What are the relative attention restoration values of natural settings compared to other settings?
Are the impacts different for different groups of people (e.g. adults, children, those with mental health issues or learning disabilities)?
Are the impacts different for different prior demands (e.g. people with stressful jobs)?
Are the impacts different for different types of natural settings (e.g. parks vs. open countryside; seascapes vs. landscapes; images vs. actual exposure)?
Are the impacts different for different types of exposure/engagement (e.g. active vs. passive; real vs. virtual; duration and frequency of exposure)?
Are the impacts different for people with different opinions about natural settings (e.g. preferences; usual exposure; connectedness to nature)?
To what extent could any differences be explained by confounding factors (e.g. change of setting (novelty); any physical activity undertaken; negative impact of urban settings; manipulation of settings)?
Do the impacts persist long term?
A full search strategy will be developed by an information specialist (AB) in consultation with the wider team. No relevant subject headings were identified so free text searching will be used including the following key words:
The following resources will be searched from 1989 (date of seminal work on ART) to the present day:
PsycINFO on OVIDSP
MEDLINE on OVIDSP
EMBASE on OVIDSP
AMED on EBSCOHost
Web of Knowledge on Thomson (for environmental/architectural papers)
Environment Complete on EBSCOHost
A citation search on the early Kaplan work (1989, 1995) will be used to search for more relevant papers in Web of Science.
Kaplan, R. and S. Kaplan (1989). The experience of nature: A psychological perspective. New York, Cambridge University Press; US.
Kaplan, S. (1995). The restorative benefits of nature: Toward an integrative framework. Journal of Environmental Psychology 15(3): 169-182.
Reference lists of all included studies will be scanned to check for further relevant articles based on their titles and abstract reading. Forward citation chasing on included studies will also be undertaken. In addition, researchers and institutions associated with this field of study will be contacted to find eligible on-going or completed studies.
Types of study to be included
Study design: Experimental studies only. Relevant comparative study designs, including case/control studies, crossover studies and natural experiments. With the exception of some natural experiments, studies should include ‘before and after’ measures of attention.
Exclusions: Studies that only measure perceived attention (e.g. using Perceived Restoration Scale) or other self-reported cognitive outcomes. Studies that examine stress reduction and not attention restoration relating to natural settings.
Screening of abstracts (phase 1) and full texts (phase 2) for eligible studies will be completed independently by two members of the review team.
Condition or domain being studied
This review will examine the relative attention restoration values of natural settings compared to other settings. In other words, does exposure to natural settings (either spending time in natural environments or viewing images of natural environments) confer greater benefits compared to non-exposure or exposure to alternative/urban settings?
Adults and children (all ages).
Performance of attention tasks following engagement with any natural setting. The levels of engagement could include actual engagement: active (such as walking in nature) or passive (such as looking at a natural view); or virtual engagement (such as watching video or images of natural environments).
Performance of the same attention tasks following engagement with any non-natural setting. The levels of engagement could include actual engagement: active (such as walking in a city) or passive (such as looking at an urban view); or virtual engagement (such as watching video or images of urban environments).
Attention Restoration Theory (ART) (Kaplan, 1989, 1995) suggests that mental fatigue and concentration can be improved by time spent in, or looking at nature. The capacity of the brain to focus on a specific stimulus or task (voluntary or directed attention) is limited and results in ‘directed attention fatigue’. ART proposes that exposure to natural environments encourages more effortless brain function (involuntary attention), thereby allowing it to recover and replenish its directed attention capacity. This may be seen in improved ability to engage with tasks that require concentration, memory, responsiveness etc.
The natural environment must have four properties in order to provide this restorative effect, according to Kaplan: extent (the scope to feel immersed in the environment); being away (providing an escape from habitual activities); soft fascination (aspects of the environment that capture attention effortlessly); compatibility (the individual must want to be exposed to the environment and appreciate the environment). It is thought that soft fascination plays the key role, with the other three properties enhancing or sustaining fascination.
Although ART is a widely cited concept in the literature, it is unclear how much empirical evidence there is to support this theory.
Measures of attention including concentration, memory, response-control, impulse inhibition etc. Tests include Necker Cube Pattern Control, Stroop, Attention Network Test, Digit Span Forward/Backward, Sustained Attention to Response Test, etc. Only studies using objective measures/tests will be included.
Measures of physiological effect (e.g. blood pressure) and emotional effect (any validated measures of mood, stress etc.) – studies measuring these will only be included if they also measured attention.
Data extraction, (selection and coding)
The following data will be extracted from included studies: study design, population characteristics (age, gender, prior demands/stress, mental health needs/conditions), setting/s characteristics (rural/urban, blue/green), type of exposure and engagement with setting/s, duration of exposure and engagement, comparison/control group, measures of attention, outcomes, duration of follow up, proposed causal mechanisms.
Data extraction will be undertaken by one reviewer and checked by a second using a bespoke Excel database.
Risk of bias (quality) assessment
Studies will be appraised using the CRD quality criteria to assess for potential bias. The critical appraisal checklists from the Critical Appraisal Skills Programme (CASP) will be used to assess the rigour, credibility and relevance of included studies.
Strategy for data synthesis
Where study and outcome homogeneity permits, effect sizes will be pooled using random effects meta-analysis. The meta-analysis will be carried out using Review Manager Software (RevMan, 2011) based on the data from included studies. If this is not feasible, we will use formal methods of narrative synthesis.
Analysis of subgroups or subsets
Analysis will be sensitive to potential different impacts on specific subgroups of people, such as those with ADHD or other learning difficulties, adults and children. Different types of exposure (active vs. passive; real vs. virtual) will also be considered.
Publication in academic journal in the field of environmental psychology. A briefing document about the findings will also be developed.
Contact details for further information
Dr Ruth Garside
European Centre for Environment and Human Health
Royal Cornwall Hospital
Truro, TR1 3HD.
Organisational affiliation of the review
European Centre for Environment and Human Health, University of Exeter Medical School
Dr Ruth Garside, University of Exeter Medical School Mrs Heather Ohly, University of Exeter Medical School Dr Mathew White, University of Exeter Medical School Dr Ben Wheeler, University of Exeter Medical School Ms Alison Bethel, University of Exeter Medical School Ms Sarah Bell, University of Exeter Medical School
Anticipated or actual start date
03 June 2013
Anticipated completion date
29 November 2013
The European Centre for Environment and Human Health (part of the University of Exeter Medical School) is supported by investment from the European Regional Development Fund and the European Social Fund Convergence Programme for Cornwall and the Isles of Scilly.
Conflicts of interest
Subject index terms status
Subject indexing assigned by CRD
Subject index terms
Attention; Humans; Memory, Short-Term; Nature
Stage of review
Date of registration in PROSPERO
03 July 2013
Date of publication of this revision
03 July 2013
Stage of review at time of this submission
Piloting of the study selection process
Formal screening of search results against eligibility criteria
Risk of bias (quality) assessment
PROSPERO This information has been provided by the named contact for this review. CRD has accepted this information in good faith and registered the review in PROSPERO. CRD bears no responsibility or liability for the content of this registration record, any associated files or external websites.