From colour photographs to black-and-white line drawings: an assessment of chimpanzees’ (Pan troglodytes’) transfer behaviour
Over two experiments, we investigated the ability of two adolescent and two adult chimpanzees to generalise a learnt, pictorial categorisation to increasingly degraded and abstract stimuli. In Experiment 2, we further assessed the ability of the adolescent chimpanzees to engage in open-ended categorisation of black-and-white line drawings. The current results confirmed and extended previous findings, showing that sub-adult chimpanzees outperform adult chimpanzees in the categorisation of pictorial stimuli, particularly when the stimuli are more degraded and abstract in nature. However, none of the four chimpanzees showed positive transfer of their category learning to a set of black-and-white line drawings, and neither of the adolescent chimpanzees evidenced reliable open-ended categorisation of the black-and-white line drawings. The latter findings suggest that both sub-adult and adult chimpanzees find it difficult to recognise black-and-white line drawings, and that open-ended categorisation of black-and-white line drawings is challenging for chimpanzees.
KeywordsCategorisation Chimpanzees (Pan troglodytes) Generalisation Line drawings Picture recognition
The authors wish to thank Charlotte Rahn and the B-Chimpanzee keepers of Zoo Leipzig for their help in conducting the present experiments. James Close further wishes to thank the Deutscher Akademischer Austausch Dienst (DAAD) for its support during his time at the Max Planck Institute for Evolutionary Anthropology.
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