Differences in the Nonverbal Requests of Great Apes and Human Infants

Authors


  • We thank Mireille Hassemer, Birgit Knudsen, Rocio Silva Zunino, Stefanie Voigt, and Johanna van Schaik for help with the data collection, and Loraen Kaltenschnee, Mireille Hassemer, and Lena Schumacher for help with the coding. Special thanks go to Johannes Grossmann from the Max-Planck-Institute for Evolutionary Anthropology for his essential support and assistance in data collection.

Abstract

This study investigated how great apes and human infants use imperative pointing to request objects. In a series of three experiments (infants, = 44; apes, = 12), subjects were given the opportunity to either point to a desired object from a distance or else to approach closer and request it proximally. The apes always approached close to the object, signaling their request through instrumental actions. In contrast, the infants quite often stayed at a distance, directing the experimenters' attention to the desired object through index-finger pointing, even when the object was in the open and they could obtain it by themselves. Findings distinguish 12-month-olds' imperative pointing from ontogenetic and phylogenetic earlier forms of ritualized reaching.

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