Children with ADHD (attention deficit hyperactivity disorder) cannot maintain a normal level of performance the way most can. The symptoms fluctuate and can even temporarily disappear. Researchers aim to find a pattern to the fluctuations, and one of the theories used to tackle the question is attention restoration theory (ART). ART  is originally used to explain why exposure to natural environments causes a sense of rejuvenation and indicates that people perform better on objective measures of attention after spending time in or viewing natural landscapes.

This study (2009) examined effects of exposure to different environments on attention in children with ADHD. 17 participants diagnosed with ADD or ADHD (aged 7–12) were exposed to three environments 1 week apart via a 20 minute guided walk: a city park, downtown urban settings and neighbourhood setting, after which their attention was measured using Digit Span Backwards (DSB). Before the walks, children performed puzzles indoors to cause attention fatigue so that the measures would reflect recovery from attentional fatigue. General information of participants and opinions about the walks were also collected.

The study showed, that DSB scores of children with ADHD

• varied by setting (p = 0.02)
• were significantly better after park exposure compared to the neighbourhood (p = 0.007) or downtown settings (p = 0.02)
• were not significantly different after the neighborhood and downtown settings (p = 0.64)

DSB scores were 0.7 of a digit better after the park exposure than after the neighbourhood exposure, and 0.6 of a digit better than after the downtown exposure. The study concludes, that 20 minute walk in park was sufficient to elevate attention performance not only in regular people but for the attention deficient too. Nature can act as a safe, inexpensive, widely accessible tool for managing ADHD symptoms.