View from the top (2006)

MacLean, E., Roberts Prior, S.

Abstract

Across both conditions, monkeys showed a strong preference for the upper-row cage indicating that elevation was more important than illumination in guiding location preference. Although monkeys did increase the amount of time that they spent in the lower row during periods of reversed lighting, this trend was not significant. Nonetheless, we do not interpret this result as evidence that sufficient lighting is not important to captive monkeys. Rather, we believe that monkeys' consistent preference for the upper-row reflects the paramount importance of access to elevated space.