Inferential Reasoning in the Visual and Auditory Modalities by Cotton-Top Tamarins (Saguinus oedipus)

Nonhuman primate species appear to vary markedly in inferential reasoning abilities as measured by a classic inference-by-exclusion cup task. Even within species, individuals who can solve the cup task in the visual domain often struggle to use analogous auditory cues. Here we tested five cotton-top tamarins (Saguinus oedipus), cooperatively breeding New World monkeys that use both visual and auditory information when foraging, to investigate whether they might be able to solve the inference-by-exclusion task in both domains. Four subjects completed the testing series in both domains. Although three subjects performed well in the visual task, only one subject chose food location significantly above chance in response to positive auditory cues. These results demonstrate the first evidence of inferential reasoning abilities in a callitrichid species, while also revealing the performance asymmetry between the visual and auditory modalities observed in many other primates.