Emotional valence : Is it reflected in call types and in acoustic properties of piglet vocalizations?
Résumé
How emotional valence is encoded in mammalian vocalizations is a prominent question in animal-welfare-oriented bioacoustics. We assessed this question using 1513 calls produced by 84 piglets in 11 situations. The negativity of the situations was ranked based on judgments of 28 pig behaviour experts. The acoustic quality of calls was described with 8 acoustic parameters. K-means clustering method was used to classify the calls into 5 call types. Statistics were calculated based on situation means (N=11, P adjusted for multiple testing). More negative situations were associated with longer calls (rs=-0.80, P=0.025) but no other acoustic parameter was associated with the experts’ ranking of situations. The proportion of high-pitched, stable frequency “scream” calls was higher in more negative situations (b=-0.55, P=0.012) while medium-pitched tonal “croaking” calls were increasing in more positive situations (b=0.34, P=0.012). Thus the acoustic quality and the call types were related to the expert-ranked negativity of the situation but not as much as expected. The experts might have overrated negativity of some human-induced situations (eg, brief isolation) and underrated negativity pig-induced situations such a fighting for teats. Emotional valence is encoded in piglet vocalizations but animal-based measures of the situations’ negativity are needed to assess the relationship precisely.
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers produits par l'(les) auteur(s)