In a study at a Chicago public housing development, girls living in apartments with greener, more natural views scored better on tests of self-discipline than those living in more barren but otherwise identical housing. Boys showed no link between test scores and the amount of nature near home, most likely because they spend less time playing in and around their homes.
Taylor, Andrea Faber, Frances E. Kuo, and William C. Sullivan. (2002). Views of nature and self-discipline: Evidence from inner city children. Journal of Environmental Psychology, 22(1), 49-63.