This experimental study provided a test of the predictions of the Attention Restoration Theory (ART). Twenty-two university students participated in a study designed “to parse out the differences between bottom-up and top-down processing by directly manipulating the attentional requirements across conditions.” Bottom-up processing occurs when an individual's attention is engaged without effort. This is in contrast to top-down processing which requires effort. ART predicts that nature engages the bottom-up, effortless attention system, giving the top-down, effortful attention system time to rest; nature is therefore restorative of fatigued attention function.
Each participant completed directed attention tests under three different environment conditions: the Control Condition, the Nature Condition, and the Perturbation Condition. For each condition, participants were required to walk for 10 minutes. For the Control Condition, participants walked on a treadmill with just a blank white screen in their field of view. For the Nature Condition, participants walked on a treadmill while experiencing a simulated nature walk through a forest.The Perturbation Condition was identical to the Nature Condition except for two differences which required top-down processing during the walk. The first difference required participants to respond with arm movements to simulated birds flying toward them. The second difference required participants to make expected and unexpected adjustments to their balance while walking on a simulated bumpy and hilly terrain.
Participants completed two directed attention tests (the backward digit span test and the Necker cube test) before and after engaging in each of the environment conditions. Before walking on the treadmill, they completed 20 mins of the Stroop color-word interference test to fatigue their attention. The Stroop requires the participant to either say the color word or the color the word is printed in when the color word and the ink color do not match ("red" printed in blue ink). Findings showed that the Nature Condition produced a significant improvement in directed attention performance compared to the control and perturbation conditions. This was expected, as Attention Restoration Theory (ART) research has produced many similar findings. This study adds to the ART literature by exploring the restorative effects of physical activity engagement in a simulated natural environment. Other studies with simulated natural environments used only passive engagement. This study also adds to the ART literature by showing that top-down processing in a simulated natural environment tends to nullify the restorative effects of a natural environment.
This research offers some practical insights about how to enhance cognitive functioning in different environments. In university settings, natural, restorative environments outdoors and simulated natural environments indoors would enable students, professors, and staff to restore directed attention and thus support cognitive performance. “If these findings are generalizable to the general public, work environments and city designs may consider implementing more natural or simulated natural environments as well.”