Københavns Universitet
Uafhængig af ledelsen

PhD thesis defense

Matt P. Stevenson defends his thesis on children with ADHD exposed to nature

PhD thesis defense — Forest and Landscape College


Date & Time:

The Auditorium, Forest and Landscape College ('Skovskolen'), Nødebovej 77A, 3480 Fredensborg

Hosted by:
Forest and Landscape college, Department of Geosciences and Natural Resource Management


Matt P. Stevenson defends his thesis,

Green Matter: How exposure to natural environments improves cognitive functioning in children with and without Attention Deficit/Hyperactivity Disorder

Professor MSO Palle Madsen, Department of Geosciences and Natural Resource Management
Senior Researcher Peter Bentsen, Steno Diabetes Center Copenhagen and Affiliated Professor at Department of Geosciences and Natural Resource Management
Associate Professor Theresa Schilhab, University of Aarhus

Assessment Committee:
Professor Terry Hartig, Uppsala University, Sweden
Professor Dr. Agnes E. van den Berg, University of Groningen, The Netherlands
Associate Professor Sus Sola Corazon (chair),  Department of Geosciences and Natural Resource Management

Attention Restoration Theory (ART) proposes that exposure to nature can support the human brain by inducing a period of restoration that is necessary for overcoming the effects of mental fatigue. However, studies of this effect in children are rare. The current thesis aimed to investigate how natural environments influence the cognitive processes of children with and without attention deficit/hyperactivity disorder (ADHD). Firstly, a systematic review and meta-analysis was conducted to assess the current evidence surrounding ART across all age groups. Results revealed that exposure to nature can lead to improvements in working memory, cognitive flexibility, and attentional control, while the lack of research in children was also confirmed. Secondly, the results of a randomised crossover trial showed that a walk in a natural environment improves response speed and stability on the Attention Network Task (ANT), compared to a walk in a built environment. Using mobile eye-tracking glasses, it was also found that children fixated more often while walking in natural environments, which may reflect an ease in shifting attentional focus or a higher level of fascination induced by viewing natural scenery. Thirdly, a pre-registered, double-blinded, placebo-controlled, randomised, two-by-two crossover trial was conducted to compare the effect of exposure to natural environments with the effect of medication to improve cognitive symptoms in children with ADHD. The results showed that the environment had no influence on cognitive performance, while medication improved performance on three out of four outcome measures derived from the ANT. The results suggest that the effect exposure to nature has on children with ADHD may be more elusive and complex than generally assumed. However, future studies will benefit from methodological insights gained from this thesis. Finally, a theoretical extension of ART is proposed as a new understanding of how exposure to natural environments can improve brain function, based on the current evidence. The Cognitive-Energetic Model of Restoration proposes that mental fatigue and stress can be overcome simultaneously through exposure to nature by improving the regulation of so-called ‘energetic factors,’ arousal and effort. This framework may be particularly useful in understanding the effect of nature on children’s functioning, as the control of arousal and effort seems particularly important for mental restoration in this agegroup.

The thesis is available for inspection at the PhD administration office 04.1.413 at Øster Voldgade 10, 1350 CPH K