School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, Belfast, UK.
Faculty of Biological Sciences, University of Leeds, Leeds, UK.
Sci Rep. 2019 Feb 14;9(1):2062. doi: 10.1038/s41598-019-38514-w.
Emotions are mental states occurring in response to external and internal stimuli and thus form an integral part of an animal's behaviour. Emotions can be mapped in two dimensions based on their arousal and valence. Whilst good indicators of arousal exist, clear indicators of emotional valence, particularly positive valence, are still rare. However, positively valenced emotions may play a crucial role in social interactions in many species and thus, an understanding of how emotional valence is expressed is needed. Vocalisations are a potential indicator of emotional valence as they can reflect the internal state of the caller. We experimentally manipulated valence, using positive and negative cognitive bias trials, to quantify changes in pig vocalisations. We found that grunts were shorter in positive trials than in negative trials. Interestingly, we did not find differences in the other measured acoustic parameters between the positive and negative contexts as reported in previous studies. These differences in results suggest that acoustic parameters may differ in their sensitivity as indicators of emotial valence. However, it is important to understand how similar contexts are, in terms of their valence, to be able to fully understand how and when acoustic parameters reflect emotional states.
情绪是动物行为中对外部和内部刺激做出反应的心理状态，是其不可或缺的一部分。情绪可以根据其唤醒度和效价在两个维度上进行映射。虽然有很好的唤醒度指标，但明确的情绪效价指标，特别是正效价，仍然很少。然而，在许多物种的社会互动中，积极的情绪可能起着至关重要的作用，因此，需要了解情绪效价是如何表达的。发声可能是情绪效价的一个潜在指标，因为它们可以反映发声者的内部状态。我们通过使用积极和消极的认知偏差试验来操纵效价，以量化猪叫声的变化。我们发现，在积极试验中，呼噜声比在消极试验中更短。有趣的是，与之前的研究报告不同，我们在积极和消极语境之间没有发现其他测量到的声学参数之间存在差异。这些结果的差异表明，声学参数在作为情绪效价指标的敏感性方面可能存在差异。然而，了解类似语境在效价方面的相似性非常重要，以便能够充分了解声学参数何时以及如何反映情绪状态。
