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Orangutans (Pongo pygmaeus and Pongo abelii) understand connectivity in the skewered grape tool task


Mulcahy, Nicholas J; Schubiger, Michèle N; Suddendorf, T (2013). Orangutans (Pongo pygmaeus and Pongo abelii) understand connectivity in the skewered grape tool task. Journal of Comparative Psychology, 127(1):109-113.

Abstract

Great apes appear to have limited knowledge of tool functionality when they are presented with tasks that involve a physical connection between a tool and a reward. For instance, they fail to understand that pulling a rope with a reward tied to its end is more beneficial than pulling a rope that only touches a reward. Apes show more success when both ropes have rewards tied to their ends but one rope is nonfunctional because it is clearly separated into aligned sections. It is unclear, however, whether this success is based on perceptual features unrelated to connectivity, such as perceiving the tool's separate sections as independent tools rather than one discontinuous tool. Surprisingly, there appears to be no study that has tested any type of connectivity problem using natural tools made from branches with which wild and captive apes often have extensive experience. It is possible that such ecologically valid tools may better help subjects understand connectivity that involves physical attachment. In this study, we tested orangutans with natural tools and a range of connectivity problems that involved the physical attachment of a reward on continuous and broken tools. We found that the orangutans understood tool connectivity involving physical attachment that apes from other studies failed when tested with similar tasks using artificial as opposed to natural tools. We found no evidence that the orangutans' success in broken tool conditions was based on perceptual features unrelated to connectivity. Our results suggest that artificial tools may limit apes' knowledge of connectivity involving physical attachment, whereas ecologically valid tools may have the opposite effect.

Abstract

Great apes appear to have limited knowledge of tool functionality when they are presented with tasks that involve a physical connection between a tool and a reward. For instance, they fail to understand that pulling a rope with a reward tied to its end is more beneficial than pulling a rope that only touches a reward. Apes show more success when both ropes have rewards tied to their ends but one rope is nonfunctional because it is clearly separated into aligned sections. It is unclear, however, whether this success is based on perceptual features unrelated to connectivity, such as perceiving the tool's separate sections as independent tools rather than one discontinuous tool. Surprisingly, there appears to be no study that has tested any type of connectivity problem using natural tools made from branches with which wild and captive apes often have extensive experience. It is possible that such ecologically valid tools may better help subjects understand connectivity that involves physical attachment. In this study, we tested orangutans with natural tools and a range of connectivity problems that involved the physical attachment of a reward on continuous and broken tools. We found that the orangutans understood tool connectivity involving physical attachment that apes from other studies failed when tested with similar tasks using artificial as opposed to natural tools. We found no evidence that the orangutans' success in broken tool conditions was based on perceptual features unrelated to connectivity. Our results suggest that artificial tools may limit apes' knowledge of connectivity involving physical attachment, whereas ecologically valid tools may have the opposite effect.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Anthropology
Dewey Decimal Classification:300 Social sciences, sociology & anthropology
Language:English
Date:2013
Deposited On:22 Mar 2013 11:48
Last Modified:05 Apr 2016 16:35
Publisher:American Psychological Association
ISSN:0021-9940
Publisher DOI:https://doi.org/10.1037/a0028621

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