Does a cichlid fish process face holistically? Evidence of the face inversion effect
Faces are the most important body part for differentiating among human individuals by humans. Humans read the face as a whole, rather than looking at its parts, which makes it more difficult to recognise inverted faces than upright. Some other mammals also identify each other based on the upright face and take longer to recognise inverted faces. This effect is called the face inversion effect and is considered as evidence for face-specific perception. This ability has rarely been observed in animals other than mammals, but it was recently reported that some fish species could distinguish among individuals based on the face. For example, the cichlid fish Neolamprologus pulcher rapidly recognises familiar conspecifics by faces rather than other body parts. Here, we examined the face inversion effect in N. pulcher, by showing photographs of conspecific fish faces and objects in both upright and inverted orientations. Subjects gazed at novel faces longer than familiar faces in upright presentation, whereas they did not show such a tendency for inverted faces. Although the object discrimination was difficult, we did not observe the difference between upright and inverted object photographs. Our results indicate that fish exhibits the inversion effect for faces. These findings suggest that N. pulcher may process their conspecifics’ face holistically, like humans.
KeywordsCichlid fish Face inversion effect Face perception Holistic processing Visual paired comparison
We thank the members of the Laboratory of Animal Sociology, Osaka City University, for their general assistance and fruitful discussion.
KK, TH, and MK conceived and designed the experiments. KK performed the experiments and analysed the data. KK, TH, and MK contributed reagents/materials/analysis tools. KK, TH, and MK wrote this paper.
This study was financially supported by Japan Society for the Promotion of Science (JSPS) Grants-in-aid of Scientific Research (KAKENHI) (Nos. 26540070, 26118511, 16H05773, and 17K18712) to MK and (No. H16J09486) to TH.
Compliance with ethical standards
Conflict of interest
Authors KK, TH, and MK declare that they have no conflict of interest.
Our experiment did not kill study fish. Fish were fed sufficient food once per day and kept in good aquarium conditions. Diseased or injured individuals were removed from the experimental aquarium, treated with medication, and used only after recovery. Our experiments were conducted in compliance with the Guidelines for Animal Welfare of the Japan Ethological Society, and the Animal Care and Use Committee of Osaka City University. No permits from Japanese government were needed for experiments involving N. pulcher.
- Brecht KF, Wagner L, Ostojic L, Clayton NS, Nieder A (2017) Comparing the face inversion effect in crows and humans. J Comp Psychol A 203(12):1017–1027Google Scholar
- Bruce V, Young A (1998) In the eye of the beholder: the science of face perception. Oxford University Press, OxfordGoogle Scholar
- Burke D, Sulikowski D (2013) The evolution of holistic processing of faces. Front Psychol 4. https://doi.org/10.3389/fpsyg.2013.00011
- Helfman G, Collete BB, Facey DE, Bowen BW (2009) The diversity of fish: biology, evolution and ecology. Wiley, HobokenGoogle Scholar
- Hotta T, Kawasaka K, Satoh S, Kohda M (2018) Fish focus primarily on the faces of other fish. Sci Rep (unpublished) Google Scholar
- Kohda M, Jordan LA, Hotta T, Kosaka N, Karino K, Tanaka H, Taniyama M, Tomohiro T (2015) Facial recognition in a group-living cichlid. PLoS One 10. https://doi.org/10.1371/journal.pone.0142552
- Peterson MA, Rhodes G (2003) Perception of faces, objects, and scences analystic and holistic processes. Oxford University Press, OxfordGoogle Scholar
- Satoh S, Tanaka H, Kohda M (2016) Facial recognition in a discus fish (Cichlidae): Experimental approach using digital models. PLoS One 11. https://doi.org/10.1371/journal.pone.0154543
- Tanaka JW, Farah MJ (2003) The holistic representation of faces. In: Peterson MA, Rhodes G (eds) Perception of faces, objects, and scenes: analytic and holistic processes. Oxford University Press, OxfordGoogle Scholar
- Yovel G, Kanwisher N (2004) Face perception: domain specific, not process specific. Neuron 44:889–898Google Scholar