Jiang, He, Chen, Larsen, and Wang evaluated how driving on a freeway through various sorts of urban environments influences driver experience. They found via 90-minute simulations of environments through which study participants “drove” at the legal speed limit (70–120 km/hour) that: “The summarized mental status measure is the average value of the seven measures of negative mental status (boredom, anger, frustration, tension, anxiety, avoidance, mental fatigue). . . . the tree-regularcondition evoked significantly lower levels of negative mental status than all other conditions. . . . The barrenand shrub-randomconditions evoked significantly higher levels of negative mental status than the other four conditions, and there is no significant difference between barrenand shrub-random.The turf, shrub-regular, and tree-randomconditions ranked from 3nd to 5th on evoked level of negative mental status, but none of the comparisons between them are significant. . . . Landscapes with greater levels of greenness, such as those with a vertical outline of trees, are far more restorative.” So, as greenness increases (from barren to shrub and, finally, to tree) lower levels of negative mental status are perceived by the drivers. Also, when greenness levels are roughly equivalent, views with greater visual complexity (random arrangements were more complex than regular ones) were tied to greater levels of negative mental status. In random test conditions there was more species diversity and spatial variation in plant arrangement than in regular ones but in both cases (for example, tree-regular and tree-random) similar numbers of trees or shrubs were present. The researchers recommend that barren landscapes beside freeways, those without even turf in place, be avoided.
Bin Jiang, Jibo He, Jielin Chen, Linda Larsen, and Huaqing Wang. “Perceived Green at Speed: A Simulated Driving Experiment Raises New Questions for Attention Restoration Theory and Stress Reduction Theory.” Environment and Behavior, in press, https://doi.org/10.1177/0013916520947111