Age and the Rate of Foreign Language Learning

Carmen Muñoz, Carmen Muñoz

• Publisher: Multilingual Matters
• Year: 2006
• ISBN:
  9781847699770
• Topic: Languages & Linguistics
• Subtopic: Psycolinguistics
• Index: Languages & Linguistics

This book examines the various ways in which age affects the process and the product of foreign language learning in a school setting. It presents studies that cover a wide range of topics, from phonetics to learning strategies. It will be of interest to students and researchers working in SLA research, language planning and language teaching.

Chapter 1

The Effects of Age on Foreign Language Learning: The BAF Project

CARMEN MUÑOZ

The idea that there is a critical age for language learning that finishes before puberty was popularised by the Canadian brain surgeons W. Penfield and L. Roberts in their book Speech and Brain Mechanisms (1959). Penfield enthusiastically defended an early start for second language learning, basing his ideas on his studies on brain damage and his experience with his own children. According to Penfield, the time to begin schooling in second languages was between the ages of 4 and 10. Theoretical support came soon from E. Lenneberg who, in his Biological Foundations of Language (1967), noted that the rapid growth of nerve connections, which ceases at puberty, coincides with the child’s acquisition of language. Lenneberg supported his neurological account of the Critical Period Hypothesis (henceforth CPH) with evidence from aphasic patients, who showed a more rapid recovery if the damage had taken place before puberty, and with feral children, children who had suffered social isolation and had not learnt language before puberty. Their inability to learn language after that time, Lenneberg argued, constituted evidence that language acquisition was impossible after the critical period.

However, the extant evidence of language learning by feral children is so scarce that it cannot be used to provide strong support for either this or opposing views. The case of Genie, a girl who had lived in social isolation until the age of 13;7, proved that language acquisition was not impossible after puberty, though it seemed to be incomplete (see Curtiss, 1977). Linguistic evidence from the Genie case is still in need of clarification (Jones, 1995), and the regression she suffered after several traumatic events underlines the fact that the social and psychological circumstances of feral children cannot constitute valid evidence for a firm conclusion regarding the critical period for language acquisition. Likewise, the pathological kind of evidence provided by aphasic patients needs to be treated with caution. More relevant evidence has recently come from the field of the acquisition of sign language, which suggests that morphology and syntax may be affected by late acquisition in the case of deaf persons who are not exposed to their first language (sign language) until later childhood or adulthood (Newport, 1990).

From a theoretical point of view, the idea of a critical period sprang from an innatist conception of language, which the prevalence of Chomsky’s proposals in the field of linguistics in the second half of the 20th century strongly reinforced. A biologically determined period for language acquisition fitted perfectly well in a theory that concedes a crucial role to biology in human linguistic competence. Recently, however, the field of child language acquisition seems to be drifting away from formal linguistics proposals, disappointed by their failure to explain how human children become skilled users of a natural language. Tomasello (2003) argues that one of the reasons for this failure lies in the continuity hypothesis, which attempts to explain children’s language in terms of the structures and rules used to account for adult language. The best known theoretical alternatives to generative grammar at the moment, the connectionist accounts (e.g. Elman, 2001) and the construction-based (usage-based) accounts (see Tomasello, 2003), are both data based. In the latter perspective, one of the reasons underlying children’s observed advantage in second language acquisition may be the fact that they are more flexible learners than adults in skilled activities.

The CPH and Second Language Acquisition

The study of second language acquisition originated from the field of first language acquisition, and has since been fed by hypotheses and theories first developed in the parent field. Among these, the hypothesis of the existence of a critical period for (first and second) language acquisition soon motivated a wealth of empirical studies in the 1970s. The work of that decade was summarised in the following three generalisations:

(1) Adults proceed through early stages of syntactic and morphological development faster than children (where time and exposure are held constant).

(2) Older children acquire faster than younger children (again, in early stages of syntactic and morphological development where time and exposure are held constant).

(3) Acquirers who begin natural exposure to second language during childhood generally achieve higher second language proficiency than those beginning as adults. (Krashen et al., 1979/1982, reprint: 161)

These generalisations led Krashen et al. (1979) to make a very important distinction between ultimate attainment and rate. Older learners have a superior learning rate, particularly in the first stages of the acquisition of morphosyntactic aspects, while younger learners are slower at first, but eventually show a higher level of ultimate attainment. The latter was held to constitute evidence for the existence of a critical period, beyond which second language acquisition cannot reach native-like levels of proficiency.

Since then, a large number of studies have compared native-likeness among younger and older starters. The most robust evidence for the existence of maturational constraints in second language acquisition seemed to be provided by the study by Johnson and Newport (1989) of Korean and Chinese learners of English using grammaticality judgement tests (Long, 1990). Many other studies have also focused on the acquisition of second language (L2) morphosyntax (e.g. Coppieters, 1987; DeKeyser, 2000; Johnson &s Newport, 1991; Patkowski, 1980; Schachter, 1996).

However, agreement is far from complete. Johnson and Newport’s findings have been questioned on both methodological and empirical grounds (but see a recent confirmatory study in DeKeyser, 2000). Methodological criticisms can be found in Bialystok (1997), and Bialystok and Hakuta (1999). Replications of Johnson and Newport’s (1989) seminal study have cast some doubt on the neurobiologically-based explanation of the younger learners’ advantage. For example, replications have found evidence of native language effects (Birdsong & Molis, 2001; van Wuijtswinkel, 1994, cited in Kellerman, 1995) and of post-maturational age-related effects (Birdsong & Molis, 2001), which are held to constitute grounds for refutation of the CPH (Pulvermüller & Schumann, 1994).

Other studies have also found evidence of native-likeness among post-puberty starters, which appears to disprove the CPH in relation to L2 acquisition. Examples are, in the area of Universal Grammar principles, the work by Birdsong (1992; Birdsong & Molis, 2001), and White and Genesee (1996); in the areas of perceptual abilities, production skills and underlying linguistic competence, the report by Ioup et al. (1994); and in the area of pronunciation, Bongaerts et al. (1997), and Bongaerts (1999), among others.

On the other hand, evidence has accumulated that an early start does not always guarantee native-like achievement (see Harley & Wang, 1997). Hyltenstam and Abrahamsson (2000, 2003) claim that native-like proficiency in a second language is unattainable even for very early starters due to the strong influence that maturation has on second language outcomes. Further, these authors maintain that previous research has failed to find non-native features because they may be imperceptible except in detailed and systematic linguistic analyses, that is, the sort of analyses that should be undertaken with apparently exceptional late learners.

In sum, although an early starters’ long-term advantage (for ultimate attainment) is recognised, the CPH itself does not seem to have unanimous support at present (see Birdsong (1999) for a review of the two positions). On the other hand, late starters’ short-term advantage for learning rate was firmly established by Snow and Hoefnagel-Höhle’s findings (1978). These researchers conducted a large study in a natural setting involving close to 100 subjects, English learners of Dutch in The Netherlands, ranging in age from 3 years to adult. Subjects were tested three times (some four) for a period of approximately one year: 6 weeks, 4–5 months, and 9–10 months after the first exposure to Dutch. Results from the first testing time showed that the teenagers did better than the two younger groups, suggesting an older learners’ superior rate of learning. However, they also did better than the adult group in most measures, probably due, in the authors’ view, to motivational and environmental factors. With longer residence in The Netherlands, the teenagers’ advantage over the younger groups diminished, and by the third time the scores of the 6–7-year-old learners were approaching those of the 12–15-year-old learners. The older learners were observed to be especially good at syntactic and morphological rule acquisition, and also at metalinguistic ability and vocabulary. The authors noted that the non-conversational nature of the tasks used was clearly cognitively demanding and context-reduced, which may have favoured the older learners (1978: 1123). Differences were smaller and less persistent in listening comprehension and storytelling, and the older subjects were only better at pronunciation in the first test session. Interestingly, a 12–15-year-old native Dutch-speaking group did better on the morphology- and vocabulary-related tasks than a 6–7-year-old native-speaking group, supporting the interpretation that older L2 learners have a maturational advantage over younger L2 learners in academic tasks of this kind, in accordance with their superior cognitive development.

The issue of time, and not just the initial moment of learning (age of onset), has proved to be crucial in age-related studies. As seen above, in a naturalistic learning situation with unlimited exposure to the target language, the advantage of older learners begins to disappear after one year (Snow & Hoefnagel-Höhle, 1978). Snow (1983) points out that data for studies in which adults show superior results were collected during the first two years of residence or social immersion. This observation may be extended to younger and older children, since as Slavoff and Johnson’s (1995) study reported, no difference was found between a group of learners who arrived in the United States between the ages of 7–9 and a group whose age at arrival was between 10–12, after only three years of residence. This is why it has been suggested that a minimum of five years of residence (Snow, 1983) and, more recently, ten years (DeKeyser, 2000) may be necessary in CPH studies in order to ensure methodologically that it is ultimate attainment, and not rate, that is being measured.

Theoretical Explanations of the CPH

The theoretical explanations of the CPH are many and varied (see Singleton & Ryan, 2004, for a recent complete review), but the most influential proposals have been of two types: neurological and developmental-cognitive. Neurological explanations were popularised by Penfield (Penfield & Roberts, 1959), who appealed to the loss of brain plasticity with maturation, and by Lenneberg (1967), who elaborated a proposal based on the process of lateralisation of language functions in the left hemisphere (see for related proposals Diller, 1981; Molfese, 1977; and Seliger, 1978). Later, the reduction of plasticity in the language areas of the brain more or less until puberty has been seen as an effect of the process of myelination affecting neurons with maturation (Long, 1990; Pulvermüller & Schumann, 1994). More recently, attention has been paid to the spatial representation in the brain of early and late L2 acquisition (Abutalebi et al., 2001; Kim et al., 1997; Perani et al., 1998; Wattendorf et al., 2001). The available evidence now supports a dynamic view in which brain structure and organisation may be as much the consequence as the cause of L2 learning (Abutalebi et al., 2001; Perani & Abutalebi, 2005; Perani et al., 2003; Perani et al., 1998), a view shared by a number of cognitive psychologists (see Bialystok & Hakuta, 1999).

Maturational explanations have come from theorists working within a nativist framework, in which Lenneberg’s proposals have been fully compatible with Chomsky’s linguistic theories. One of these explanations is the Competition Hypothesis proposed by Felix (1985): although post-pubertal learners still have access to the innate acquisition system, this system competes with the more general problem-solving cognitive system which develops beyond the Piagetian stage of formal operations. In contrast, the Fundamental Difference Hypothesis, proposed by Bley-Vroman (1989), denies adults direct access to Universal Grammar. According to this hypothesis, the inborn mechanism that children have is no longer operative in adulthood and adults must rely on general problem-solving procedures instead. The lack of access to Universal Grammar explains the fact that second language acquisition is not as successful in adults as in children.

DeKeyser’s (2000) interpretation of the Fundamental Difference Hypothesis attempts to explain not just the young learners’ long-term superiority but also older learners’ short-term superiority. According to DeKeyser, ‘somewhere between the ages of 6–7 and 16–17, everybody loses the mental equipment required for the implicit induction of the abstract patterns underlying a human language’ (2000: 518). Hence, it is the younger learners’ use of implicit learning mechanisms that explains their advantage over older learners. This formulation agrees with Lenneberg’s characterisation of the critical period: ‘… 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’ (1967: 176, my emphasis). The superiority of implicit mechanisms explains the younger learners’ advantage in a natural setting: children do better in terms of ultimate attainment because many elements of language are hard to learn explicitly, especially for those adults who have limited verbal ability.

In contrast, older learners learn faster because their capacities for explicit learning let them take short cuts (De Keyser, 2003: 335), an ability that explains their advantage in the initial stages. That is, adult second language acquisition (SLA) is mainly explicit, and adults rely on analytical thinking to a...