The body inversion effect in chimpanzees (Pan troglodytes)

• Published in: PloS one Vol. 13; no. 10; p. e0204131
• Main Authors: Gao, Jie, Tomonaga, Masaki
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 03.10.2018; Public Library of Science (PLoS)
• Subjects: Analysis; Biology and Life Sciences; Body parts; Brain research; Chimpanzees; Contours; Genetic aspects; Human remains; Inversion; Inversion effects; Matching-to-sample; Medicine and Health Sciences; Monkeys & apes; Pan troglodytes; Physiological aspects; Primates; Psychological aspects; Recognition (Memory); Research and Analysis Methods; Social Sciences; Stimuli; Studies; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0204131

Bodies are important social cues for animals. Body recognition in humans is deteriorated by inversion. This inversion effect suggests the configural processing of bodies, which is different from the processing used for other objects. However, it is not known if this type of body processing exists in non-human primates. We tested seven chimpanzees using upright and inverted chimpanzee body stimuli and other stimuli in matching-to-sample tasks to examine the body inversion effect and the body parts that invoke it. Our results reflected the body inversion effect for intact chimpanzee bodies, bodies with complete body contours, and bodies with clear faces but not for the objects and other conditions that did not present complete body contours and clear faces. The results show that chimpanzees share configural body processing with humans and that bodies are special to them compared with other objects. The results also revealed the functions of faces and body contours in configural processing by chimpanzees.