Saito Yumi, Yuki Shoko, Seki Yoshimasa, Kagawa Hiroko, Okanoya Kazuo
Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo, Japan.
Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo, Japan; Okanoya Emotional Information Project, ERATO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan.
Behav Processes. 2016 Nov;132:5-11. doi: 10.1016/j.beproc.2016.08.005. Epub 2016 Aug 31.
Emotional contagion occurs when an individual acquires the emotional state of another via social cues, and is an important component of empathy. Empathic responses seen in rodents are often explained by emotional contagion. Rats emit 50kHz ultrasonic vocalizations (USVs) in positive contexts, and emit 22kHz USVs in negative contexts. We tested whether rats show positive or negative emotional contagion after hearing conspecific USVs via a cognitive bias task. We hypothesized that animals in positive emotional states would perceive an ambiguous cue as being good (optimistic bias) whereas animals in negative states would perceive the same cue as being bad (pessimistic bias). Rats were trained to respond differently to two sounds with distinct pitches, each of which signaled either a positive or a negative outcome. An ambiguous cue with a frequency falling between the two stimuli tested whether rats interpreted it as positive or negative. Results showed that rats responded to ambiguous cues as positive when they heard the 50kHz USV (positive vocalizations) and negative when they heard the 22kHz USV (negative vocalizations). This suggests that conspecific USVs can evoke emotional contagion, both for positive and negative emotions, to change the affective states in receivers.
当个体通过社会线索获得另一个体的情绪状态时，就会发生情绪感染，它是共情的一个重要组成部分。在啮齿动物中观察到的共情反应通常用情绪感染来解释。大鼠在积极情境中会发出50kHz的超声波发声（USV），在消极情境中会发出22kHz的USV。我们通过一项认知偏差任务测试了大鼠在听到同种个体的USV后是否会表现出积极或消极的情绪感染。我们假设处于积极情绪状态的动物会将一个模糊的线索视为好的（乐观偏差），而处于消极状态的动物会将相同的线索视为坏的（悲观偏差）。训练大鼠对两种不同音高的声音做出不同反应，每种声音分别表示积极或消极的结果。一个频率介于两种刺激之间的模糊线索测试大鼠是将其解释为积极还是消极。结果表明，当大鼠听到50kHz的USV（积极发声）时，它们会将模糊线索视为积极的；而当它们听到22kHz的USV（消极发声）时，会将其视为消极的。这表明同种个体的USV能够引发情绪感染，无论是积极情绪还是消极情绪，从而改变接受者的情感状态。
