Effect of pair housing on operant behavior task performance by rhesus monkeys (2002)

Hotchkiss, C. E., Paule, M. G.

Abstract

Sixteen young, male, individually housed, trained rhesus monkeys (2.5-5.5 years of age) performed a battery of behavior consisting of motivation (MOT), short-term memory and attention (STM), color and position discrimination (CPD), and learning (LRN) tasks. ... The subjects were divided into four age cohorts, and within each cohort two randomly selected subjects were pair housed, while eight age-matched controls remained individually housed. Pair-housed monkeys were separated [!] for behavior testing and feeding, but allowed access to each other approximately 20 h/day. The performance of the two groups of monkeys were compared for the 2 months prior to pairing, for a 2-month transition period as the pairs adjusted to the new housing situation, and for a 2-month period after the pairs had been established. Performance in the CPD and LRN task did not change over time in either group. For the MOT and STM task, the number of trials completed increased over the course of the study in the controls, but not in the pair-housed monkeys. Thus pair housing may have no affect on some operant behavior while affecting others in the same subjects.