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Supplemental Information

Supplementary materials, eye-tracking data and cumulative histogram of fixation duration

DOI: 10.7287/peerj.preprints.2262v1/supp-1

Raw data of eye tacking (Excel file)

Raw data of all participants (eight chimpanzees) and analyzed data for figures 1 and 2.

DOI: 10.7287/peerj.preprints.2262v1/supp-2

Familiar-face movie clip (example)

DOI: 10.7287/peerj.preprints.2262v1/supp-3

Novel-face movie clip (example)

DOI: 10.7287/peerj.preprints.2262v1/supp-4

Intermediate-face movie clip (example)

DOI: 10.7287/peerj.preprints.2262v1/supp-5

Additional Information

Competing Interests

The authors declare that they have no competing interests.

Author Contributions

Yoshi-Taka Matsuda conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables.

Masako Myowa-Yamakoshi conceived and designed the experiments, contributed reagents/materials/analysis tools, reviewed drafts of the paper.

Satoshi Hirata performed the experiments, contributed reagents/materials/analysis tools, reviewed drafts of the paper.

Animal Ethics

The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):

This research was conducted in accordance with the Guide for the Care and Use of Laboratory Animals of Hayashibara Biochemical Laboratories, Inc. and the Weatherall report, The use of non-human primates in research. The research protocol was approved by the Animal Welfare and Animal Care Committee of the Hayashibara Great Ape Research Institute (GARI-051101).

Data Deposition

The following information was supplied regarding data availability:

The raw data has been supplied as a supplementary file.


This work was supported by funding from Grants-in-Aid for Scientific Research (KAKENHI 23300103, 26245069 and 24000001 to SH; 24119005 and 24300103 to MM-Y). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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