Twin Study of Language Development

描述（由申请人提供）：将进行一项双胞胎研究，以调查语言发展研究中两个长期存在的问题：(1)经验（相对于先天知识）起多大作用？(2)语言是否需要两种不同的心理计算：规则和联想？双胞胎方法是一种行为遗传学技术，它使用同卵和异卵双胞胎来估计遗传和环境对性状变异的相对贡献，可以帮助解决这些问题。虽然双胞胎方法已被应用于心理学的许多领域，但它在语言发展方面的潜力尚未得到充分利用。第一个问题是通过研究被动语态的发展来解决的，被动语态是儿童直到很晚（4-7岁）才掌握的结构。双胞胎方法用于确定遗传变异和环境变异（即语言输入的差异）在多大程度上分别对延迟负责。第二个问题是通过研究规则和不规则过去时的发展，以及其他类似的形态对比，作为规则与关联的例子来解决的。使用孪生方法来指定每种类型的结构（基于规则的结构和基于关联的结构）的发展遗传度，然后比较遗传度。实质性的差异将进一步支持这样一种观点，即成年人以不同的方式学习和完成这些过程。

DESCRIPTION (provided by applicant): A twin study will be carried out to investigate two long-standing questions in the study of language development: (1) How large a role does experience (as opposed to innate knowledge) play? and (2) Does language require two distinct kinds of mental computations: rules and associations? The twin method, a behavior genetic technique that uses identical and fraternal twins to estimate the relative contributions of heredity and environment to variation in a trait, can help to resolve these issues. While the twin method has been applied in many areas of psychology, it has not yet been used to its potential in language development. The first question is addressed by studying the development of the passive voice, a construction that is not mastered by children until quite late (age 4-7). The twin method is used to determine to what extent genetic variance and environmental variance (i.e., differences in language input) are each responsible for the delay. The second question is addressed by studying the development of regular and irregular past tenses, along with other, similar morphological contrasts, as example cases of rules versus associations. The twin method is used to specify the heritability of development of each of these types of constructions (rule-based ones versus association-based ones), and then the heritabilities are compared. A substantial difference would provide further support for the notion that these processes are learned in different ways and accomplished in different ways by adults.