Reinhardt, V., Reinhardt, A., Houser, D. 1987. Prompted progression order in a troop of captive rhesus monkeys. Folia Primatologica 48(3-4), 121-124.

The 22 animals were prompted - shouting, threatening with sticks - to exit into a transfer cage and subsequently weighed one a month. The animals had to overcome fear before leaving their home pen. Nonetheless, they left in a well-defined sequence that was remarkably stable throughout the 10-month test period. An individual's position in this exit order was dependent on his/her age but not on his/her dominance status. It was suggested that the monkeys gradually learned with age to master their fear with the prospect of quickly returning to their home pen.