Tracking restoration in natural and urban field settings

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Abstract

We compared psychophysiological stress recovery and directed attention restoration in natural and urban field settings using repeated measures of ambulatory blood pressure, emotion, and attention collected from 112 randomly assigned young adults. To vary restoration needs, we had half of the subjects begin the environmental treatment directly after driving to the field site. The other half completed attentionally demanding tasks just before the treatment. After the drive or the tasks, sitting in a room with tree views promoted more rapid decline in diastolic blood pressure than sitting in a viewless room. Subsequently walking in a nature reserve initially fostered blood pressure change that indicated greater stress reduction than afforded by walking in the urban surroundings. Performance on an attentional test improved slightly from the pretest to the midpoint of the walk in the nature reserve, while it declined in the urban setting. This opened a performance gap that persisted after the walk. Positive affect increased and anger decreased in the nature reserve by the end of the walk; the opposite pattern emerged in the urban environment. The task manipulation affected emotional self-reports. We discuss implications of the results for theories about restorative environments and environmental health promotion measures.

Introduction

Work pressures, urban noise, and other stressors drive many people to seek relief through outdoor recreation (Knopf, 1983; Schreyer, 1989). People are frequently drawn to recreation settings such as wilderness areas and urban parks by opportunities for viewing scenery, contact with nature, and solitude (Knopf, 1987; Hartig, 1993). Such opportunities have been provided by planning and legislation grounded in widely held beliefs that natural surroundings aid the physical and psychological restoration of people living in cities (e.g. Olmsted, 1870).

Although influential, the hypothesis of enhanced restoration in natural environments has only rarely faced experimental tests. In particular, few experiments have compared restoration in natural and urban environments following the controlled imposition of psychological demands that induced a potential for restoration to occur. These experiments have documented a restorative advantage of natural environments in the ability to focus attention (Hartig, Mang, & Evans, 1991, Study 2) and in emotional states (e.g. Ulrich, 1979; Hartig, Böök, Garvill, Olsson, & Gärling, 1996). Evidence of enhanced psychophysiological recovery comes from a laboratory experiment in which autonomic arousal was monitored during 10-min videotapes of natural vs urban environments (Ulrich et al., 1991; see also Parsons, Tassinary, Ulrich, Hebl, & Grossman-Alexander, 1998; Laumann, Gärling, & Stormark, 2003).

Why might natural environments better serve physiological, emotional, and attentional restoration than urban surroundings? The experiments cited above started from one or both of two theories. Although the two theories have some common features (Hartig & Evans, 1993), they deal with different antecedents and emphasize different restoration outcomes. Attention restoration theory (ART; Kaplan & Kaplan, 1989; Kaplan, 1995) complements analyses of overload in urban environments (Milgram, 1970; Cohen, 1978) by proposing factors that work in the renewal of a depleted capacity for directing attention. According to ART, restoration from directed attention fatigue occurs with psychological distance from routine mental contents (being away) in conjunction with effortless, interest-driven attention (fascination), sustained in coherently ordered environments of substantial scope (extent) when the person's inclinations match the demands imposed by the environment as well as the environmental supports for intended activities (compatibility). Kaplan and Kaplan (1989) argue that these four factors commonly hold at high levels in natural environments.

An alternative theory about restorative environments emphasizes the physiological and emotional changes that can occur while viewing a scene after a situation involving challenge or threat. Ulrich (1983) proposes that perceiving particular qualities and contents in a scene can support psychophysiological stress recovery. Moderate depth, moderate complexity, the presence of a focal point, gross structural qualities, and natural contents such as vegetation and water can evoke positive emotions, sustain non-vigilant attention, restrict negative thoughts, and so aid a return of autonomic arousal to more moderate levels (cf. Fredrickson & Levenson, 1998; Shapiro, Jamner, Goldstein, & Delfino, 2001). Ulrich views humans as biologically prepared to respond positively to environmental features that signal possibilities for survival, and so assumes an evolutionary basis for aesthetic and restorative responses to some natural scenes.

These theories appear to complement one another with regard to the antecedent condition from which the person becomes restored. The elevated physiological arousal and negative affect characteristic of stress can occur in the absence of directed attention fatigue. Conversely, elevated arousal or negative affect need not always accompany attentional fatigue (Kaplan, 1995). Yet some researchers have discussed attentional fatigue as an aftereffect of stress (Cohen, 1978; cf. Ulrich et al., 1991), and others have treated it as a condition that increases susceptibility to stress (Kaplan, 1995; cf. Lepore & Evans, 1996). Thus, each of the antecedent conditions may occur alone in some circumstances, but in other circumstances they may have some form of reciprocal relationship or otherwise coincide. Just which character the antecedent condition has determines the dimensions along which restoration can proceed.

The relative timing of environmental effects along the given dimensions may have a bearing on whether the two theories address complementary processes. Differential effects of natural and urban environments can appear quickly in physiology (within 4 min in Ulrich et al., 1991; cf. Fredrickson & Levenson, 1998) and emotional states (within 10–15 min; e.g. Ulrich, 1979). In contrast, environmental effects on performance have not consistently emerged after 15–20 min (cf. Hartig et al., 1996; Laumann et al., 2003), but they have appeared after longer periods. Over an extended period, some of the initial effects may dissipate. Hartig et al. (1991, Study 2) did not find significant differences in blood pressure or heart rate measured after a 40-min walk in a natural or an urban field setting (cf. Ulrich et al., 1991), but they did find environmental effects on emotional states and proofreading performance. Recognizing that environmental effects on physiology might have emerged early in the walk and then dissipated as it came to an end, they noted a need for measuring physiological changes during the course of a walk. When applied to attentional performance and emotional measures as well, such a repeated measures strategy can provide insights on the relative timing of the different forms of restoration outcomes. That some effects appear after others have dissipated would suggest that more than one process may have operated in producing the set of outcomes.

In the experiment reported here we compared restoration in natural and urban field settings. To track restoration along different dimensions, we used multiple measurement methods in conjunction with a poststressor period that previous research suggested would suffice for the environments to differentially affect performance. With the use of ambulatory monitoring equipment we obtained repeated measures of systolic and diastolic blood pressure (SBP; DBP) from young adults in two successive recovery contexts: first while sitting in a room with or without views of trees and then while walking in a nature reserve or an area of medium-density urban development. We also assessed emotional states and performance before, during, and after the walk.

The outcomes measured at a given point in time have to do not only with the environment available for restoration but also with the severity of attentional fatigue and/or stress reactions the person experienced just before entering that environment. Thus, varying the antecedent condition should aid the examination of different forms of restoration and environmental influences upon them. Applying this reasoning, we included a task manipulation in the present experiment with a view to imposing intense attentional demands on half of the subjects for an extended period just before the environmental “treatment.”

In sum, we experimentally tested hypotheses about the relative restorative values of natural and urban settings for people who had faced different kinds of prior demands. In contrast to the subjects in the urban environment, we expected the subjects in the natural environment to show more rapid BP decline during the initial minutes of the treatment period (Hypothesis 1); lower BP during the walk (Hypothesis 2); more positive emotion during the walk (Hypothesis 3); more positive change in emotion following the walk (Hypothesis 4); and greater improvement (or a smaller decrement) in performance on an attentional task following the walk (Hypothesis 5). We also wanted to see whether environmental effects on performance would appear already during the walk, whether environmental effects on physiology would persist into the postwalk period, and how the varying levels of attentional demands imposed prior to treatment would become manifest in the pattern of outcomes subsequently observed.

Section snippets

Design

The experimental design crossed an environmental treatment condition (natural, urban) with a pretreatment task condition (task, no-task). The environmental treatment had a seated indoors phase and a walking outdoors phase. In the natural environment, the two phases were sitting in a room with tree views, then walking in a nature reserve. In the urban environment, the two phases were sitting in a room without views, then walking in an urban area. Note that with the seated-indoor phase we could

Physiological effects

While seated indoors during the first 10 min after the task or drive, those subjects who had views of trees showed only a marginally steeper decline in SBP than those who did not have a view (p<0.12) (see Fig. 4). Those subjects who had just completed the drive showed steeper SBP declines than those who had just completed the task (see Fig. 4, top panel); for the task×time interaction, F(2,180)=3.63, p=0.03.

In contrast to the marginal effect seen in SBP and in line with Hypothesis 1, the

Evidence of restorative effects of natural environments

First and foremost, our results speak to widely held beliefs that natural surroundings aid the physical and psychological restoration of people living in cities. To ensure a potential for restoration, we imposed different demands on our subjects—tasks requiring focused attention, performed for an hour after arriving at a field site, or the drive to the field site in and of itself. Following these demands, we found that our comparison settings had opposed effects in each of the three remaining

Acknowledgements

This study was supported by USDA Forest Service Cooperative Agreement 28-C8-469; an American Psychological Association Dissertation Research Award; and a Dissertation Fellowship from the School of Social Ecology, University of California, Irvine (T.H.). Manuscript preparation was partially supported by NHLBI Training Grant T32 HL07365-14 (T.H.). We thank Susan Berg, Joanne Berry, Christine Drass, Christine Fong, Anjolette Fruehan, Marcos Martinez, Dan Mathiesen, Michael Richmai, Glen Segrue,

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