Manipulating the affiliative interactions of group-housed rhesus macaques using positive reinforcement training techniques

Social housing, whether continuous, intermittent, or partial contact, typic ally provides many captive primates with opportunities to express affiliati ve behaviors, important components of the species-typical behavioral repert oire. Positive reinforcement training techniques have been successfully emp loyed to shape many behaviors important for achieving primate husbandry goa ls. The present study was conducted to determine whether positive reinforce ment training techniques could also be employed to alter levels of affiliat ive interactions among group-housed rhesus macaques. Twenty-eight female rh esus were divided into high (n = 14) and low (n = 14) affiliators based on a median split of the amount of time they spent affiliating during the base line phase of the study. During the subsequent training phase, half of the low affiliators (n = 7) were trained to increase their time spent affiliati ng, and half of the high affiliators (n = 7) were trained to decrease their time spent affiliating. Trained subjects were observed both during and out side of training sessions. Low affiliators significantly increased the amou nt of time they spent affiliating, but only during nontraining sessions. Hi gh affiliators on the other hand, significantly decreased the amount of tim e they spent affiliating, but only during training sessions. These data sug gest that positive reinforcement techniques can be used to alter the affili ative behavior patterns of group-housed, female rhesus monkeys, although th e two subgroups of subjects responded differently to the training process. Low affiliators changed their overall behavioral repertoire, while high aff iliators responded to the reinforcement contingencies of training, altering their proximity patterns but not their overall behavior patterns. Thus, po sitive reinforcement training can be used not only as a means to promote sp ecies-typical or beneficial behavior patterns, but also as an important exp erimental manipulation to facilitate systematic analyses of the effects of psychosocial factors on behavior and potentially even immunology. (C) 2001 Wiley-Liss, Inc.