1 Introduction
Nature experiences promote human health (e.g., Hartig et al., 2014). On an individual level, people reported and showed physiological as well as psychological benefits when they stayed in nature surroundings (for reviews, see Berman et al., 2008; Bratman et al., 2019; Hartig et al., 2014; M. Kuo, 2015; for a meta-analysis, see Menardo et al., 2019). For example, Ryan et al. (2010) showed in a multimethod approach (using vignettes, physical outdoor experiences and diary writing) that nature experiences increased participants’ subjective vitality. In a qualitative study, Shrestha and colleagues (2021) showed that students reported being more energetic and self-aware when they walked through a natural rather than urban university campus setting. On a higher level of abstraction, societies as a whole also seem to benefit when citizens spend time in natural environments. For example, previous studies suggest that the amount of green space was associated with lower spending for medical care (Becker et al., 2019) and lower rates of aggression (F. E. Kuo & Sullivan, 2001). The benefits of nature for human well-being are thus uncontested.
With its possibility to design and experimentally control immersive nature exposure, Virtual Reality (VR) research can be helpful to underscore the conditions under which real and virtual natural environments increase human well-being (for a direct comparison between virtual and physical natural environment, see Reese et al., 2022; Browning et al., 2020). We are unaware of previous research testing whether human-made structures in nature affect the beneficial outcomes of nature. This question has practical implications because evidently, for most people, pristine nature is out of reach, with only less than three percent of earth’s terrestrial surface providing untouched environments (Plumptre et al., 2021). Yet, even natural environments with human-made structures may be inaccessible for many. We deem it imperative to understand the effectiveness of virtual nature experiences on well-being, as these virtual experiences allow controlled experimental variation of potentially benefitting (or hampering) conditions. In the current study, whether a short VR nature intervention increased peoples’ well-being, and whether human-made structures in the landscape make a difference for well-being.
Nature experiences and well-being
The World Health Organization (WHO) defines health as a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity (as is delineated in the first principle of the Preamble to the WHO Constitution; Grad, 2002). Thus, well-being that we focus on in this work is an important part of health. It is characterized by affective and cognitive components (Bratman et al., 2019). Theories addressing the benefits of nature for well-being often focus on subjective restoration (Menardo et al., 2019), stress reduction (Ulrich et al., 1991; Kondo et al., 2018a), affect changes (McMahan and Estes, 2015), and improvement of cognitive functioning (i.e., in terms of attention and memory capacity; Kaplan, 1995; Stevenson et al., 2018). In the current experiment, we follow these theories and assess restoration and subjective vitality as indicators of well-being.
According to two major theories in the field, the mental benefits resulting from nature experiences can be explained with both cognitive and affective explanations. Attention restoration theory (ART; Kaplan, 1995) focuses on cognitive dimensions, and claims that voluntary attention (i.e., attention directed to specific events, tasks, surroundings) depletes in urban environments or by conducting cognitively demanding (everyday) tasks. Once depleted, these attentional resources could be restored in natural environments. According to Kaplan (1995), this restoration derives from feelings of fascination, being-away, coherence, and compatibility that are inherent to natural surroundings.
The other influential theory—stress reduction theory (SRT, Ulrich et al., 1991)—argues that natural environments influence affective states and therefore facilitate recovering from stressors: Nature comprises of elements and structures that increase positive affect, which in turn improves well-being. Both theories—ART and SRT—received supporting research, both in real-life settings as well as in virtual nature settings (through VR, videos, or pictures; e.g., Brown et al., 2013; Gladwell et al., 2012; Valtchanov & Ellard, 2010; for meta-analyses on various aspects of restoration, see Menardo et al., 2019; Ohly et al., 2016; Stevenson et al., 2018; but see Johnson et al., 2021, for mixed evidence regarding cognitive performance). The beneficial effects of virtual nature are fascinating, as these virtual nature experiences—unlike physical nature experiences—usually lack natural odors, a more beneficial air composition, and a natural terrain underfoot (Alvarsson et al., 2010; Franco et al., 2017; Kuo, 2015). Thus, the visual input seems sufficient to evoke restoration effects, and thereby associations with nature seem particularly important (see Menzel & Reese, 2021, 2022; Egner et al., 2020).
Virtual nature and well-being
There is ample evidence that immersive VR nature experiences can reduce pain, stress, negative affect, heart rate, and blood pressure while at the same time, they can increase restoration, vitality, and positive affect (Anderson et al., 2017; Tanja-Dijkstra et al., 2018; Yu, Lee, & Luo, 2018; see; Browning et al., 2019; Hedblom et al., 2019; Mattila et al., 2020; Brivio et al., 2021; Reese et al., 2021, 2022; Frost et al., 2022). A study by Scates et al. (2020) even suggests beneficial effects on patients’ well-being in the context of cancer treatment, as a VR nature experience can distract patients, reduce their frustration, increase relaxation, and induce a feeling of peace.
Comparing the effectiveness of VR nature experiences with physical nature experiences, a meta-analysis on six studies (Browning et al., 2020) found that positive affect increased more strongly after a physical compared to a virtual nature experience; for negative affect, there was no significant difference observed. However, all reviewed studies were limited to people watching videos or pictures, rather than guiding them through an environment. Recent work directly comparing a VR and a physical nature walk provided evidence that VR nature experiences can have similarly strong effects on well-being outcomes than physical nature experiences: For example, Reese and colleagues (2022) experimentally varied whether participants conducted a physical nature walk or a VR nature walk. The VR nature walk was constructed to match the physical environment as closely as possible. Results suggested that the VR experience was similarly effective in improving well-being compared to the physical nature experience (Reese et al., 2022). However, corroborating the meta-analysis by Browning and colleagues (2020), several effects in the study by Reese et al. (2022) were slightly (yet non-significantly) stronger in the physical condition. In another study, Mattila and colleagues (2020) asked participants to explore a VR environment for five minutes. Following this brief intervention, participants reported better well-being (indicated through stronger restoration and vitality) as well as more positive affect than before. The authors could compare their results with data from another study assessing responses after visiting a physical forest (Hauru et al., 2012), suggesting that the VR environment was seen as equally restorative as a comparable physical forest, yet even more fascinating and coherent. It is likely that the high degree of realism that highly powered virtual environments allow contributes to the effectiveness of such interventions (Newman et al., 2022). Taken together, findings suggest that VR nature experiences can evoke well-being benefits that resemble those of real nature.
Effects of human-made structures in nature on well-being
The goal of this experiment was to test whether a short VR nature intervention increased peoples’ well-being, and whether human-made structures in the landscape make a difference for well-being. Previous work highlights that the dichotomy of “nature” vs. “city” applied in many studies assessing the well-being benefits of nature may not always be useful (Staats et al., 2016; Weber & Trojan, 2018). Most natural spaces in densely populated countries, in particular in urban areas, are characterized by human structures. In fact, many studies on restoring effects of nature were conducted in urban green spaces such as parks (Kondo et al., 2018b; Mygind et al., 2021; Mygind et al., 2019). In how far human-made structures influence nature-based health benefits remains to be answered, and the current study seeks to provide first empirical evidence. We expected that a natural environment without human-made structures would increase well-being more than the environment with human-made structures because built elements are typically associated with negativity (such as stress, noise, crowding; Egner et al., 2020; Menzel & Reese, 2021). Also, built elements alter visual properties of a scene and therefore influence processing fluency, which is discussed to be related to restorativeness (Joye & van den Berg, 2011) and discomfort in urban environments (Wilkins et al., 2018). Furthermore, previous studies suggest that managed nature seems to be less preferred than wild nature (Van den Berg and Koole, 2006). Moreover, human-made structures may reduce feelings of coherence, fascination, or being carried away (cf. Kaplan, 1995), because they (primarily) serve humans by providing shelter (e.g., walls, huts) or enable to trespass natural structures (e.g., bridges, paths).
However, one could argue that human-made structures do not hamper the beneficial effects of nature. For example, people may perceive human structures in nature as compatible with their goals (e.g., hiking over paths or seeking shelter for lunch). As Kaplan (1995) argued, “the setting must fit what one is trying to do and what one would like to do” (p. 173). Also, people in highly industrialized countries (who are often representing the samples of previous studies) are hardly confronted with untouched nature so that managed nature with human-made structures could represent the “preferred places” for everyday restoration (Korpela et al., 2008). Taken together, while there is evidence for both hampering and benefitting effects of human-made structures in nature, we deem the evidence for hampering effects as more convincing. The current research may thus contribute to recent theoretical advances in understanding how various levels of nature characteristics affect the quality of well-being. It may also represent a starting point for understanding the conditions in VR that are particularly effective, complementing work on the types and extent of physical nature relevant for human well-being (Ekkel & de Vries, 2017). Specifically, the current experiment set out to provide a first test on whether human influence within nature affects well-being.
The present research
We conducted a VR-experiment with two different virtual nature settings: wild nature and nature with human-made structures. Based on the arguments developed above, we tested the following two hypotheses:
(1) In both the “wild nature” and “nature with human-made structures” VR environments, participants report higher subjective vitality after compared to before the intervention.
(2) The effect in (1) is more pronounced in the “wild nature” condition.
(3) Participants in the “wild nature” condition report higher levels of restoration than those in the “nature with human-made structures” condition.
We used subjective vitality and restoration as indicators of well-being. Subjective vitality (Ryan & Frederick, 1997) is seen as an eudaimonic construct that refers to experiences and feelings of having energy and vigor, and thereby reflecting intrinsic well-being (Shreshta et al., 2021). Vitality enables individuals to actively seek purposive actions, and it covaries with physical conditions (such as brain activation; see Barrett et al., 2004), so that it can be seen as a valid measure of well-being (Ryan and Frederick, 1997). Restoration was used, because it has been proved to be highly suitable for measuring perceived change in psychophysiological and mental restoration (Han, 2018). Both measures were successfully implemented in previous VR studies (e.g., Mattila et al., 2020; Reese et al., 2021, 2022; for a review, see Browning et al., 2020). For exploratory reasons, we assessed motion sickness among participants. We expect no differences in motion sickness across conditions, but previous studies suggested that motion sickness can reduce well-being effects of virtual nature experiences (e.g., Reese et al., 2022).
4 Discussion
The reported study supports previous research showing that VR nature experiences can increase well-being. The increase in subjective vitality as well as evoked restoration were similar for both VR environments that primarily differed in the visibility of human-made structure. Thus, regardless of whether participants saw human influence within nature or not, the virtual reality nature experience had a positive effect on participants’ well-being, corroborating to Hypothesis 1. The relatively high levels of restoration that were significantly above the scale mean and comparable in size to previous studies using VR and comparing it to real nature (e.g., Mattila et al., 2020; Reese et al., 2021, 2022) emphasize the restorative value VR nature exposure can provide. However, rejecting Hypotheses 2 and 3, there was no difference between the conditions with regard to subjective vitality and restoration. Thus, overall, this study suggests that VR nature experiences may be an appropriate path to increase well-being—regardless of human-made structures—for people who cannot visit real nature for whatever reason, resonating with previous studies (Chirico & Gaggioli, 2019; Mattila et al., 2020; Reese et al., 2022).
The current experiment suggests that it does not really make a difference, at least in the current setting, whether natural VR environments include human-made structures or not. As we argued above, it is likely that people see human-made structures as compatible with their (restoration) goals. Furthermore, they may be signals of safety for people mainly growing up in urban settings. In a post-hoc analysis comparing participants grown up in rural settings with those in more urban settings, however, we did not find any clue that this plays a role. Possibly, because growing up rurally in Germany also means being constantly surrounded by human-made structures. Anyhow, as intended, the human-modified condition still represented a natural environment, and therefore, associations evoked by natural environments (likely shaped by previous experiences in such environments) may be similar for both conditions—regardless of interspersed human-made structures. As such, for landscape planners this result is useful as it suggests that human-made elements within urban park or forest surroundings may not be detrimental to the goal of restoration.
As we did not find a significant difference between both conditions, our results suggest that other factors, such as visual appeal of the natural environment or specific needs for restoration, (additionally) affect how people respond to nature with human-made structures (Twedt et al., 2019; see also Allard-Poesi et al., 2022). Future studies should systematically vary quality and quantity of human-made structures in natural environments to study under which conditions human structures may hinder (or even facilitate) well-being, and thereby provide valuable information for urban and landscape planners.
A limitation of the current study refers to the comparability of the two landscapes used. Although we believe that both virtual environments were very similar in terms of visual appearance, content, and number of natural elements, it is possible that one might have led to more intense feelings of being away or other relevant differences. For example, the colors in the nature setting with human-made structures were somewhat more muted than the saturated green colors of the wild environment. In fact, it would have been informative to assess the perceived restorativeness (Hartig et al., 1997) of both environments to gain insights into potential processes underlying the benefitial well-being effect (e.g., evoked feelings of being away). In addition, future research could address in how far different natural environments and depictions in VR or in augmented reality motivate people to act in favor of such places (e.g., Blythe et al., 2021; Dunn et al., 2021; Silk et al., 2021). For example, while our study provides a first step towards understanding potential differences between more pristine versus more man-made natural settings, we suggest that future research systematically varies the extent and amount of man-made structures. Natural scenes share characteristics, including measures of fractality, that are likely altered by human-made structures (e.g., Braun et al., 2013; Menzel & Reese, 2021). Although it is suggested that differences in such characteristics are associated with restorativeness (Joye & van den Berg, 2011), evidence is scarce (Menzel & Reese, 2021, 2022). To address such gaps in the literature, researchers could use custom-built virtual surroundings (as in Mattila et al., 2020, or Reese et al., 2022) rather than existing and only proximating environments, and distribute low, medium or high numbers of human-made structures within the visible natural environment. A more rigorous setting would also allow to compare these with a control group (e.g., an urban setting or indoor environment) without any indication of nature. In fact, this may allow developing a continuum perspective that more explicitly delineates the mechanisms that link (urban) nature to well-being (cf. Marselle et al., 2021, for a discussion about the role of different levels of biodiversity for well-being; see also Ekkel & de Vries, 2017).
Another limitation of the current experiment is the relatively homogeneous sample of young, educated participants. It is likely that these “digital natives” are more prone and used to computer-mediated interventions so that future research on the effects of virtual nature exposure on well-being should implement more diverse samples. However, other studies in the field with more age-diverse samples come to very similar conclusions regarding the effectiveness of VR nature interventions (see for example Tanja-Dijkstra et al., 2018, Study 2). Also related to the sample, statistical power is often a problem in VR studies (for a brief overview on samples sizes, see Browning et al., 2020; Reese et al., 2022). In the current study, the achieved statistical power (post-hoc) of the subjective vitality effect from t1 to t2 was 1-β > 0.95; for the between-subjects effect on restoration, it was 1-β = 0.09. As a consequence, between-subjects effects, in VR studies, should be treated with caution and further investigated in future studies. However, we would like to note that VR research as well as other resource intensive research setups often require a balance between samples size and feasibility.
Finally, we suggest that future research more closely inspects the role of motion sickness (e.g., Dziuda, Biernacki, Baran, & Truszszynski, 2014; Kim, Park, Choi & Choe, 2018) with regard to restoration effects, although in our current study no negative influence was found (but caution is needed due to the exploratory character of our analysis). A recent study by Reese and colleagues (2022), however, suggests that a lack of motion sickness may amplify restoration effects (as do the descriptive statistics in the current study). Therefore, it would be helpful when motion sickness can be reduced in future applications.
Taken together, the current experiment set out to test whether human-made structures within nature environments can hamper well-being outcomes. Apparently, they do not, and thus experiences in nature—both in physical and virtual—can be means to help people increase their well-being, regardless of subtle human influence.