Social and Statistical Mechanisms of Prelinguistic Vocal Development

婴儿如何学习发出他们语言的声音？婴儿的发声能力在出生后的第一年发生了巨大的变化。从最早的、不成熟的发音开始，婴儿进步很快，通常在12个月大的时候会说出他们的第一个单词。在这个过程中，他们开始产生类似语音的音节，并根据他们所处的语言环境的音系模式来组织音节序列。虽然第一年的发声成就得到了很好的描述，但人们对推动发声发展的变化机制知之甚少。然而，许多关于鸟类歌唱学习的研究以及研究者的初步研究表明，社会环境是丰富的结构和反馈的来源，可以指导早期的发声学习和发展。语言前婴儿可以利用社会反馈来创造新的、更高级的发声吗？研究人员假设，有两个过程对声乐学习产生了社会影响。在最初的6个月里，婴儿会学到他们的喋喋不休会可靠地影响成年人的行为。从这个早期学习开始，婴儿开始适应社会对他们发声的反应。在接下来的6个月里，婴儿利用照顾者对他们喋喋不休的偶然反应来引导他们的发声朝着他们语言的音系模式发展。获取支配多个示例之间关系的潜在模式的知识是一个称为统计学习的过程。为了研究这些发声学习的过程，照顾者对婴儿声音的反应的形式和时间将被操纵。首先，我们将在2到5个月大的婴儿身上研究它们之间的学习过程和照顾者的反应之间的联系。婴儿的信息处理能力和照顾者对喋喋不休的自然反应将被用来预测学习中的个体差异。其次，对9个月大婴儿的语音的统计特性和偶然性进行操纵，以评估它们对发声学习的影响。统计学习在语音感知和产生中的作用将被直接比较。最后，将确定两种学习机制(2至5个月的联想学习和9个月的统计学习)之间的关系。这些研究的结果将使研究者能够整合社会学习和言语感知的数据，构建一个新的声音发展理论框架。这些实验将受益于数字技术的新应用，这些技术允许在自然互动期间实时操纵照顾者的行为(通过无线耳机发出的指令)。同时，婴儿发声的变化将被记录和分析。这项拟议的研究对于教育父母为他们的婴儿提供最佳的学习环境具有广泛和基本的意义。理解社会引导学习在言语和语言中的作用可以用来帮助照顾者以促进发展的方式对婴儿的行为更加敏感。研究社会对语音发展的影响将有助于研究言语病理以及成功和无序的交际发展的过程。这项研究将为理解早期社会学习在沟通和语言缺陷中的作用提供一个框架，例如自闭症和唐氏综合症。通过阐明婴儿向照顾者学习的机制，这些发现将有助于为患有发育障碍的婴儿设计行为干预措施。

How do infants learn to produce the sounds of their language? The vocal abilities of infants change dramatically over the first year of life. Beginning with the earliest, immature vocalizations, infants make rapid progress, typically producing their first words by 12 months of age. Along the way, they begin to produce speech-like syllables and to structure sequences of syllables in accordance with the phonological patterns of their language environment. While the vocal achievements of the first year are well-described, not nearly as much is known about the mechanisms of change that drive vocal development. However, many studies of song learning in birds, as well as the investigators' preliminary studies, indicate that the social environment is a source of rich structure and feedback that can guide early vocal learning and development. Can prelinguistic infants use social feedback to create new, more developmentally advanced vocalizations? The investigators hypothesize that two processes enable social influences on vocal learning. During the first 6 months, infants learn that their babbling reliably affects adults' behavior. From this early learning, infants become attuned to social responses to their vocalizing. Over the next 6 months, infants use the contingent reactions of caregivers to their babbling to guide their vocalizations towards the phonological patterns of their language. Acquiring knowledge of underlying patterns that govern the relations among multiple examples is a process known as statistical learning. To investigate these processes of vocal learning, the form and timing of caregivers' reactions to their infants' sounds will be manipulated. First, the process of learning associations between babbling and caregivers' reactions will be investigated in 2- to 5-month-old infants. Infants' information-processing capacities and caregivers' natural responsiveness to babbling will be used to predict individual differences in learning. Second, the statistical properties and contingency of speech to 9-month-old infants will be manipulated to assess their effects on vocal learning. The role of statistical learning in speech perception and production will be directly compared. Finally, the relation between the two learning mechanisms (associative learning at 2 to 5 months and statistical learning at 9 months) will be determined. Findings from these studies will allow the investigators to construct a new theoretical framework for vocal development, integrating data from social learning and speech perception. The experiments will benefit from new applications of digital technologies that allow caregiver behavior to be manipulated in real-time (via instructions given over wireless headphones) during naturalistic interaction. At the same time, changes in infants' vocalizations will be recorded and analyzed. The proposed research has broad and fundamental implications for educating parents in providing optimal learning environments for their infants. An understanding of the role of socially guided learning in speech and language could be used to help caregivers to be more sensitive to infants' behavior in ways that would facilitate development. Investigating social influences on phonological development will contribute to the study of speech-language pathology and of processes underlying both successful and disordered communicative development. This research will provide a framework for understanding the role of early social learning in communication and language deficits such as those seen in autism and Down's syndrome. By elucidating mechanisms by which infants learn from caregivers, these findings will be useful in designing behavioral interventions for infants with developmental disorders.