The use of positive reinforcement training to reduce stereotypic behavior in rhesus macaques

Stereotypic behavior is a pervasive problem for captive monkeys and other animals. Once this behavior pattern has started, it can be difficult to alleviate. We tested whether or not using positive reinforcement training (PRT) can reduce this undesired behavior. Subjects for this study were 11 adult, female rhesus macaques (Macaca mulatta) with a history of locomotor stereotypy (e.g., pacing, bouncing, and somersaulting). We assessed baseline levels of stereotypic behavior and then utilized PRT to train six animals to touch a target and accept venipuncture. The other five monkeys served as controls. We assessed stereotypic behavior 1 week a month for 4 months, on days in which the monkey was not trained. Trained animals showed a significant reduction in stereotypic behavior after 1 month of training, compared to control monkeys (Mann–Whitney U = 28.00, P = 0.02). These group differences did not persist after the first month (Month 2: Mann–Whitney U = 19.50, P = 0.40, Month 3: Mann–Whitney U = 17.0, P = 0.71, Month 4: Mann–Whitney U = 17.00, P = 0.72). Still, the majority of the trained monkeys (n = 4) engaged in less stereotypic behavior at the end of the study compared to baseline. Thus, training may be an effective way to reduce stereotypic behavior, at least for some individuals.