Age, empathy, familiarity, domestication and call features enhance human perception of animal emotion expressions.

Vocalizations constitute an effective way to communicate both emotional arousal (bodily activation) and valence (negative/positive). There is strong evidence suggesting that the convergence of vocal expression of emotional arousal among animal species occurs, hence enabling cross-species perception of arousal, but it is not clear if the same is true for emotional valence. Here, we conducted a large online survey to test the ability of humans to perceive emotions in the contact calls of several wild and domestic ungulates produced in situations of known emotional arousal (previously validated using either heart rate or locomotion) and valence (validated based on the context of production and behavioural indicators of emotions).

Cross-species discrimination of vocal expression of emotional valence by Equidae and Suidae.

Background: Discrimination and perception of emotion expression regulate interactions between conspecifics and can lead to emotional contagion (state matching between producer and receiver) or to more complex forms of empathy (e.g., sympathetic concern).

Encoding of Emotional Valence in Wild Boar () Calls.

Measuring emotions in nonhuman mammals is challenging. As animals are not able to verbally report how they feel, we need to find reliable indicators to assess their emotional state. Emotions can be described using two key dimensions: valence (negative or positive) and arousal (bodily activation or excitation).

Erratum: Segregation of information about emotional arousal and valence in horse whinnies.

This corrects the article DOI: 10.1038/srep09989.

Vocal expression of emotional valence in Przewalski's horses (Equus przewalskii).

Vocal expression of emotions has been suggested to be conserved throughout evolution. However, since vocal indicators of emotions have never been compared between closely related species using similar methods, it remains unclear whether this is the case. Here, we investigated vocal indicators of emotional valence (negative versus positive) in Przewalski's horses, in order to find out if expression of valence is similar between species and notably among Equidae through a comparison with previous results obtained in domestic horse whinnies.

Perception of emotional valence in horse whinnies.

Background: Non-human animals often produce different types of vocalisations in negative and positive contexts (i.e. different valence), similar to humans, in which crying is associated with negative emotions and laughter is associated with positive ones.

Segregation of information about emotional arousal and valence in horse whinnies.

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.