Line, S. W., Morgan, K. N., Markowitz, H. et al. 1990. Increased cage size does not alter heart rate or behavior in female rhesus monkeys. American Journal of Primatology 20, 107-113.

The behavioral and heart rate responses of 10 female rhesus monekys to three different-sized, barren cages were measured. No differences were found and the conclusion drawn that the proposed [by USDA, 1985] changes in cage size will not improve well-being in any measurable ways.