Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzee

Yoshi-Taka Matsuda; Masako Myowa-Yamakoshi; Satoshi Hirata

doi:10.7287/peerj.preprints.2262v1

Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzee

Yoshi-Taka Matsuda ¹, Masako Myowa-Yamakoshi², Satoshi Hirata³

1 Center for Baby Science, Doshisha University, Kizugawa, Kyoto, Japan

2 Graduate School of Education, Kyoto University, Kyoto, Japan

3 Wildlife Research Center, Kyoto University, Kyoto, Kyoto, Japan

DOI: 10.7287/peerj.preprints.2262v1

Published: 2016-07-06
Accepted: 2016-07-06

Subject Areas: Animal Behavior, Evolutionary Studies
Keywords: Chimpanzee, Face perception, Novelty, Familiarity, Categorical perception, Preferential looking

Copyright: © 2016 Matsuda et al.
Licence: This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.

Cite this article: Matsuda Y, Myowa-Yamakoshi M, Hirata S. 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.2262v1

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.