Infants’ prelinguistic vocalizations reliably organize vocal turn-taking with social partners, creating opportunities for learning to produce the sound patterns of the ambient language. This social feedback loop supporting early vocal learning is well-documented, but its developmental origins have yet to be addressed. When do infants learn that their non-cry vocalizations influence others? To test developmental changes in infant vocal learning, we assessed the vocalizations of 2- and 5-month-old infants in a still-face interaction with an unfamiliar adult. During the still-face, infants who have learned the social efficacy of vocalizing increase their babbling rate. In addition, to assess the expectations for social responsiveness that infants build from their everyday experience, we recorded caregiver responsiveness to their infants’ vocalizations during unstructured play. During the still-face, only 5-month-old infants showed an increase in vocalizing (a vocal extinction burst) indicating that they had learned to expect adult responses to their vocalizations. Caregiver responsiveness predicted the magnitude of the vocal extinction burst for 5-month-olds. Because 5-month-olds show a vocal extinction burst with unfamiliar adults, they must have generalized the social efficacy of their vocalizations beyond their familiar caregiver. Caregiver responsiveness to infant vocalizations during unstructured play was similar for 2- and 5-month-olds. Infants thus learn the social efficacy of their vocalizations between 2 and 5 months of age. During this time, infants build associations between their own non-cry sounds and the reactions of adults, which allows learning of the instrumental value of vocalizing.

中文翻译：

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学习如何从社会反馈中学习：早期发声的起源

婴儿的前语言发声可靠地组织了与社会伙伴的声音转换，为学习产生环境语言的声音模式创造了机会。这种支持早期声乐学习的社会反馈循环有据可查，但其发展起源尚未得到解决。婴儿什么时候知道他们的非哭声会影响他人？为了测试婴儿发声学习的发展变化，我们评估了 2 个月和 5 个月大的婴儿在与不熟悉的成人进行静止面孔互动时的发声。在静止面孔期间，学会发声的社会效能的婴儿会增加他们的牙牙学语率。此外，为了评估婴儿从他们的日常经历中建立的对社会反应的期望，我们记录了看护者在非结构化游戏中对婴儿发声的反应。在静止面部期间，只有 5 个月大的婴儿表现出发声增加（声音消失爆发），表明他们已经学会期待成人对他们发声的反应。照顾者的反应能力预测了 5 个月大的声音消失爆发的幅度。由于 5 个月大的婴儿在面对不熟悉的成年人时会突然爆发性发声，因此他们一定已经将发声的社会效能推广到他们熟悉的照顾者之外。对于 2 个月大和 5 个月大的婴儿，看护者在非结构化游戏中对婴儿发声的反应相似。因此，婴儿在 2 到 5 个月大时就学会了他们发声的社会效能。在这段时间，