William James first posited the concept of voluntary attention in 1892 (James, 1892). James suggested this type of attention was consciously engaged when something did not intrinsically attract attention yet was important to address, and one in which effort was expended to perform. For James, voluntary attention not only meant focused concentration but also the suppression of potential distractions. Fredrick Law Olmsted, a contemporary of James and considered the father of landscape architecture in the United States, believed that the effort used to sustain voluntary attention might be subject to fatigue and incorporated nature into his urban designs as a remedy for recovery (Kaplan, 1995). Clinical neurologists, recognizing a similar process based on work with patients who had suffered brain damage, have defined the process as directed attention, a term later adopted by Kaplan to avoid confusion with James’s terminology (Kaplan, 1995).
Expanding on the observations of James and others, Kaplan and Kaplan (1989) introduced the attention restoration theory. The theory suggested that directed attention is subject to fatigue but can recover by removing attention-demanding activities and resituating oneself within an environment that required only involuntary attention. Involuntary attention is that which requires no effort because that which draws attention does so innately. Again, to avoid confusion with James’s terminology, Kaplan (1995) substituted the term fascination for involuntary attention and distinguished two types of fascinations along a hard–soft continuum. A hard fascination is one that draws attention in a dramatic fashion, such as a sudden loud noise or one consistent with imminent danger. A soft fascination is one that draws attention in an undramatic way, such as those experienced while among nature or natural environments. Kaplan (1995) suggested that it is these soft fascinations that provide the best environment for reflection and can most effectively enhance recovery from directed-attention fatigue.
Although fascination is the central element to directed-attention fatigue recovery, Kaplan (1995) described three others: being away, extent, and compatibility. Being away involves removing oneself from habitual activities that require directed attention. The shift can involve a physical escape to a new environment or a conceptual escape as one’s gaze or focus looks at a familiar environment in a new way. Extent means that the scope of a restorative environment must present an entirely different perspective and one that is expansive enough to engage as many faculties of thought as possible. Compatibility means that the environment must be consistent with the goals and purposes of the individual. The setting must accommodate the desired outcome, allowing the individual to think and behave naturally without cognitive effort or struggle (Kaplan, 1995).
Kaplan (1995) cited four studies that were particularly notable to the development of the theory. Hartig et al. (1991) compared the pretest and posttest results of a proofreading exercise (which requires a high degree of directed attention) among individuals who had taken a wilderness vacation (backpacking), a nonwilderness vacation (car tours, visiting friends, sightseeing tours), and those who took no vacation and continued to perform everyday activities. The wilderness group showed significant improvement in performance, whereas the nonwilderness and the control groups’ performances declined. In a second study, Hartig et al. (1991) reported similar results between participants who had been randomly assigned to take a walk in a nature setting or in an urban setting or who sat quietly and read for 40 min, each after being subjected to attention-demanding tasks to induce cognitive fatigue. Not only did members of the nature-walk group perform significantly better on proofreading performance, but they also self-reported a higher degree of perceived restorativeness than did the other two groups.
Cimprich (1993) observed that patients recovering from breast cancer exhibited a high degree of directed-attention fatigue. The experimental group participated in 20-min restorative therapies at least four times per week. The control group participated in no restorative therapy. The experimental group showed significant improvement in performance over the course of the study, whereas the control group’s performance declined over the study period.
Lastly, Tennessen and Cimprich (1995) studied how different views from college dormitory windows might influence the attention-restorative process among students. Four categories of views were identified, ranging from all natural to all built. In addition to performing better on a battery of attentional measures, students with a greater natural view from their windows rated themselves better able to perform directed-attention activities than those with built views.
In other studies involving college students, subjects were asked to assess their perceived restorativeness of different environments. Students rated natural settings, scenes of natural settings and urban settings with green space higher in perceived restorativeness when compared with urban settings, built environments, urban settings with no green space, and sports and entertainment settings (Hartig et al., 1997; Herzog et al., 1997; Laumann et al., 2001; Purcell et al., 2001). Felsten (2009) used four categories of scenes to evaluate college students’ perceived restorativeness of indoor campus settings used for the purpose of a study break. Actual campus settings were reimaged on a computer screen depicting four categories as background views, as well as classrooms and work areas. The campus scene with no view of nature was ranked the least restorative, whereas the window views of nature, views of land murals, and views of murals with water were measured as the most restorative, respectively.
Two experiments by Berman et al. (2008) evaluated the cognitive benefits of interacting with nature. Results from both experiments found that those who participated in a nature walk or viewed scenes of nature showed a significant improvement in cognitive abilities compared with those who walked in or viewed scenes of urban environments. Additionally, only the nature groups showed significant improvement in their attention levels. Using a similar protocol, Shin et al. (2011) found that subjects who walked in the forest showed significant improvement in cognitive function tests, whereas those who walked in a downtown urban environment did not. Additionally, participants who had walked in the forest exhibited a positive change in mood, whereas those who had walked downtown experienced a negative change.
Using three simulated conditions—a nature walk, a controlled condition, and a perturbation/distress condition—Crossan and Salmoni (2021) also evaluated the cognitive benefits of interacting with nature. Results indicated that only the walk in the simulated natural environment restored directed attention and improved cognitive function. Moreno et al. (2018) reported similar results using nature videos as part of a K–2 school curriculum. Students viewing nature videos significantly improved their academic scores compared with students who did not view the videos.
Research on nature’s effect on cognitive function typically incorporates a period of time in which the subject is exposed to a restorative environment to induce recovery from directed-attention fatigue or in which the participants had been exposed to restorative environments for certain periods of time. However, several studies support a coterminous effect of nature on cognitive function. In a study using six landscape conditions with varying degrees of greenness, Jiang et al. (2021) investigated the effects of these landscapes on drivers’ mental status and response times while concurrently driving at high speeds. The greener landscapes not only improved cognitive function, but as the landscape’s degree of greenness increased, mental status and response times improved, respectively. Adamson and Thatcher (2018) reported that the presence of plants or pictures of plants in offices improved participants’ completion time and reduced errors on reading and card-sorting tasks. Kaplan (1993) also suggested that the opportunity to redirect one’s focus and experience nature, even for brief moments, can help recovery from directed-attention fatigue.
The purpose of this study was to investigate whether the mental processes of memory and reasoning were enhanced when exercised concurrently in a natural environment and in the presence of soft fascinations (Kaplan, 1995) vs. an artificial environment such as an indoor classroom or lecture hall.
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