The effect of a conspecific model on a capuchin monkey's (Cebus apella) choice between a certain, consistent food option and a risky food option
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This study examined the effect of the choices of a conspecific model on the decision making process of capuchin monkeys (Cebus apella) in the context of risk. In Experiment 1, I tested seven monkeys on their preference between an option awarding a fixed amount of food at a consistent rate (i.e. a certain choice) and an option that awarded double or nothing half the time (i.e. a risky choice). I found that six of them preferred the consistent option. I predicted that they would be influenced to shift their choice to the risky option when they saw a conspecific model receive a higher payoff for picking the risky choice. I found that while the model seemed to distract some of the monkeys, most of them stayed with their baseline preferences. In Experiment 2, I tested them with novel food containers to rule out the effect of prior experience with the options on their choices, predicting that in the absence of personal experience or information regarding the options, the monkeys would follow the model’s choice. The baiting contingency for the consistent and risky options was similar for the model and the subjects. Results were variable with some preferring the model’s choice, some preferring the consistent choice, and some showing no preference between the choices. Predicting a stronger effect of the model when the subjects saw him receive double the amount of food at a consistent rate, I tested the subjects using two more novel food containers (Experiment 3). Results were once again variable across individuals. I conclude that while there is evidence showing that capuchin monkeys attend to their own and a partner’s outcomes, they do not appear to keep track of their outcomes, or a partner’s outcomes, over a series of trials. They do however, seem to be distracted by the model. When faced with choices unfamiliar to them, some of them tend to follow the model’s choice indicating that prior experience can interfere with the influence of a social model.