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Abstract
Analogical reasoning involves recognizing similarities among object relations when the objects themselves are dissimilar. It has been argued that humans only share the capacity for this kind of reasoning with apes that have had prior token or language training. This study investigated whether capuchin monkeys can use analogical reasoning in order to solve a three-dimensional search task that was modeled from a similar methodology used in the developmental literature. The task involved hiding a food item under one of two or three opaque plastic cups of different sizes, and then allowing the subject to search for food hidden under the cup of analogous size in their own set of cups. Four monkeys were first trained to perform basic match-to-sample with three cups, and then were exposed to a series of relational matching tasks. If subjects reached criterion on these relational matching tasks, they were exposed to relational transfer tasks involving novel stimuli. Three of the monkeys failed to reach criterion on the basic relational matching tasks and therefore were not tested further. One monkey, however, revealed above-chance performance on all tasks, including the series of transfer tasks with novel stimuli. This evidence suggests that, contrary to previous arguments, a member of a New World monkey species with no language training has the capacity to solve an analogical problem.