PEGASE, INRAE, Institut Agro, 35590, Saint Gilles, France.
UMRH, INRAE, VétoAgroSup, Université Clermont Auvergne, 63122, St-Genès Champanelle, France.
Sci Rep. 2020 Oct 28;10(1):18496. doi: 10.1038/s41598-020-75378-x.
Emotions not only arise in reaction to an event but also while anticipating it, making this context a means of accessing the emotional value of events. Before now, anticipatory studies have rarely considered whether vocalisations carry information about emotional states. We studied both the grunts of piglets and their spatial behaviour as they anticipated two (pseudo)social events known to elicit positive emotions of different intensity: arrival of familiar conspecifics and arrival of a familiar human. Piglets spatially anticipated both pseudo-social contexts, and the spectro temporal features of grunts differed according to the emotional context. Piglets produced low-frequency grunts at a higher rate when anticipating conspecifics compared to anticipating a human. Spectral noise increased when piglets expected conspecifics, whereas the duration and frequency range increased when expecting a human. When the arrival of conspecifics was delayed, the grunt duration increased, whereas when the arrival of the human was delayed, the spectral parameters were comparable to those during isolation. This shows that vocal expressions in piglets during anticipation are specific to the expected reward. Vocal expressions-both their temporal and spectral features- are thus a good way to explore the emotional state of piglets during the anticipation of challenging events.
情绪不仅会在对事件做出反应时产生，也会在预期事件时产生，这使得这种情境成为获取事件情感价值的一种手段。在此之前，预期研究很少考虑发声是否携带有关情绪状态的信息。我们研究了小猪在预期两种（伪）社交事件时的呼噜声及其空间行为，这两种事件已知会引起不同强度的积极情绪：熟悉同类的到来和熟悉人类的到来。小猪在空间上预期了这两种伪社交情境，呼噜声的时频特征根据情绪情境而有所不同。与预期人类相比，小猪在预期同类时发出的低频呼噜声的频率更高。当小猪预期同类时，频谱噪声增加，而当预期人类时，持续时间和频率范围增加。当同类的到来被延迟时，呼噜声的持续时间增加，而当人类的到来被延迟时，频谱参数与隔离时相当。这表明，小猪在预期时的发声表达是针对预期奖励的。因此，发声表达——无论是其时间还是频谱特征——都是探索小猪在预期挑战性事件时情绪状态的一种很好的方式。
