A competitive nonverbal false belief task for children and apes

Authors

  • Carla Krachun,

    1. Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
    2. Institute of Cognitive Science, Carleton University, Ottawa, Canada
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  • Malinda Carpenter,

    1. Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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  • Josep Call,

    1. Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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  • Michael Tomasello

    1. Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Address for correspondence: Carla Krachun, Institute of Cognitive Science, Carleton University, 1125 Colonel By Drive, Ottawa, Canada, K1S 5B6; e-mail: ckrachun@connect.carleton.ca or Malinda Carpenter, Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; e-mail: carpenter@eva.mpg.de

Abstract

A nonverbal false belief task was administered to children (mean age 5 years) and two great ape species: chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). Because apes typically perform poorly in cooperative contexts, our task was competitive. Two versions were run: in both, a human competitor witnessed an experimenter hide a reward in one of two containers. When the competitor then left the room (version A) or turned around (version B), the experimenter switched the locations of the containers. The competitor returned and reached with effort, but unsuccessfully, towards the incorrect container. Children displayed an understanding of the competitor's false belief by correctly choosing the other container to find the reward. Apes did not. However, in version A (but not version B), apes looked more often at the unchosen container in false belief trials than in true belief control trials, possibly indicating some implicit or uncertain understanding that needs to be investigated further.

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