social desirability, and no gender difference has emerged. The entire scale is included in the appendix of the article by Mayer and Frantz.

Recently, Mayer et al. (2009) created a 13-item version of the Connectedness to Nature Scale in order to assess the acute state of nature affiliation, which has proven to have good internal stability (coefficient α = 0.91). Items (e.g., “Right now I’m feeling a sense of oneness with the natural world around me”; “At the moment, I’m feeling that the natural world is a community to which I belong”) are rated on a 7-point scale with endpoints 1 (strongly disagree) and 7 (strongly agree). The state version was validated among three samples of undergraduate psychology students by evidencing positive associations with environmental self-awareness, private self-awareness, ability to reflect, and attentional capacity; and a negative association with public self-awareness. The state version of the Connectedness to Nature Scale is available in the article by Mayer et al. (2009).

The Nature Relatedness Scale is a 21-item scale developed by Nisbet et al. (2009), in order to assess individual differences in people’s “appreciation for and understanding of our interconnectedness with all other living things on the earth” (p. 4). Items (e.g., “I enjoy digging in the earth and getting dirt on my hands”; “I don’t often go out in nature”) are rated on a scale with endpoints 1 = disagree strongly and 5 = agree strongly. While factor analysis has suggested a 3-factor structure (i.e., internalized identification with nature, nature-related worldview, and familiarity with the natural world), an overall score is calculated by summing across all items, with higher scores denoting greater nature relatedness. The scale has good internal stability (coefficient α of 0.87) and good test-retest stability (0.85). The scale was validated by Nisbet et al. with undergraduate psychology students against related measures (e.g., ecology scales) and behaviors (e.g., buying organic food, choosing fair trade products, owning a pet, adopting vegetarianism, belonging to an environmental organization, participating in nature activities). Scores correlate positively with measures of extraversion, agreeableness, conscientiousness, and openness, as well as with measures of humanitarianism, love of animals, and considering future consequences of behavior. Among public and private sector executives, scores were shown to correlate positively with experience-sampling measures of time spent outdoors and in nature. This scale has been made available to researchers through contact with the scale developers.

Leary et al. (2008) devised a 16-item Allo-Inclusive Identity Scale, adopted from Aron et al.’s (1992) Inclusion of Other in the Self Scale (see also Schultz 2001, for a briefer such adoption). Eight items address the extent to which nature is incorporated into one’s identity, and eight items address the extent to which other people are incorporated into one’s identity (the latter scale is not discussed further here). Items (e.g., “The connection between you and the Earth”; “The connection between you and a tree”) are rated by choosing one of seven diagrams depicting increasing degrees of overlap between a circle labeled you and one labeled other. Leary et al. reported a coefficient α > 0.75 for the Nature subscale and generated preliminary evidence of the subscale’s validity (e.g., significant correlations with kindness, spirituality, and ecological concern; independence from socially desirable responding). The Allo-Inclusive Identity Scale is available within Leary et al.’s chapter.

Clayton (2003) described the content and validation of the Environmental Identity Scale, devised to assess the incorporation of the natural environment into one’s identity. This scale is composed of 24 items, such as “I really enjoy camping and hiking outdoors” and “Living near wildlife is important to me; I would not want to live in a city all the time.” Clayton established the internal reliability of the scale (coefficient α > 0.90 across three studies) and showed that scores on the scale correlate positively with proenvironmental behaviors and choices and with measures of ecocentrism and the value of universalism. Scale items appear in the appendix of Clayton’s chapter.

Finally, Diessner et al. (2008) constructed the Engagement with Beauty Scale, which is composed of a 4-item Natural Beauty subscale in addition to Moral Beauty and Artistic Beauty subscales (the latter two subscales are not discussed further here). Items (e.g., “I notice beauty in one or more aspects of nature”; “When perceiving beauty in nature I feel changes in my body, such as a lump in my throat, an expansion in my chest, faster heart beat, or other bodily responses”) are rated on a 5-point scale with endpoints 1 (very unlike me) to 7 (very much like me). As employed with a sample of undergraduate students, the subscale has adequate internal reliability (α = 0.80) and test-retest reliability (r = 0.79) and is inversely associated with materialistic values while directly related to both spiritual transcendence and gratitude (Diessner et al.). Items comprising the Natural Beauty subscale are presented in the appendix of Diessner et al.’s article.

Nature Affiliation and Well-Being

The pursuit of ‘the good life’ is through our broadest valuational experience of nature. (Kellert 1993, p. 60)

Commensurate with the development of reliable and valid measures of nature affiliation, the last decade has seen an increase in both correlational and experimental research linking nature affiliation with well-being. The correlational approach to examining nature involvement and well-being assesses the association between individual differences in nature affiliation and aspects of well-being (e.g., life satisfaction; positive affect; psychological, emotional, and social well-being.) A significant correlation between trait nature affiliation and life satisfaction was demonstrated in a study by Mayer and Frantz (2004) aimed at validating their dispositional Connectedness to Nature Scale. Diessner et al.’s (2008) Natural Beauty subscale of the Engagement with Beauty Scale was shown to correlate, among undergraduate students, with a measure of life satisfaction. However, Leary et al. (2008) did not find that life satisfaction correlated significantly with scores on the Allo-Inclusive Identity—Nature scale.

State (but not trait) nature affiliation was significantly associated with positive affect in three studies conducted by Mayer et al. (2009); in the second of these studies, state nature affiliation was also significantly inversely associated with negative affect. In one of their two studies, Nisbet et al. (2009) demonstrated a positive correlation between Nature Relatedness scores and scores on an extraversion measure (which includes a tendency toward positive affect).

The majority of correlational studies examining individual differences in nature affiliation and well-being have focused upon positive affect and life satisfaction. These studies, as presented above, have yielded mixed results. This mixed pattern of findings may be understandable in terms of the differences drawn by some theorists concerning hedonic versus eudaimonic aspects of well-being (Kashdan et al. 2008; Keyes and Annas 2009; Waterman 2008). Hedonic well-being refers to attaining pleasure or feeling well and is measured with indices of life satisfaction and positive affect. Eudaimonic well-being refers to functioning well in either the private or public domain (Keyes and Annas 2009). Eudaimonia is concerned with how one lives one’s life and thus focuses on concepts such as meaning, growth, and social relatedness; it is measured, in part, with indices of psychological and social well-being (Keyes and Annas 2009). It may be that aspects of well-being beyond hedonic positive affect and life satisfaction are most associated with nature affiliation. It is also possible that nature affiliation relates to some aspects of hedonic functioning (e.g., awe and vitality) more than others.

Howell et al. (2011) conducted two studies examining associations among various measures of nature affiliation and Keyes’ (2005) comprehensive measure of well-being, which assesses emotional well-being via ratings of positive affect and ratings of life satisfaction (e.g., Diener et al. 1999); psychological well-being via ratings of self-acceptance, positive relations with others, personal growth, purpose in life, environmental mastery and autonomy (Ryff 1989); and social well-being via ratings of social acceptance, social actualization, social contribution, social coherence, and social integration (Keyes 1998). In a first study with Canadian undergraduate psychology students, correlations between the Connectedness to Nature Scale and both psychological and social well-being were significant (albeit small in magnitude), whereas no relationship emerged with emotional well-being. In a second study with Canadian undergraduate psychology students, all three forms of well-being were significantly associated with three measures of nature affiliation: the Connectedness to Nature Scale, the Nature Relatedness Scale, and the Allo-Inclusive Identity—Nature scale.

Additional findings have emerged for the relationship between nature affiliation and eudaimonic aspects of well-being, such as personal growth, engagement, and meaning. Herzog and Strevey (2008) measured undergraduate students’ self-reported degree of contact with nature and correlated it with numerous indices of well-being. They showed that contact with nature was associated with positive affect and with the personal growth subscale of Ryff’s (1989) psychological well-being scales. In research expanding on their previous work, Nisbet et al. (2011) had undergraduate students (study 1) and government and business executives (study 2) complete the Nature Relatedness Scale, as well as measures of positive affect, life satisfaction, and psychological well-being. Nature relatedness was not significantly associated with life satisfaction, but was significantly associated with positive affect, autonomy, personal growth, and purpose in life. And in research conducted by Peterson et al. (2007), engagement and meaning aspects of well-being were reliable correlates of the character strength of appreciating beauty.

Famed naturalist John Muir (1901) encouraged us to “[c]limb the mountains and get their good tidings. Nature’s peace will flow into you as sunshine flows into trees. The winds will blow their own freshness into you, and the storms their energy…” (p. 56). Recent research provides empirical support for Muir’s notion that relating to nature is associated with greater feelings of vitality. Ryan et al. (2010) conducted (in addition to three experiments described below) two correlational studies examining associations between outdoor activity and subjective vitality. In study 4, undergraduate students completed a diary study in which they logged, on a daily basis, their level of vitality; they also recorded whether they spent more than 20 min outside, whether they exercised for more than 20 min, and whether they engaged in social interaction for more than 20 min. Participants were also paged at random times to record whether or not the activity they were engaged in took place outside, took place in a natural or artificial setting, involved social activity, or involved physical activity. Regardless of the influence of exercise and social activity, results showed that for diary measures, greater vitality was associated with spending more than 20 min outdoors. Similarly, paging measures revealed that, controlling for social, physical, and outdoor activity, behaviors involving nature predicted greater vitality. In study 5, undergraduate students completed a 4-day experience-sampling procedure in which they were paged randomly six times per day and recorded the number of people they were interacting with, the extent of their physical activity, whether they were indoors or outdoors, the presence of natural and non-natural environmental elements, and their subjective vitality. As in study 4, results showed that participants experienced greater vitality if they were exposed to nature and that simply being outdoors was not predictive of vitality if this did not involve contact with nature.

It appears that the cognitive aspect of relating to nature also has a vitalizing effect. In study 3 by Nisbet et al. (2011), students enrolled in a university course related to the environment were contrasted with students enrolled in non-environment-related courses. Results revealed that students in classes pertaining to the environment reported higher levels of vitality than did students in other courses. This higher level of vitality was accounted for by students maintaining a stronger sense of connectedness to nature (compared to other students) during a time period of stressful school exams and weather that was less amenable to outdoor activity.

Overall, correlational studies suggest reliable relationships between nature affiliation and eudaimonic aspects of well-being; however, vitality may be a specific aspect of emotional well-being that also correlates with nature affiliation. As we explore further on, another aspect of emotional well-being, awe, also appears to correlate with nature affiliation.

The experimental approach to studying associations between nature affiliation and well-being involves manipulating exposure to nature (e.g., via nature video clips or slides, plant-filled rooms, visualization involving nature settings, virtual experiences of nature, and, of course, actual experiences in real nature settings) and examining the resulting impact on indices of well-being. In addition to examining direct effects on well-being, mediator variables are also often examined and identified. A mediator variable helps to clarify the relationship between a manipulated or predictor variable and an outcome variable. For example, in study 3 by Nisbet et al. (2011) described above, environmental courses (predictor variable) led to an increased sense of nature relatedness (mediator), which resulted in higher levels of vitality (outcome variable). Therefore, increased nature relatedness mediated the relationship between environmental education and higher levels of vitality.

In recent years, several experimental studies have explored nature’s effect on people’s well-being. Mayer et al. (2009) conducted three experiments in which they manipulated participants’ immersion in nature and then had the participants complete scales of positive and negative affect along with the state version of the Connectedness to Nature Scale. In study 1, psychology undergraduate students were randomly assigned to spend 15 min in either a nature preserve or in an urban setting. In study 2, undergraduate psychology students were randomly assigned to spend 10 min in a nature setting or to watch a 10-min video clip of either the same setting experienced by those in the first group or a 10-min video clip of an urban setting. In study 3, undergraduate psychology students were randomly assigned to either a nature walk or to watch a video clip of the same walk. In all three of these studies, the nature condition had no effect on negative affect, but participants’ positive affect was boosted compared to those in the control conditions. Moreover, in all three of these studies, state nature affiliation was shown to mediate the effect of nature immersion on well-being: immersion in nature influenced positive affect via its effects on state nature affiliation.

Berman et al. (2008) randomly assigned undergraduate students to spend 50 min walking in either a park or a downtown, urban setting, before and after which they completed (among other measures) a self-report of positive affect. Mood was shown to increase for participants in the nature-walk condition but not for those in the urban-walk condition. This boosting of positive affect following immersion in nature held true in an experiment conducted by Valtchanov et al. (2010), in which undergraduate psychology students were randomly assigned to either a virtual experience of nature or to a virtual experience of abstract paintings immediately after a stress-induction experience. (The virtual experience of nature was an interactive computer-generated forest, of which its 1,600 m² could be explored using a head-mounted display and a wireless mouse. The experience was enhanced with somatosensory stimulation via a rumble platform which shook with each “step” a participant took and olfactory stimulation via a forest-scented air freshener.) Positive affect and skin conductance (among other measures) were assessed prior to and following the experience. Results showed that the computer-generated nature immersion significantly reduced participants’ skin conductance and elevated their positive affect relative to participants in the control condition. Similar findings emerged in a replication of this research by Valtchanov and Ellard (2010).

Participants’ levels of a variety of positive emotions were boosted in Saraglou et al. (2008) experiment that involved exposing psychology undergraduate students to film clips of varying subject matter and emotional content. Students who had viewed nature-oriented clips (e.g., childbirth, panoramic views of natural landscapes) reported higher levels of ecstasy, respect, and wonder compared to students who had viewed clips that were humorous or neutral in content. In a quasi-experiment conducted by Han (2009), Taiwanese children whose classroom was beautified with several plants were compared to a second group of children whose classroom had not been modified with the addition of plants. Although no difference between these two groups of children emerged on a specific measure of well-being, after two and a half months, the children in the “plant” classroom reported greater feelings of preference, comfort, and friendliness in relation to their classroom setting.

It has been shown that exposure to nature can also increase one’s endorsement of intrinsic goals such as closeness and community (which are associated with greater well-being), decrease one’s endorsement of extrinsic goals such as fame and fortune (the pursuit of which are associated with lower well-being), and cause an increase in generous behavior toward others. Weinstein et al. (2009) evidenced these beneficial effects in a series of four experiments. In studies 1 and 2, adults were randomly assigned to look at a series of four slides (for 2 min each) depicting either nature scenes or manufactured environments while following instructions to encourage immersion in the materials. A measure of intrinsic versus extrinsic aspirations was completed both before viewing the slides and after. In study 3, adult participants randomly assigned to view either nature or non-nature slides completed self-report measures of intrinsic and extrinsic aspirations, then engaged in a behavioral decision task in which their distribution of funds could be coded as reflecting an intrinsic aspiration (valuing another person) or an extrinsic aspiration (valuing money). In study 4, students were exposed to a 5-min period of relaxation in either a plant-laden or plant-free laboratory prior to completing self-report and behavioral measures of intrinsic and extrinsic aspirations. In all four studies, participants in the nature conditions endorsed more intrinsic and less extrinsic values, and these well-being effects on goal aspirations were mediated by state Connectedness to Nature scores. In study 1, results showed that degree of immersion in the materials interacted with the conditions in predicting change in aspirations, such that those who were exposed to nature slides and who experienced high immersion in the materials reported higher intrinsic aspirations and lower extrinsic aspirations than those in the non-nature conditions. In both studies 3 and 4, individuals immersed in nature behaved more generously toward others relative to individuals not immersed in the nature conditions. Indeed, Thomas Fuller’s assertion in 1732 that “he that plants trees loves others beside himself” (p. 89) appears to hold true even today and even with less active involvement in nature.

In conjunction with their correlational research (described previously in this chapter), Ryan et al. (2010) conducted a series of three experiments examining the impact of experiences in nature on subjective vitality. In study 1, undergraduate students imagined themselves in situations depicted in a subset of 8 of 64 total vignettes that varied randomly along three independent dimensions: physical activity versus no physical activity, social activity versus solitary activity, and indoor activity versus outdoor activity. For each vignette, participants rated the extent to which vitality was experienced. Results showed that vitality was impacted by all three of the dimensions varied in the vignettes—higher vitality was felt in relation to vignettes involving physical activity, the outdoors, and the presence of others. Importantly, these findings suggest that outdoor activity singly is related to vitality. In study 2, undergraduate students were randomly assigned to walk for 15 min either indoors or outdoors. Measures of vitality taken before and immediately after the walk revealed that vitality increased following the outdoors walk but not following the indoors walk. And in study 3, undergraduate students completed the measure of vitality before and after imagining themselves in either an outdoor natural setting or an outdoor manufactured environment. Results showed that vitality increased for those students exposed to imagined natural scenes but decreased for those exposed to imagined scenes of manufactured settings.

As demonstrated by these experimental research findings, nature affiliation and exposure to elements of the natural world affects our well-being in several ways: by boosting our positive affect; by eliciting feelings of ecstasy, respect, and wonder; by fostering feelings of comfort and friendliness; by heightening our intrinsic aspirations and generosity; and by increasing our vitality. An overall pattern is evident in both the correlational and experimental research: exposure to nature is, quite simply, good for us.

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