title: Segregation of information about emotional arousal and valence in horse whinnies.
abstract: Studying vocal correlates of emotions is important to provide a better understanding of the evolution of emotion expression through cross-species comparisons. Emotions are composed of two main dimensions: emotional arousal (calm versus excited) and valence (negative versus positive). These two dimensions could be encoded in different vocal parameters (segregation of information) or in the same parameters, inducing a trade-off between cues indicating emotional arousal and valence. We investigated these two hypotheses in horses. We placed horses in five situations eliciting several arousal levels and positive as well as negative valence. Physiological and behavioral measures collected during the tests suggested the presence of different underlying emotions. First, using detailed vocal analyses, we discovered that all whinnies contained two fundamental frequencies ("F0" and "G0"), which were not harmonically related, suggesting biphonation. Second, we found that F0 and the energy spectrum encoded arousal, while G0 and whinny duration encoded valence. Our results show that cues to emotional arousal and valence are segregated in different, relatively independent parameters of horse whinnies. Most of the emotion-related changes to vocalizations that we observed are similar to those observed in humans and other species, suggesting that vocal expression of emotions has been conserved throughout evolution.
authors.affiliation: ETH Zürich, Institute of Agricultural Sciences, Universitätstrasse 2, 8092, Zürich, Switzerland.
authors.forename: Elodie F
authors.initials: EF
authors.lastname: Briefer
authors.affiliation: ETH Zürich, Institute of Agricultural Sciences, Universitätstrasse 2, 8092, Zürich, Switzerland.|Agroscope - Swiss National Stud Farm, Les Longs Prés, P.O. Box 191, 1580, Avenches, Switzerland.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Maigrot
authors.affiliation: ETH Zürich, Institute of Agricultural Sciences, Universitätstrasse 2, 8092, Zürich, Switzerland.|Koret School of Veterinary Medicine, Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University, Rehovot, 76100, Israel.
authors.forename: Roi
authors.initials: R
authors.lastname: Mandel
authors.affiliation: Agroscope - Swiss National Stud Farm, Les Longs Prés, P.O. Box 191, 1580, Avenches, Switzerland.
authors.forename: Sabrina Briefer
authors.initials: SB
authors.lastname: Freymond
authors.affiliation: Agroscope - Swiss National Stud Farm, Les Longs Prés, P.O. Box 191, 1580, Avenches, Switzerland.
authors.forename: Iris
authors.initials: I
authors.lastname: Bachmann
authors.affiliation: ETH Zürich, Institute of Agricultural Sciences, Universitätstrasse 2, 8092, Zürich, Switzerland.
authors.forename: Edna
authors.initials: E
authors.lastname: Hillmann
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology*; D005075:Biological Evolution; D003463:Cues; D005059:Euphoria / Q000502:physiology*; D005260:Female; D005639:Frustration; D006736:Horses / Q000502:physiology*; D006801:Humans; D008297:Male; D013016:Sound; D014828:Vocalization, Animal / Q000502:physiology*