can be decreased, and suggests that exposure to the natural environment may aid in the reduction of DAF symptoms. A number of researchers have investigated Directed Attention Fatigue recently. Leading contributors include Rachel and Stephen Kaplan, environmental psychologists at the University of Michigan. Rachel and Stephen Kaplan are credited with much of the research relating to Directed Attention Fatigue and were the first to discover that extended periods of focused attention can lead to DAF. Their research suggests that Directed Attention Fatigue can be alleviated with exposure to nature. Together, the Kaplans devised the Attention restoration theory (ART), which states that a person is better able to maintain focused directed attention after spending time in the natural environment. A number of studies have been performed that specifically focus on Directed Attention Fatigue experienced by cancer patients. Such studies suggests that the DAF experienced by cancer patients following surgery improves significantly through outdoor restorative activities for 20 minutes per day. Similarly, it has been discovered that even brief amounts of time spent on a busy metropolitan street can affect one's ability to maintain focus on a given task. Experimental findings suggest that spending time in a natural environment or even looking at pictures of nature can improve maintenance of directed attention. The Landscape and Human Health Laboratory (LHHL) has completed studies examining the complex relationship between people and their environment. Researchers here discovered the correlation between Directed Attention Fatigue, irritability and aggression. Their findings suggest that people deprived of the restorative effects of nature display more aggressive qualities. Results also demonstrate that communities with several trees and other natural areas tend to be stronger, safer and house residents with a higher attention level. More recent experimentation done at the LHHL suggests that children possessing attention deficits increase their attention level after walking outdoors. According to this and much other research that has been performed regarding directed attention fatigue, the brain's ability to maintain directed attention is heightened after exposure to nature. See also Attention Attention span Environmental psychology Ego depletion Human multitasking References Neuropsychology Neurological disorders Symptoms and signs of mental disorders