Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzee
A peer-reviewed article of this Preprint also exists.
Author and article information
Abstract
Highly social animals possess a well-developed ability to distinguish the faces of familiar from novel conspecifics to induce distinct behaviors for maintaining society. However, the behaviors of animals when they encounter ambiguous faces of familiar yet novel conspecifics, e.g., strangers with faces resembling known individuals, have not been well characterised. Using a morphing technique and preferential-looking paradigm, we address this question via the chimpanzee’s facial–recognition abilities. We presented eight subjects with three types of stimuli: (1) familiar faces, (2) novel faces and (3) intermediate morphed faces that were 50% familiar and 50% novel faces of conspecifics. We found that chimpanzees spent more time looking at novel faces and scanned novel faces more extensively than familiar or intermediate faces. Interestingly, chimpanzees looked at intermediate faces in a manner similar to familiar faces with regards to the fixation duration, fixation count, and saccade length for facial scanning, even though the participant was encountering the intermediate faces for the first time. We excluded the possibility that subjects merely detected and avoided traces of morphing in the intermediate faces. These findings suggest a bias for a feeling-of-familiarity that chimpanzees perceive familiarity with an intermediate face by detecting traces of a known individual, as 50% alternation is sufficient to perceive familiarity.
Cite this as
2016. Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzee. PeerJ Preprints 4:e2262v1 https://doi.org/10.7287/peerj.preprints.2262v1note This preprint is not peer-reviewed. You may wish to reference the subsequent peer-reviewed version of this article.
Author comment
This is a submission to PeerJ for review.
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Supplemental Information
Supplementary materials, eye-tracking data and cumulative histogram of fixation duration
Raw data of eye tacking (Excel file)
Raw data of all participants (eight chimpanzees) and analyzed data for figures 1 and 2.
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.
Funding
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.
