Tutorials in Bilingualism

Psycholinguistic Perspectives

Annette M.B. de Groot, Judith F. Kroll

• Publisher: Psychology Press
• Year: 2014
• ISBN:
  9781317779384
• Edition: 1
• Topic: Personal Development
• Subtopic: Writing & Presentation Skills

The past fifteen years have witnessed an increasing interest in the cognitive study of the bilingual. A major reason why psychologists, psycholinguists, applied linguists, neuropsychologists, and educators have pursued this topic at an accelerating pace presumably is the acknowledgment by increasingly large numbers of language researchers that the incidence of monolingualism in individual language users may be lower than that of bilingualism. This alleged numerical imbalance between monolinguals and bilinguals may be expected to become larger due to increasing international travel through, for instance, tourism and trade, to the growing use of international communication networks, and to the fact that in some parts of the world (i.e., Europe), the borders between countries are effectively disappearing. In addition to the growing awareness that bilinguals are very common and may even outnumber monolinguals, there is the dawning understanding that the bilingual mind is not simply the sum of the cognitive processes associated with each of the two monolingual modes, and that the two languages of bilingual may interact with one another in complicated ways. To gain a genuinely universal account of human cognition will therefore require a detailed understanding of language use by both pure monolinguals as well as bilinguals, unbalanced and balanced, and of the representations and processes involved. These two insights, that bilingualism is a common human condition and that it may influence cognition, were presumably instrumental in putting bilingualism on the agendas of many researchers of cognition and language in recent years. But other reasons may have played a role too: The study of bilingualism also provides a unique opportunity to study the relation between language and thought. A final reason for the growing interest in this area of research is the awareness that bilingualism may confer the benefit of broadening one's scope beyond the limits of one's own country and culture. This book serves as an excellent introduction to the important topics in the psycholinguistic study of bilingualism. The chapters represent a comprehensive and interrelated set of topics that form the core of contemporary research on the psycholinguistics of bilingualism. The issues raised within this perspective not only increase our understanding of the nature of language and thought in bilinguals but also of the basic nature of the mental architecture that supports the ability to use more than one language.

Part One
Second Language Acquisition

CHAPTER ONE
The Critical Period Hypothesis: Where Are We Now?

Birgit Harley
Wenxia Wang
Ontario Institute for Studies in Education

The idea that children have a special talent for languages that is rarely, if ever, available to older learners is one that has much popular support. Among second language researchers, however, the related hypothesis of a maturationally delimited critical period for language acquisition has been a constant source of controversy. Not everyone accepts the view that young children have an inborn advantage over older learners, and even among those who take this position, debate continues as to what the causes of this advantage are, what the relevant age limits are, what aspects of language development it applies to, and what sort of empirical data provide a crucial test of the critical period hypothesis. In this chapter, we review relevant research findings and consider various proposed explanations of age-related differences in (second) language acquisition. We argue that, despite a number of unresolved problems and even some apparent counterevidence, the critical period concept, as it has evolved, continues to have considerable heuristic value in investigating the language development of learners whose exposure to a new language begins at different ages.

The Critical Period Concept

The critical period concept is a cross-disciplinary one that has been applied to various aspects of behavioral development in both animals and humans (e.g., Bornstein, 1987; Colombo, 1982; Immelmann & Suomi, 1981; Oyama, 1979). It refers to a period of time during the life cycle when there is greater sensitivity to certain types of environmental stimuli than at other times (Colombo, 1982), or "a period of competence for specific exchanges with the environment, bounded on both sides by states of lesser responsiveness" (Oyama, 1979, p. 88). A classic example is filial imprinting in birds. Lorenz (1937), for example, found that during a limited period soon after hatching, greylag goslings become irreversibly attached to the first moving object they see, this moving object normally being the parent. If exposure was delayed beyond a critical period lasting only a few days, the filial attachment was weaker or failed to occur. Time-constrained sensitivity to environmental stimuli has since been documented in many other animal species and developmental domains, including the learning of birdsongs, the development of vision in kittens and monkeys, and the social behavior of various species of mammals (e.g., Bornstein, 1987). As Lenneberg (1967), one of the first to apply the critical period concept to human language development,¹ commented, "Many animal forms traverse periods of peculiar sensitivities, response-propensities, or learning potentials. Insofar as we have made such a claim for language acquisition, we have postulated nothing that would be extraordinary in the realm of animal behavior" (p. 175). At the time this statement was made, the idea that human language learning could be compared to animal instincts (cf. Chomsky, 1959; Pinker, 1994) was actually rather more radical than Lenneberg allowed.

Since the 1960s, the critical period label for such phenomena has fallen out of favor with some investigators, owing to connotations of excessive rigidity and developmental fixity linked to the early imprinting studies. In its place, the term sensitive period is now more often preferred as indicative of the typically more gradual and environmentally susceptible nature of behavioral development. With respect to imprinting phenomena, Oyama (1979) noted that "they may be quite gradual, variable, and open to environmental influences" and that "they are not necessarily irreversible or instantaneous" (p. 85). In her review of the sensitive period concept in developmental studies, Oyama observed that the terms sensitive and critical are still used interchange ably by some researchers. This is the practice that we adopt in this chapter on the grounds that both terms are still current in the language acquisition literature and that no clear distinction is made between them

In an analysis of the criteria for a critical period, Colombo (1982) outlined five aspects that provide useful reference points for examining the application of the concept to language acquisition and for identifying the locus of the contentious issues that have arisen. A critical period, according to Colombo, must have (a) an onset, (b) a terminus, (c) an intrinsic (maturational) component, (d) an extrinsic component in the shape of a stimulus to which the organism is sensitive, and (e) a system that is affected by stimulation during the critical period. A further relevant distinction, discussed by Immelmann and Suomi (1981) and by Bornstein (1987), is the one between ultimate and proximate causes of critical period phenomena. Ultimate causes have to do with the functions and benefits of the critical period, whereas proximate causes are concerned with the (possibly multiple) mechanisms that regulate the growth and decline of sensitivity. Debate in the language domain, as we shall see, has focused more on proximate causes than on the more speculative issue of ultimate causes, though some observations on the latter have also been made.

Lenneberg’s Critical Period Hypothesis

The critical period hypothesis proposed by Lenneberg (1967) provides the appropriate starting point for our analysis of the ongoing debate concerning age-related effects in language acquisition. In his oft-cited work entitled Biological Foundations of Language, Lenneberg was intent on making the case for a nativist view of language acquisition and on countering the then still prevalent behaviorist view that primary language development is dictated by environmental shaping or training. With his strong emphasis on the role of maturation in language acquisition and his related arguments for a time-bounded decline in language capacity, he set the stage for many empirical studies to follow. We begin by outlining his claims in relation to each of Colombo's five criteria and by identifying some key issues that emerge in relation to each of these.

The Onset

Lenneberg (1967) was most specific about the beginning and end of the proposed critical period for language acquisition. Citing the regular timing of speech milestones in early childhood across a wide variety of environmental conditions, he argued that the onset of language is marked by "a peculiar, language-specific maturational schedule" (p. 131) consisting of a gradual unfolding of capacities between the second and third years of life; he attributed lack of speech prior to that time mainly to cerebral immaturity rather than, for example, to the immature state of the vocal tract. In a number of more specific references to age 2 as the onset of language, Lenneberg appears to have had in mind the two-word stage in children's speech—in other words, initial evidence for the use of syntax (cf. Chomsky, 1965). An obvious issue that arises in this connection is whether the two-word stage in production constitutes the onset of language more broadly conceived.

The Terminus

As for the end of the critical period, Lenneberg (1967) placed it rather firmly at age 13, or puberty. This, he argued, is a time of rapid decline in language acquisition capabilities, coinciding with the completion of lateralization of language function to the dominant left cerebral hemisphere and associated with "a loss of adaptability and inability for reorganization in the brain" (p. 179). Whether puberty is indeed a "turning point" (p. 150) for language acquisition has become the main focus of subsequent debate. Because first language development (barring unfortunate circumstances) normally starts for all children in infancy, it is an issue that has been most readily investigated in the context of second language learning. The theoretical interest of the terminus issue is not the only motivation for this focus. A postpubertal decline in capacity for second language acquisition would be of obvious practical educational relevance, too.

In fact, as Johnson and Newport (1989) have since pointed out, Lenneberg's (1967) brief comments about second language acquisition leave some doubt as to what his predictions about older second language learners might be. On the one hand, he appeared to be arguing that second language learning outside the critical period is different and less natural than that occurring during the critical period. Thus, he claimed: "The incidence of 'language learning blocks' rapidly increases after puberty. Also automatic acquisition from mere exposure to a given language seems to disappear after this age, and foreign languages have to be taught and learned through a conscious and labored effort" (p. 176). As Johnson and Newport noted, this argument suggests a maturational state version of the critical period hypothesis, which predicts that children will be inherently better than adults at learning both a first and a second language. The next point that Lenneberg made focused on the fundamental similarity of first and second language learning. Adults can learn to communicate in a second language, he argued, because "the cerebral organization for language learning as such has taken place during childhood, and since natural languages tend to resemble one another in many fundamental respects, the matrix for language skills is present" (p. 176). These comments suggest an exercise version of the critical period hypothesis that Johnson and Newport (1989) elaborated as follows: "Early in life, humans have a superior capacity for acquiring languages. If the capacity is not exercised during this time, it will disappear or decline with maturation. If the capacity is exercised, however, further language learning abilities will remain intact throughout life" (p. 64). Based on this interpretation, the critical period hypothesis makes the same prediction with respect to a first language but a different one for second languages, namely, that adults will be at least as capable of learning a second language as children.

Whatever the empirical evidence for a critical period ending at puberty might be, Lenneberg's (1967) explanation for the close of the critical period at this stage was soon to be challenged by evidence indicating that cerebral lateralization for language is present much earlier in childhood, if not at birth (Kinsbourne, 1975; Kinsbourne & Hiscock, 1977; Krashen, 1973). Moreover, Whitaker, Bub, and Leventer (1981) argued that there were no known neurological correlates for a sudden decline in language ability at puberty. This opened the door to continuing debate about the relevant proximate cause(s) of the hypothesized decline in language capacity.

In summary, although Lenneberg's placement of the terminus for the critical period for primary language acquisition was unambiguously at puberty, the relevance of this turning point for learning a second language was not clearly spelled out. In addition, once his neural basis for the close of the critical period was called into question, the vacuum was filled with a great variety of new explanations for which solid empirical evidence is still generally lacking. Small wonder, then, that the terminus of Lenneberg's critical period has been a major source of contention.

The Intrinsic Component

An important aspect of Lenneberg's critical period hypothesis is the idea that the child is endowed from the outset with an "innate mechanism" (1967, p. 22) dedicated to language, determining not only the underlying form it will take but also the "peculiar language-specific maturational schedule" (p. 131) it will follow. This idea, considered to be a necessary aspect of any sensitive/critical period, bears an obvious resemblance to the current concept of modularity (Fodor, 1983) that entails a domain-specific language module, or cluster of modules, operating autonomously from more general cognitive processes and incorporating the principles and parameters of Universal Grammar (Chomsky, 1981). Whether the principles and parameters of Universal Grammar are still fully available to older second language learners is one way in which the critical period question has more recently been conceptualized

It should be emphasized that Lenneberg (1967) did not claim to have identified the intrinsic neural component—the innate mechanism—of the hypothesized critical period for language acquisition. He discussed various aspects of the physical maturation of the brain, but stressed that knowledge of the anatomical or biochemical basis of language development was, at the time, insufficient to make the search for a specific neural explanation worthwhile. Significantly, however, he argued that it is the way the many parts of the brain interact rather than specific brain structures that should be considered the proper neurological correlate of language. Based on advances in neurobiological research in the intervening years, proposals as to potential neural correlates of language acquisition have recently been made, providing a new forum for debate (e.g., Eubank & Gregg, 1995; Jacobs & Schumann, 1992; Pulvermüller & Schumann, 1994).

The Extrinsic Component

As far as the extrinsic stimulus for language acquisition is concerned, Lenneberg's (1967) purpose appears to have been to persuade others that this was less important than was generally believed. He was clearly not interested in elaborating on this aspect, although he recognized that environmental influences on language acquisition were undeniable. The lack of specification of this critical period criterion has since been pointed out as an obvious weakness in the hypothesis (Colombo, 1982). Interestingly, accor...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Contents
• Preface
• Introduction and Overview
• PART I SECOND LANGUAGE ACQUISITION
• PART II REPRESENTATION, COMPREHENSION, AND PRODUCTION IN TWO LANGUAGES
• PART III THE CONSEQUENCES OF BILINGUALISM FOR THOUGHT AND FOR SPECIAL FORMS OF LANGUAGE PROCESSING
• Author Index
• Subject Index