Researchers recently conducted an open diffusion experiment to explore how capuchin monkeys learn novel behaviors, shedding light on the roles of social learning, observation, and affiliative relationships. The study, published in Proceedings of the National Academy of Sciences of the United States, employed a lift-pull task that required monkeys to manipulate a blue plate or a green knob on a specially designed apparatus to release a food reward. The apparatus, a matte white acrylic box, featured two functional components—a blue plate that could be lifted and a green knob that could be pulled. Both actions triggered the release of an identical food reward mixture of corn, peanuts, and raisins into a tray below.
To control the initial learning process and prevent task monopolization, researchers seeded each group with a trained demonstrator. In one group (JB), a mid-ranking adult female was trained to use the lift action, while in another group (PF), a mid-ranking juvenile male was trained to use the pull action. After the initial seeding phase, the apparatus was presented to each group for 14 days, with both options available for manipulation. Two video cameras captured all task manipulations and the surrounding area within a 5-meter radius.
The findings revealed that observation opportunities were critical for task acquisition. Individuals were more likely to learn the task if they closely observed a conspecific successfully manipulating the apparatus. As Camila Galheigo Coelho, one of the study’s primary authors, explained, “Our observations fed into a mathematical model that showed that monkeys learn from others mainly through direct observation, by looking closely at another individual doing the task.”
The additive model suggested that observation alone could lead to direct learning, while the multiplicative model indicated that a demonstrator’s behavior could enhance the likelihood of learning through indirect mechanisms like stimulus enhancement. Affiliative relationships outside of task interactions also played a significant role in shaping learning pathways. The analysis revealed that social tolerance and preexisting affiliative bonds increased the likelihood of observation and subsequent learning. Monkeys engaged in collective activities, such as grooming or cofeeding, were more likely to learn from one another. This finding underscores the importance of social cohesion in facilitating information transfer within groups.
The capuchin monkey study demonstrates how direct observation and social tolerance facilitate the spread of novel behaviors. By integrating behavioral experiments with network analysis, researchers uncovered the nuanced dynamics of learning and information transfer in social groups.
Sources: Proceedings of the National Academy of Sciences of the United States, EurekAlert
