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Green space effects
Department of Psychology,
University of Glasgow.
This page is to summarise and hold pointers about the "Green space" phenomenon.
I feel we can call it a phenomenon because there are too many reports of
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
have all supervised undergraduate research projects in this area.
There have been at least two student projects showing that primary school
pupils are significantly better at concentrating on school work after a visit
to a green space, than after a break of some other kind. Such work elsewhere
has also been published e.g. Wallner18.
- 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
(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
(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
Some lit. refs on green space
Here are (only) a few published papers on the green space phenonmenon,
arranged to illustrate a series of distinct ideas, and so to give some idea of
the variety of work in the area.
2. The most often cited "theory" is Attention Restoration Theory
(ART). This focusses attention on the idea that the ability to control one's
attention is a finite resource that diminishes (fatigues) as it is used, and
how green space exposure can replenish attention, and more generally a variety
of cognitive abilities.
[This is an idea about the cause of green space effects (depletion of a
finite mental resource); and also of specific effects (lower cognitive
performance of various kinds, until restoration occurs).]
1. Some of the early papers report medical effects.
[The first idea about the effects of green space.]
Note that in this first example, it is a view through a window,
not being outside in the green space, that is beneficial.
- Ulrich, R. (1984) "View through a window may influence recovery
from surgery" Science 224 (4647), pp.420-421.
PDF via GU library
The introduction in the next article, which is from a medical journal, cites
reports of numerous types of medical benefit from green space: longevity,
cardiovascular diseases, people's self-reported general health, mental health,
sleep patterns, recovery from illness, social health aspects and birth
outcomes. But it emphasises that little is known of the mechanisms underlying
- Nieuwenhuijsen MJ, Kruize H, Gidlow C, et al. (2014)
"Positive health effects of the natural outdoor environment in typical
populations in different regions in Europe (PHENOTYPE): a study programme
BMJ Open 2014;4:e004951.
- 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.
- Kaplan, S. and Berman, M.G. (2010)
"Directed Attention as a Common Resource for Executive Functioning and
Perspectives on Psychological Science 5(1) 43-57
- 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
Int. J. Environ. Res. Public Health vol.15 1205
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.]
But perhaps we could also connect this to the concept of flow.
Different kinds of attention. Novelty yet irresponsibility: thus avoiding
both boredom and stress.
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
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
[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
6. A general effect on well-being as well as on health and on cognitive
[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.
"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
[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
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.
- 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
Carol Craig's centre (materials written roughly 2018). Entry by
a Jigsaw diagram index
a more textual index
Particularly these articles:
What is it about "green space" that determines its effectiveness?
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
All of these have been shown to have (some) green space effects.
- Being outdoors
- Seeing it through a window
- Viewing still pictures
Studies of whether window glass makes a difference
Hahn08 paper raises the question
Trait measures of nature-relatedness
There are several measures of "nature-relatedness"
(and a wikipedia entry lists more with references):
From an experimental psychology perspective, however, they are disappointing.
- 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
- 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.
- 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
Bergomi13 reviews self-report measures of mindfulness.
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
There is questionnaire based on self-report of feelings of restorativeness:
the Perceived Restorativeness Scale (PRS).
Hartig97 discusses it; Han18 reviews it.
- 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).
Snell19 gives some details of these; as does Alvarasson10.
- 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
- Changes in Blood Pressure.
Attention control i.e. ability to direct attention
Snell19 gives some details of these; as does CDix20; and many other papers e.g. Berman08.
- 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.
Manley99 discusses SART; Kaplan10 deals with SART briefly.
Opezzo14 used, describes, and gives references for three different measures,
which capture different aspects of creativity.
One test is for "Divergent thinking", using GAU (Guilford's Alternate
"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
A cross-sectional study does a single one-time questionnaire of a sample, and
then looks for correlations (in this field) between (1) how often the
participant (P) looks out of the window and what type of view they see, with
(2) their wellbeing, stress etc.
Mathew19 and Kernan10 are of this kind.
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
Active intervention on two occasions: e.g. over a week
While these are possible and have been done by students, it is more effort, and
usually you lose a part of your participants who don't return for the second
session. Some of my most impressive student projects have nevertheless been
done this way (though not as a level 3 quant. project); and one of them was in
fact done online for reasons other than lockdown.
One occasion: immediate effect within 30 - 60 mins
This would be practicable in a one-occasion online study, where you take a
participant for an hour or less, and apply both pre/post measures and one or
more interventions. CDix20 is an example.
Some time durations of interventions:
for the length of green space exposure in various studies
There is no standard length of how long someone needs to be exposed to green
space for there to be a reliable effect. (In many studies, this is the length
of the intervention, which is preceded by a baseline pre-test; and followed by
- 3:40 min. video, with soundtrack. Curently under test.
This video is a composite comprised of materials from the open access site
- 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
A lot of papers seem to assume the effect is lasting, but in fact this is a
key issue, handled poorly in many experimental designs. Simply expecting it is
a "restorative" actually implies that it will wear off soon, as a rest in the
middle of a walk does.
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.
Research questions I would like to be answered if money, time and
effort were not a problem ...
- More work on views from windows. How long people spend looking out
of them, ...
- Vary angles of view, nearness, crowdedness etc. as factors in whether
greenspace vs urban space matters.
- What seems to work as "green space" Bare rock, deserts? Fields of
Volcanic ash and rock with nothing growing?
Empty ocean? Emptiness, or varied scenes? Reminders of types of scene that
individuals like (but others may not)?
Does "green space" work if it's dark?
The important papers on this page I have given a full reference for, in the
subsection where they are discussed. (They are also in this section in
abbreviated form.) To save myself typing and fiddling about, here is an
abbreviated list of more references. Each paper is referred to by tags like
"Kernan10", which means that the first author's name is Kernan and date of
publication is 2010; and the DOI is given, so you can get at the paper with a
single click, at least usually enough to see the title and authors and perhaps
abstract. However to get at a full copy you still have work to do in
navigating the library's access to the paper.
- Alvarasson10 doi: 10.3390/ijerph7031036
- Baxter19 doi: 10.1037/cap0000145
- 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
- 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
- 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
Science 1984 vol.224 april-27 issue:4647 pp.420-421
- Wallner18 doi: 10.3390/ijerph15061205
- Watson88 doi: 10.1037/0022-35188.8.131.523
Time of day effects on school tests that tries to use attention
restoration as an explanation
Sievertsen,H.H., Gino,F. and Piovesan,M. (2016)
"Cognitive fatigue influences students' performance on standardized tests"
This discusses a) "cognitive fatigue" in children cf. "attention restoration";
b) A time of day effect on test scores;
c) A 20-30 min. rest immediately prior to test also shows an effect.
We identify one potential source of bias that influences children's
performance on standardized tests and that is predictable based on
psychological theory: the time at which students take the test. Using test
data for all children attending Danish public schools between school years
2009/10 and 2012/13, we find that, for every hour later in the day, test
scores decrease by 0.9% of an SD. In addition, a 20- to 30-minute break
improves average test scores. Time of day affects students' test performance
because, over the course of a regular day, student's mental resources get
taxed. Thus, as the day wears on, students become increasingly fatigued and
consequently more likely to underperform on a standardized test.
Note however, that this study has a VERY tiny effect size (but reached
significance due to the huge sample size): so not only is this not about a
"green" intervention, but it seems too small to bother about.
Zhao project happiness at UBC
The survey questions
How are you feeling?
Welcome! This survey is about your immediate experiences and takes about 5
minutes to complete. You can participate anytime, anywhere on UBC Vancouver or
Okanagan campus, and as many times as you want!
Scales are mostly 0...10 or -10...0...+10, with 2 anchor points.
- How happy are you feeling at this moment?
- How stressed are you feeling at this moment?
- How energetic are you feeling at this moment?
- How anxious are you feeling at this moment?
- How relaxed are you feeling at this moment?
- How upset are you feeling at this moment?
- How tired are you feeling at this moment?
- How confident are you feeling at this moment?
- How busy are you at this moment?
- How beautiful is your current environment?
- How clean is your current environment?
- How quiet is your current environment?
- How spacious is your current environment?
- How hot is your current environment?
- How safe is your current environment?
- How comfortable is your current environment?
- How healthy are you feeling these days?
- How long have you been at UBC? (Please specify how many years and months)
- How satisfied are you with your life these days?
- How much financial stress do you feel on a day-by-day basis?
- Are you currently with any friends right now? If so, how many?
- What were you doing just before taking the survey?
- What is your gender?
- Which year were you born?
- Please indicate your exact location on the map: ...
Web site logical path:
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