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.

Invited review: The evolution of cattle bioacoustics and application for advanced dairy systems

“…There are consistencies in the vocal correlates of arousal within livestock species, mostly related to F0 parameters and these seem to be in accordance with changes in behavioural and physiological parameters (Briefer et al, 2015a and2015b). In pigs, arousal was linked with intensity and central F0 in calls (Linhart et al, 2015); in horses arousal was highly correlated with F0 max and F0 start values and energy quartiles (Briefer et al, 2015a) and further in goats, arousal was linked with F0 mean and F0 end values, as well as energy quartiles (Briefer et al, 2015b). It is thus hypothesised that F0 parameters would also increase due to increases in arousal in cattle.…”

“…Vocalisation patterns have specifically been linked to arousal and valence in pigs, goats and horses (Linhart et al, 2015;Briefer et al, 2015a and2015b;Leliveld et al, 2016) with numerous studies relating stress to features of pig vocalisations (Weary et al, 1998;Puppe et al, 2005;Düpjan et al, 2008). Contrarily there is limited research on the vocal correlates of emotion in cattle.…”

“…For instance, in pigs positive valence was associated with a reduced vocal rate and negative valence was associated with calls of a longer duration (Leliveld et al, 2016). In horses valence was correlated with duration and G0 (second fundamental frequency) (Briefer et al, 2015a), whereas in goats F0 range and frequency modulation (FM) extent decreased from negative to positive valence (Briefer et al, 2015b). Thus, the Green, Johnston and Clark specific acoustic parameters of valence in dairy cattle breeds need further exploration to rule out any species or breed effects.…”

Facial Indicators of Positive Emotions in Rats

“…Positive emotions have been identified as a critical marker for good animal welfare [1], thus investigating methods for recognizing both negative and positive emotional states in animals is essential. In animals, emotional states may be inferred from behaviour [3] including vocalisations [4,5], physiology [6], neurophysiology [7] or cognitive biases [8,9]. Moreover, different emotional states can be expressed through changes in facial expression, as previously shown in human and non-human primate studies [10–12].…”

Sensory Branding: A Pilot Study of the Effect of Sensory Value on Branding in Electronic Word of Mouth (eWOM)

“…Wu and Wang (2011) suggested consumption experience consists of hedonistic and utilitarian elements, but it is emotional appeal that elicits positive or negative emotions. This draws on Morillo's (1990, p. 173) reward effect theory, and a more recent study which defined the two main dimensions of emotion: emotional arousal (calm versus excited) and valence (positive versus negative) (Briefer, Maigrot, Mandel, Freymond, Bachmann, & Hillmann, 2015).…”