Abstract and Keywords
This chapter provides an introduction to the topic of Developmental Linguistics, which tries to understand children’s language acquisition in terms of the mental representations that support linguistic behavior. It offers an overview of the chapters in the volume: these examine specific linguistic domains, exploring the cognitive and linguistic supports for learning, patterns of development in children, and the links between cross-linguistic variation and children’s language development.
Modern linguistics asks three fundamental questions, articulated by Chomsky (1986): What exactly do you know when you know your native language? How did you come to know it? And, how do you put that knowledge to use? Investigation of the second question is the concern of developmental linguistics.
Leading research questions within developmental linguistics include the following: What do newborn children bring to the task of language acquisition in the form of prior knowledge, information processing capacity, and extralinguistic cognitive resources? What information must children extract from their linguistic input? How does biological maturation interact with the child’s developing linguistic abilities? What can the child’s process of language acquisition tell us about the nature of linguistic competence in an adult? How are children’s linguistic abilities informed by the study of extralinguistic cognition or by the information processing mechanisms that underlie on-line understanding?
Research findings in developmental linguistics are extremely difficult to interpret, for several reasons. First, as in all areas of linguistics, children’s performance reflects a combination of their grammatical knowledge with the production or comprehension mechanisms through which they produce behavior. Because children appear to be generally more susceptible to the contribution of performance factors than adults, it is difficult to know whether to assign credit or blame to the grammar or to the performance systems in any single case. Similarly, because so little is understood about speech production processes, even in adults, children’s utterances may be susceptible to interference from these factors. Of course, examining children’s behavior through a psycholinguistic lens may help to alleviate the credit-assignment problem. Some of this difficulty is also lessened when children are compared against explicit models of the acquired knowledge and of the range and limits of cross-linguistic variation. A concrete model of linguistic knowledge can often provide specific predictions that help to more accurately identify the contribution of grammatical knowledge.
The chapters in this handbook aim to use the relation between developmental findings and the core generalizations that any linguistic theory must account for as a guiding (p. 2) principle. Where linguistic theory provides constraints on possible grammars, these inform our analyses of children’s linguistic development. As a whole, the book also aims to explore the role of experience in shaping children’s linguistic development. How does the structure of the learner interact with features of the environment to drive learning?
The book is divided into 6 parts. Parts I–IV, which make up the bulk of the book, address key developmental findings in the core linguistic domains of phonology, morphology, syntax, and semantics/pragmatics. These chapters are fundamentally empirical in scope, while also tying the empirical and developmental phenomena to key insights in linguistic theory and to questions of learnability. Part V addresses computational approaches to learning, providing the state of the art in statistical and knowledge driven approaches to learning. Finally, Part VI addresses learning in atypical populations.
In Parts I–IV, each chapter addresses a single area of grammatical knowledge, such as syllable structure, negation, or binding theory. Authors were asked to address three fundamental issues. First, what is the current state of our understanding about the core linguistic generalizations in the domain under investigation. Second, what is the current state of our understanding of children’s development with respect to the phenomena under discussion. Third, given what we know about these generalizations and the nature of the linguistic environment, how might a learner deduce the correct grammatical structure in a given language?
We asked each author to provide an overview of the fundamental generalizations that guide current linguistic analyses and the features of grammatical representation that these generalizations entail. Within that area of grammar, the chapters ask what characteristics are plausibly shared by all human languages, and what characteristics are known to vary? Universals might (or might not) reflect innate characteristics of the human brain, but where grammars vary, the child necessarily deduces the correct option for her target language through analysis of her linguistic input.
Next, each author was asked to review the relevant acquisition literature. Each literature review aims to organize the principal findings according to target language, age range of the child, and research methodology (such as naturalistic observation, elicited production, or truth value judgment). This systematic approach automatically highlights any differences in findings according to research method. It also brings to light any informational gaps in the literature, such as lack of naturalistic data from children in a particular age range, for example, or lack of evidence concerning a theoretically central class of target languages.
Finally, authors were asked to raise considerations of language learnability. Given what we know about the nature of the child’s input, how in principle might a child deduce the correct grammatical options for her target language? To what extent do explicit representational theories make the input more or less informative? To what extent are such representational presuppositions necessary to garner learning benefits from the input? Do the experimental findings favor a particular approach to the logical problem of language acquisition? In what ways, if any, does the child’s knowledge surpass the information directly available from the input? In what ways can innate structure make the input (p. 3) more informative? Likewise, are there ways in which the child’s knowledge seems more limited than expected, given the richness of the available input?
These questions have particular interest for the developmental linguist, because they bear directly on the prior knowledge that the newborn child does (and does not) bring to the task of language acquisition, and on the child’s computational capacities and limitations at different stages of development.
Of course, for different phenomena, the relative proportion of linguistic, developmental, and learning theoretic knowledge varies. Consequently, the chapters vary in the degree to which each of these is emphasized. Readers of individual chapters, however, should be able to take away the current state of our understanding in a particular linguistic domain. And readers of the entire book will see the full range issues addressed in considerable depth across the chapters.
In Part V, the emphasis shifts away from particular grammatical phenomena and towards theories of learning. These chapters address the space of possible grammars and the learner’s ability to traverse that space from a computational perspective. In these chapters, readers will be able to learn about the key findings and methods in learnability theory, statistical inference, parameter setting, and constraint ranking. These chapters help to place the more phenomenologically grounded chapters of Parts I–IV in a broader perspective and point to tools that researchers can use to investigate the link between observations of development and theories of acquisition.
Part VI turns to language acquisition in atypical populations, asking how these populations help us to better understand the language faculty in the typical context. These chapters examine phonological and syntactic disorders and place them in a richly genetic and developmental linguistic context.
We hope that the book as a whole will guide future research in several ways. First, it will provide a comprehensive survey that can provide the basis for subsequent research. The comprehensive reviews found here will be a valuable first stop for researchers looking to begin their exploration of a new area. Second, by identifying gaps in our knowledge, the chapters provide obvious jumping-off points for future research. Third, by including discussion of typological variation and the role of input in acquisition, the chapters will lay the groundwork for future studies that examine how the learner interacts with the input in acquiring various features of the grammar. Finally, by bringing together, in a single volume, the work of scholars who study a diverse range of languages and developmental linguistic phenomena, we aim to provide a definitive statement of (a) the set of phenomena to which a theory of language development must be responsive, (b) the overarching learning-theoretic issues posed by the complexity of grammar acquisition, plus (c) a picture of the constraints on grammatical theory that are determined by our understanding of language acquisition. (p. 4)