“…Chimpanzees who were transferred to a larger and more naturalistic environment showed a decrease in abnormal behavior and an increase in general activity (Brent, Lee, & Eichberg, 1991;Clarke, Juno, & Maple, 1982). Other studies have reported that environmental complexity was as important as size in altering primate behavioral patterns (Traylor-Holzer & Fritz, 1985;Van Hooff, 1967;Wilson, 1982). Exceptions to this pattern of positive effect of increased cage size and complexity include studies of singly housed primates in minimalist conditions (Crockett, Bowers, Sackett, & Bowden, 1993;Crockett et al, 1995;Crockett, Mikashimoji, & Bowden, 2000;Jorgenson, Kinsey, & Novak, 1997;Line, Morgan, Markowitz, & Strong, 1990).…”