Web site logical path: [www.psy.gla.ac.uk] [~steve] [myNewWave] [this page]

Green space effects

This page is to summarise and hold pointers about the "Green space" phenomenon. (I now also have a section below on "Blue space phenomena".) I feel we can call it a phenomenon because there are too many reports of carefully observed effects to leave much doubt that there is something substantial here; but no agreement on theory, nor on the scope of the field or area. I list a few student research projects here in this field. I then mention some published papers, selected to illustrate some of the various aspects of the area.

Some projects here on green space

• Paterson,L. (2015) An Investigation into the Impact of Outdoor Space and Exercise on the Attention of Primary School Children (Student project) PDF
  This study controlled for the amount of exercise.
• Correia,M. (2015) An investigation into the restorative effects of the outdoors on undergraduate students (Student project) PDF
  Marta showed in her project that undergraduates performed better after a break going to a park, than a break spent doing what they liked, or nothing.
• Jiang, Dianyi (2018) The influence of a natural environment on cognitive abilities and emotion (Student project) PDF
  This replicated and extended studies that showed the beneficial effects, not of being physically present in "green" environments, but of looking at pictures of them.
• Dix, Charlotte (2020) "Exposure to virtual environments: Potential antecedents to the Green Space Effect" (Student project) PDF
  This study tested whether watching a 15-minute video of an urban or a natural environment would increase cognitive capacity by attentional Restoration after a 10 min. fatiguing task. Additionally, the concept of Nature Relatedness as a trait was measured to explore if this construct could explain variation on score differences between trials. 28 members of the general public participated in an experimental online meeting. The main outcome measures used were: Digit Span Forwards, Digit Span Backwards, and Digit Span Sequence, taken in a pre-test and post-test format.
• Erdinc, Huner (2020) "Watching a nature video improves negative affect and stress but does not change positive affect" (Student project) PDF
  This study showed that a nature video of only 3 minutes and 42 seconds duration caused improvements in two measures of wellbeing: significant decreases in negative affect and in stress scores with effect sizes of -.69 and -.78 respectively.
• Lui, Wei (2021) "Is it the green in nature videos that affects mental well-being?" (Student project) PDF
  This project tested 4 different short videos: urban environment with fascinating stimulation, urban environment with distracting stimulation, green space environment with fascinating stimulation, and green space environment with distracting stimulation. It demonstrated that an urban environment may also have positive effects on negative moods as long as it provides fascinating stimulations instead of distracting ones. I.e. that "green" and "nature" are not necessary for these positive effects.

Some lit. refs on green space

• Kaplan, S. (1995) "The restorative benefits of nature: Toward an integrative framework" Journal of Environmental Psychology 15, 169-182.
• Kaplan, S. (2001). Meditation, restoration, and the management of mental fatigue. Environment and Behavior, 33, 480-506.
• Berman, M.G., Jonides, J., & Kaplan, S. (2008) "The Cognitive benefits of interacting with nature" Psychological Science vol.19 no.12 pp.1207-1212. doi: 10.1111/j.1467-9280.2008.02225.x
• Kaplan, S. and Berman, M.G. (2010) "Directed Attention as a Common Resource for Executive Functioning and Self-Regulation" Perspectives on Psychological Science 5(1) 43-57 doi: 10.1177/1745691609356784
• Wallner,P., Kundi,M., Arne Arnberger,A., Eder,R., Allex,B., Weitensfelder,L. and Hutter,H. (2018) "Reloading Pupils' Batteries: Impact of Green Spaces on Cognition and Wellbeing" Int. J. Environ. Res. Public Health vol.15 1205 doi: 10.3390/ijerph15061205 Applies ART to breaks for school children.

3. On the other hand, an interview in New Scientist with neuroscientist Daniel Levitin has him asserting that what stresses (fatigues) humans is not concentrating attention but switching contexts; and the remedy is day-dreaming not necessarily green space. (I however think that the restorative properties of green spaces often are to do with being able to let your mind drift while walking with nothing too taxing in the way of carrying out the walk. So that this perspective may be important.) [A different idea about the cause of green space effects.]

• Tiffany O'Callaghan (2014) "How daydreaming can help you beat information overload" (alternative title "It's all too much!") New Scientist issue 2982 | magazine cover date: 16 August 2014

4. Plant chemicals, and other ecological factors. [Yet wider ideas about the causes of green space effects.]

• Craig, Logan and Prescott (2016) "Natural environments, nature relatedness and the ecological theater: connecting satellites and sequencing to shinrin-yoku" Journal of Physiological Anthropology (2016) vol.35 no.1 doi:10.1186/s40101-016-0083-9

5. Physical exercise. [An alternative wider idea about the causes of green space effects.]
Opezzo et al (2014) [Opezzo14]] is a notable paper in this area. Firstly, it asks the question of whether the physical exercise usually involved in being in a green space is in fact the main cause of the benefit. Given the enormous amount of evidence for the benefit of exercise to not only physical health, but also mental health, it is important to research this. The study showed that both green space and exercise have a significant benefit, and that although exercise has a greater effect, green space has an additional, independent, one. That is: exercise is important, but not the sole explanation for the effect. From now on, we should scrutinise every study to see whether exercise has been ruled out as an explanation of the results.

The study used "divergent thinking" as its measure, which is a common test of creativity. [This paper thus also offers evidence of a second effect of green space, other than improved attention.]

Furthermore, the study measured the duration of the effect: the improvement in divergent thinking lasted only about two minutes. Most studies fail to measure how long their effect lasts, tacitly assuming that it is durable. It may be that this explains a puzzle in some of the studies of green space effects on school pupils' attention, where teachers were positive that the green space condition results in marked improvements in attention, yet the study failed to show any improvement in tests of learning. It could be that the effect lasts for less than a whole school period (plus time for a test as well).

• Opezzo, M. & Schwartz,F.L. (2014) "Give Your Ideas Some Legs: The Positive Effect of Walking on Creative Thinking" Journal of Experimental Psychology: Learning, Memory, and Cognition Vol.40 no.4 July 2014 pp.1142-1152 doi: 10.1037/a0036577

6. A general effect on well-being as well as on health and on cognitive performance. [This paper thus offers evidence of another, wider effect of green space.]

• Mathew P. White, Ian Alcock, James Grellier, Benedict W. Wheeler, Terry Hartig, Sara L. Warber, Angie Bone, Michael H. Depledge, Lora E. Fleming. (2019) "Spending at least 120 minutes week in nature is associated with good health and wellbeing" Scientific Reports vol.9 ArticleNmb: 7730 vol9:7730 Pub Date: 2019-06-13 doi:10.1038/s41598-019-44097-3 [This is a correlational study between min.s of green exposure in last 7 days with self-reported health and well-being. >=120 mins (2 hours) that week was the threshold. N = 19,806. Multi-national. The effect reached its maximum at about 240 mins (4 hours).]

7. Wider effects on children's upbringing. [This paper thus offers evidence of yet another, wider effect of green space.]

There are increasing claims about the benefits of lots of outdoors time for children over long periods (years).

• Kernan, M. & Devine, D. (2010) "Being confined within? Constructions of the good childhood and outdoor play in early childhood education and care settings in Ireland" Children & Society vol.24 no.5 pp.371-385. doi: 10.1111/j.1099-0860.2009.00249.x
• For more summaries and references along these lines, see material in Carol Craig's Centre for confidence and well-being, particularly   this web page on Young People
• Also see Dadvand15 and Schutte17.

Web documents, mostly with literature references

Particularly these articles:   1   2   Young People

Stimuli

What is it about "green space" that determines its effectiveness?

• Ulrich84 reports on patients who were indoors (in a hosptital bed) and definitely NOT "in" green space, but what they saw out of the window made a difference => so vision alone can be effective, physical immersion not essential.
• Does it have to be realistic? Probably not. High definition TV doesn't work: it's belief in its reality that matters. Hahn08.
• But your belief in its realism can matter. One condition in Snell19 only worked when the participants believed they were watching a live video (like CCTV), not when they believed it was recorded.
  • Snell,T.S., McLean,L.A., McAsey,F., Zhang,M. and Maggs,D. (2019) "Nature Streaming: Contrasting the Effectiveness of Perceived Live and Recorded Videos of Nature for Restoration" Environment and Behavior 2019 vol.51 nos.9-10 pp.1082-1105 doi:10.1177/0013916518787318

  And Kjellgren10 reports that a simulation of greenspace is not as effective as the real thing. But that may be because of reduction in belief of its realism, not because the sensory perception has to be hi-fi.

• Conversely, full immersion in the real green space is ineffective if you take a digital device with you [Jiang19], so paying attention is as important as where you are and "realism".
  Jiang19 did a 2X2 study on the the four cases of greenspace vs. indoors, and whether the person does/not have a digital device with them. Basically: having a device cancels the benefit of real green space – so the space is not enough, you have to be somehow attending to it.

• Many of the effects depend on what the exact measure is: there is nothing like a single type of "restoration": Snell19.

Being in nature vs. videos vs. still pictures

• Berman08 compared nature versus cities, and showed that ≈ 50 min.s of walking or 10 min.s of viewing pictures were both sufficient to show a "green space" effect.
• While videos have been used as stimuli in green space research since at least 1998, I haven't seen direct comparisons of
  • Being outdoors
  • Seeing it through a window
  • Videos
  • Viewing still pictures
  All of these have been shown to have (some) green space effects.

Measures

Trait measures of nature-relatedness

• The nature connectedness scale (NCS)
  Mayer, F. S., & Frantz, C. M. (2004). "The nature connectedness scale: A measure of individuals' feeling in community with nature". Journal of Environmental Psychology, 24, 503-515 doi: 10.1016/j.jenvp.2004.10.001
• The NRS (Nature Relatedness Scale): Nisbet11. Nesbet09.
  Nisbet E, Zelenski J and Murphy S (2009) "The Nature Relatedness Scale: Linking individuals' connection with nature to environmental concern and behavior" Environment and Behavior 41: 715-740. doi: 10.1177/0013916508318748
• The NCI: Nature Connectedness Index. A simple 6 item Likert scale, suitable for children as well as adults. Some validation in the study in Richardson19 doi: 10.3390/su11123250.

• Only Richardson19 made any attempt to get a sample that is representative of the population. That paper says they got "a representative sample of the English adult population (aged 16 and over)" but gives no details of the method for that. Since they seem to be self-selected, it is unclear how effective that is at achieving a representative sample. So while they look at first like a development of a trait dimension like the big five personality ones, they may well only apply to a minority of the population.
• The arguments in their papers (e.g. Richardson17) go from evidence of correlations between (a) health, wellbeing, and access to greenspace; (b) access to greenspace and nature connectedness (NC); (c) NC and heatlh; to the implication of a real relationship between NC and health without any attempt to control for wealth vs. poverty. Access to greenspace of course is greater for affluent people than for poor people; but the direct connection between health/wellbeing and wealth is stronger. They make no attempt to control for this, and seem unaware that this is important for their argument to have any merit.
• There seems to be no study of whether individuals' scores on these scales are stable over time, which we expect if NC were a "trait" rather than how they felt in a moment of enthusiasm when they filled it in. Richardson19 does show its cross-sectional pattern, which varies markedly with age; suggesting that it is not a stable trait-like characteristic.
• There is usually no definition of "nature". Generally, in our culture, it refers to all non-man-made things. But if you substitute "inhuman" for "nature" you would preserve that meaning but not the meaning they want you to have. There is no discussion of the issues here. For instance smallpox, polio and fleas are natural but I at least regard them as bad, and hope never to feel connected to them. Again, one large section of the population wants green space to walk their dogs in; but dogs are in major conflict with birds, especially ground nesting birds. When dogs come in, many species of non-human nature leaves in a hurry, and indeed farm animals are also repeatedly injured and killed.

It would not be hard to address such weaknesses should someone wish to do so, and discover whether there is a property something like nature-relatedness with stable meaning. It would be a kind of attitude.

However these "criticisms" may be beside the point. These scales appear to come from a different viewpoint and are used for a different purpose. Often they are used on visitors to green-related facilities, where the degree of public support is important: both political support for policies, but even more for funding support for such things as public gardens, or tree planting. Most such things do not need to appeal to a majority, they only need a particular subgroup to desire them. Getting an instrument for these purposes would be a different issue. As one report put it, this is about developing a "Monitor of engagement with the natural environment", and not about whether greenspace is a general effect on most people. Such instruments do not require majority usage.

Affect and Wellbeing

McMahan18 discusses several measures of affect.
In particular the frequently used PANAS (Positive and Negative Affective Schedule) which is a 20 item scale, with separate subscales for positive and negative: see Watson88 for details.

The short Warwick-Edinburgh Mental Well-Being Scale (SWEMWBS): StewartBrown09. The SWEMWBS is a 7-item version of the original 14-item Warwick-Edinburgh Mental Wellbeing Scale and measures a combination of eudaimonic and hedonic wellbeing. Each item is a statement about an individual's experiences over the past two weeks, responded to on a five point Likert scale. It contains only positively worded items, and a greater average score indicates greater mental wellbeing. It is brief, widely used, and has strong psychometric properties.

Subjective measure of restorativeness

Stress

• Stress-VAS – see Kjellgren10.
  This scale measures the individual's self-estimated level of current stress. It has a horizontal line with the anchors "not at all stressed" on the left- hand side, and "maximally stressed" on the right-hand side. The question asked was: "How stressed do you feel right now?"

• Anxiety. State Trait Inventory for Cognitive and Somatic Anxiety (STICSA).
  • Ree08.
    Ree. MJ, French D, MacLeod C, et al. (2008) Distinguishing cognitive and somatic dimensions of state and trait anxiety: Development and validation of the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA). Behavioural and Cognitive Psychotherapy 36: 313-332.

  • Gros07, Gros10.
    Gros DF, Antony MM, Simms LJ, et al. (2007) Psychometric properties of the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA): Comparison to the State-Trait Anxiety Inventory (STAI). Psychological Assessment 19: 369-381.

    Gros DF, Simms LJ and Antony MM (2010) Psychometric properties of the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA) in friendship dyads. Behavior Therapy 41: 277-284.

  • VanDam13. Van Dam NT, Gros DF, Earleywine M, et al. (2013) Establishing a trait anxiety threshold that signals likelihood of anxiety disorders. Anxiety Stress and Coping 26(1): 70-86.

Physiological measures

• GSR (galvanic skin response) = SC (skin conductivity) = SCL (Skin conductance level) = electrodermal activity.
• Heart rate = pulse rate.
• Heart rate recovery after stress i.e. the rate at which it returns to normal, or reduces after a stress.
• IBI (cardiac inter-beat interval) (see Kaumann03). This requires an ECG: electrical measurements of the heart through skin electrodes.
• EEG: electrical measurements of the brain through skin electrodes on the head.
• Changes in Blood Pressure.

Attention control i.e. ability to direct attention

• Digit span forward (DSF)
• Digit span backward (DSB),
• Digit Span Sequence (DSS);
• Necker Cube Pattern Control (NCPC).
• Sustained Attention to Response Test (SART). This is a reaction time and accuracy test.

Creativity

One test is for "Divergent thinking", using GAU (Guilford's Alternate Uses test).

"Convergent thinking" is a test of another aspect of creativity. The compound remote-association test (CRA) measures this.

"Barron's symbolic equivalence" task (BSE; Barron, 1963). The BSE depends on the generation of analogies.

Time scale / duration

Cross-sectional studies

It might be quite good in these times, since people were caught in lockdown and not able to choose their view of greenspace, and so this type of study would avoid the full force of self-selection which tends to confound cross-sectional research.

Active intervention on two occasions: e.g. over a week

One occasion: immediate effect within 30 - 60 mins

Some time durations of interventions: for the length of green space exposure in various studies

• 3:40 min. video, with soundtrack. Curently under test. This video is a composite comprised of materials from the open access site https://www.pexels.com/search/videos/nature/
• 4 mins. Opezzo14: 4 min. interventions. It is notable that here, the interventions were not done before the tests; but that their Ps filled in the tests while walking/etc. So "the intervention time" taken was throughout the tests, but none in advance.
• 10 mins. Berman08 (expt2) 10 mins viewing pictures and rating them.
• 15 min. CDix20.
• 25 min. Aspinall13
• 30 mins per week Shanahan16. Shows sig. health effects. e.g. blood pressure, depression.
• 30 min.s Paterson15. Primary school breaks: 30 mins actually IN the greensp. 15+15 min walking there and back. Tests done in the school pre and post.
• 50-55 mins. Berman08 A whole walk (2.8 miles). (expt1)
• 2 hours per week. White19 showed effects. 200-300 mins/week peaked the benefit (3-5 hours). Self-report of health and wellbeing.
• 4-5 days Ulrich84. Days of window (on green space) being there. No data on how much time the patients spent looking at the trees outside.

Duration of beneficial effect

Opezzo14, who measured boosts to "creativity", report that their effect lasted only 2 mins. beyond the end of the intervention. Ulrich84 looked at the benefit of having a window that looks on to greenspace for 4-5 days, but says nothing about whether the effect stopped as soon as they went home; or whether further effects are to be had depending on the room outside the hosptial they move to after they leave.

Abbreviated bibliography

• Alvarasson10 doi: 10.3390/ijerph7031036
• Baxter19 doi: 10.1037/cap0000145
• Bergomi13 doc.rero.ch/record/315958/files/12671_2012_Article_110.pdf.
• Berman08 doi: 10.1111/j.1467-9280.2008.02225.x
• CDix20. See above on this page under "Some projects here on green space"; direct link to a PDF
• Craig16 doi: 10.1186/s40101-016-0083-9
• Dadvand15 doi: 10.1073/pnas.1503402112
• Hahn08 doi: 10.1016/j.jenvp.2007.10.008
• Hartig97 doi: 10.1080/02815739708730435
• Han18 doi: 10.1080/00222216.2018.1505159
• Houlden18 doi:10.1371/journal.pone.0203000 A review of greensp. wellbeing effects.
• Jiang19 doi: 10.1177/0013916518788603
• Kaplan95 doi: 10.1016/0272-4944(95)90001-2
• Kaplan01 doi: 10.1177/00139160121973106
• Kaplan10 doi: 10.1177/1745691609356784
• Kernan10 doi: 10.1111/j.1099-0860.2009.00249.x
• Kjellgren10 doi: 10.1016/j.jenvp.2010.01.011
• Manley99 doi: 10.1016/S0028-3932(98)00127-4 About the SART test.
• Manley05 doi: 10.1016/B978-012375731-9/50059-8 About the SART test.
• Mathew19 doi: 10.1038/s41598-019-44097-3
• McMahan18 digitalcommons.wou.edu/fac_pubs/45/
• Nieuwenhuijsen14 doi: 10.1136/bmjopen-2014-004951
• OCallaghan14 Online access
• Opezzo14 doi: 10.1037/a0036577
• Paterson15. See above on this page under "Some projects here on green space"; PDF
• Richardson19: doi: 10.3390/su11123250
• Schutte17 doi: 10.1177/0013916515603095
• Snell19 doi: 10.1177/0013916518787318
• StewartBrown09 doi: 10.1186/1477-7525-7-15
  
  Stewart-Brown, S., Tennant, A., Tennant, R., Platt, S., Parkinson, J., Weich, S., 2009. "Internal construct validity of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS): a Rasch analysis using data from the Scottish Health Education Population Survey" Health and Quality of Life Outcomes vol.7 no.15.
• Taylor09 doi: 10.1177/1087054708323000
• Tennessen95 https://tinyurl.com/y24reuyq
• Ulrich84 Science 1984 vol.224 april-27 issue:4647 pp.420-421
• Wallner18 doi: 10.3390/ijerph15061205
• Watson88 doi: 10.1037/0022-3514.54.6.1063

Time of day effects on school tests that tries to use attention restoration as an explanation

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