About the Authors

Kimberley J. Hockings

To whom correspondence should be addressed. E-mail: k.j.hockings@stir.ac.uk

Affiliation Department of Psychology, University of Stirling, Stirling, Scotland

Tatyana Humle

Affiliation Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America

James R. Anderson

Affiliation Department of Psychology, University of Stirling, Stirling, Scotland

Dora Biro

Affiliation Department of Zoology, University of Oxford, Oxford, United Kingdom

Claudia Sousa

Affiliation Department of Anthropology, New University of Lisbon, Lisbon, Portugal

Gaku Ohashi

Affiliation Primate Research Institute, Kyoto University, Kyoto, Japan

Tetsuro Matsuzawa

Affiliation Primate Research Institute, Kyoto University, Kyoto, Japan

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: JA KH. Performed the experiments: KH DB TH CS GO. Analyzed the data: KH. Contributed reagents/materials/analysis tools: TM KH. Wrote the paper: JA KH. Other: Editorial contributions: TM CS DB TH.