title: Nasal temperature drop in response to a playback of conspecific fights in chimpanzees: A thermo-imaging study.
abstract: Emotion is one of the central topics in animal studies and is likely to attract attention substantially in the coming years. Recent studies have developed a thermo-imaging technique to measure the facial skin temperature in the studies of emotion in humans and macaques. Here we established the procedures and techniques needed to apply the same technique to great apes. We conducted two experiments respectively in the two established research facilities in Germany and Japan. Total twelve chimpanzees were tested in three conditions in which they were presented respectively with the playback sounds (Exp. 1) or the videos (Exp. 2) of fighting conspecifics, control sounds/videos (allospecific display call: Exp. 1; resting conspecifics: Exp. 2), and no sound/image. Behavioral, hormonal (salivary cortisol) and heart-rate responses were simultaneously recorded. The nasal temperature of chimpanzees linearly dropped up to 1.5 °C in 2 min, and recovered to the baseline in 2 min, in the experimental but not control conditions. We found the related changes in excitement behavior and heart-rate variability, but not in salivary cortisol, indicating that overall responses were involved with the activities of sympathetic nervous system but not with the measureable activities of the hypothalamus-pituitary-adrenal (HPA) axis. The influence of general activity (walking, eating) was not negligible but controllable in experiments. We propose several techniques to control those confounding factors. Overall, thermo-imaging is a promising technique that should be added to the traditional physiological and behavioral measures in primatology and comparative psychology.
authors.affiliation: Kumamoto Sanctuary, Wildlife Research Center, Kyoto University, Kumamoto, Uki, Japan; Primate Research Institute, Kyoto University, Inuyama, Japan; Wildlife Research Center, Kyoto University, Kyoto, Japan; Department of Developmental and Comparative Psychology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Japan Society for Promotion of Science, Tokyo, Japan. Electronic address: fkanou@gmail.com.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Kano
authors.affiliation: Kumamoto Sanctuary, Wildlife Research Center, Kyoto University, Kumamoto, Uki, Japan; Wildlife Research Center, Kyoto University, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirata
authors.affiliation: Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Deschner
authors.affiliation: Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Behringer
authors.affiliation: Department of Developmental and Comparative Psychology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany; School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK.
authors.forename: Josep
authors.initials: J
authors.lastname: Call
mesh_terms: D000161:Acoustic Stimulation; D000374:Aggression / Q000502:physiology / Q000523:psychology; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods; D009039:Motion Perception / Q000502:physiology*; D009483:Neuropsychological Tests; D009666:Nose / Q000502:physiology*; D002679:Pan troglodytes / Q000502:physiology* / Q000523:psychology; D010775:Photic Stimulation; D012463:Saliva / Q000378:metabolism; D012938:Social Perception; D013817:Thermography / Q000379:methods
chemical_list: D006854:Hydrocortisone
keywords: Aggression; Emotion; Great ape; Skin temperature; Thermo-imaging