Table of Contents
2. Critical Period Hypothesis
2.1 Age and First Language Acquisition
2.2 Age and Second Language Acquisition
3.1 Younger learners are the more successful learners
3.2 Older learners are the more successful learners
3.3 Younger learners are better in some respects
3.4 Younger learners are better in the long run
4. Learner Characteristics: Younger Learners vs. Older Learners
6. Early Second Language Learning
8. LIST OF REFERENCES
This term paper will focus on the discussion on the putative maturational constraints for second language acquisition. The age factor is an aspect of first and second language acquisition research which has engendered very much controversy. In the discussion about age-related effects on language acquisition, one can find disagreements as to both the facts and to their possible explanations. The different points of view range from the notion that young learners are in all aspects of language learning more efficient and achieve better results, to the contrary position that older learners are the better learners. In this paper, four of the positions concerning the age factor, which have been listed by Singleton, will be presented because they provide a good overview of the different views on this topic and the respective evidence belonging to them. Many of the differences in the results of various studies are due to the differences in how the results are elicited. The experimental design plays an important role for the outcomes.
It was long the prevalent opinion in public as well as research that younger learners learn better than older ones and this hypothesis is often used as supporting reason for the early introduction of foreign language teaching. The Critical Period Hypothesis supports this view theoretically. It is often explained by saying that the brain loses its plasticity from a particular age on and thereby loses also the ability to learn a new language as easily as it would have been possible previously. However, counter-evidence is available if one looks at adult learners who achieved to become successful in a language despite they started learning it after this putative time frame.
After explaining the Critical Period Hypothesis and the different positions concerning the age factor, there will be a general look at the characteristics of younger and older learners. Due to the fact that the distinctive types of input older and younger learners are exposed to is often seen as a cause for the different levels of attainment, this issue will be addressed in section five. Finally, there will be a link to the practical implications of the age factor-discussion by depicting the topic of early foreign language instruction.
2. Critical Period Hypothesis
Critical Period is the term used in biology to refer to a limited phase in the development of an organism during which a particular activity or competence must be acquired if it is to be incorporated into the behaviour of that organism. (Singleton 1989: 38)
The Critical Period Hypothesis (CPH) for language learning was formulated in the 1960s and stated that a human being has to acquire language within a specific time frame. Otherwise, i.e. if this period is missed, one cannot learn the language native-like. Scholars who agree about the existence of the CPH do, however, often disagree about its scope, timing and reasons for its existence.(cf. Long 2007: 44) The CP was seen as the time span during which the lateralization in the brain takes place, i.e. the functional specialisation of both hemispheres. (cf. Apeltauer 1997: 19) The stronger version of this hypothesis holds that language acquisition cannot start before the onset of this period and if it is missed, language acquisition cannot happen. The weaker version states that it is effective for language development if the acquisition process begins very early after the onset of the period and that beyond it the learning potential slowly declines, but never disappears completely. (cf. Singleton 1989: 38) This version has some similarities with the ‘Sensitive Period’ Hypothesis. The difference between this and the CPH is that the former argues that within the set period, language is easier to learn, i.e. the ‘Sensitive Period’ is the preferable period. In contrast to that the CPH states that the period demonstrates a cut-off point after which a successful language acquisition is no longer possible.
The neurolinguistic explanation for the CPH, e.g. Penfield’s notion that language learning beyond the end of the first decade of life is ‘unphysiological’ due to the decreasing cerebral plasticity, is not justified because, for instance, there are several examples of adults learning a L2 and achieving highly successful levels. The same applies to the explanation of Lenneberg who thought of the CPH as being linked to the lateralization of language functions in the brain – a notion that is undermined by later neurological evidence showing that lateralization takes place much earlier than puberty and that it is never absolute. (cf. Oksaar 2003, Singleton 1989: 229)
There are several notions about the causes of the CP. The neurological explanations of plasticity (Penfield, Roberts), lateralization (Lenneberg) and the localisation of specific language subfunctions in the brain (Seliger) are one area of reasons for the CPH. Other explanations can be found in cognitive factors; with DeKeyser as one advocate who claims that there is an “inescapable decline in language acquiring capacity because of cognitive maturation. He suggests […] a diminishing capacity for the implicit learning of complex abstract systems – including language”. (Singleton 2007: 51) Krashen on the other hand refers to affective-motivational factors as explanations for the CP and claims that the ‘affective filter’ is strengthened from the onset of puberty due to the onset of formal operations. (cf. ibd.) There are also those explanations that focus on sensory acuity or the differential factors in the input received by older and younger learners (section 5 ‘Input’).
Initially, the research focused predominantly on the acquisition of native-like accent, but in recent years it covered also other aspects of language competence like morpho-syntax or lexis, and thus there emerged those approaches which predicted multiple critical or sensitive periods, stating the possibility that different spheres of language competence go through different periods. The phonetic/phonological competences are predicted to come to an end very early whereas the time frames for morpho-syntax or pragmatics is thought to end later in life. Seliger, Diller or Scovel are advocates of this notion and have different explanations for it. Seliger (1978) for example argues that there is not only lateralization taking place in the brain, but also a localization process happens within the dominant hemisphere, suggesting that “phonetic/phonological functions are localized by puberty and that syntactic functions are localized subsequently, thus remaining acquirable until later in life.” (Singleton 2007: 49, cf. Johnstone 2002: 7) Seliger claims that the ability to achieve a native accent in a foreign language is lost first and represents the first CP.
Today, there is still the debate about the age factor, especially concerning its existence and scope in L2 acquisition, the most prevalent notion being that older learners are initially better, but the younger ones are better in the long run. (cf. Long 2007: 46-47)
2.1 Age and First Language Acquisition
There are various points of view regarding the possible onset of the Critical Period. Lenneberg (1967) claims, with reference to his studies with deaf children, that the starting point of the CP is around the second year of life. There is, however an amount of evidence against the assumption that the language acquisition tool does not work until the age of two. Children seem to acquire language from the day of their birth. Even the early sounds a child produces can be seen as the first linguistic utterances. Indeed, most of the articulatory features of language production can be found in infants’ early sounds. It can be suggested that there is no phase in a child’s development in which language is not being acquired. The acquisition of prosody seems to begin very early. It normally begins in the first six months of life and thus it can be claimed that all the basic elements of prosody are already in place well before the age of two at which Lenneberg sets the onset of language acquisition. The development of segmental and prosodic phonology as well as the interactive perspective serves as indicators for the notion that Lenneberg’s contention is unjustified. There seems to be no evidence for believing that there is a level of ‘physical maturation’ in the early human development where language acquisition suddenly starts and where a Critical Period for successful language acquisition begins. (cf. Singleton 1989: 41-44) To sum up, one can say that language acquisition is a continuous process which begins at birth.
The end of the CP has raised many questions and assumptions. The question to be asked is if it is possible for adults who have not acquired their first language (L1) within the Critical Period, to acquire it after this time frame. The age most often claimed to be the upper limit of the CP is the onset of puberty. Experiments to test this claim are not possible in L1 acquisition since one would have to deprive a child of linguistic interaction before puberty to prove it. However, there is evidence available, for example in the case of ‘Genie’ or the so-called ‘wolf-children’, i.e. children who grew up in isolation from human society. Instances where these children were just exposed to human language after puberty seem to be helpful, but they often lack particular information. The case of Victor, the ‘wild boy of Aveyron’, who came to public attention in the 18th century shows that he, despite he was reported to be healthy, was not able to acquire more than a few rudiments of language after he was trained. Victor reached puberty shortly after his language training programme began. However, this case could, comparable to the case of ‘Genie‘, be also related to other impairments, for example Victor’s nervous system was reported to have been affected in some way since he underwent spasms occasionally. Furthermore, the lack of interaction could have had an effect on him and he might also be mentally retarded. These other factors apart from the age factor might have affected his lack of ability to acquire language successfully as well. (cf. Singleton 1989: 45-47)
In conclusion, as Singleton remarked, it is probably not possible to find a definite upper age level after which language acquisition fails. Today there is the general assumption that L1 acquisition, at least some aspects of it, continues into adulthood and it is not verified by research that with increasing age there is necessarily a decline in intellectual or learning capacity. (cf. ibd.: 78)
2.2 Age and Second Language Acquisition
The critical question is whether there is indeed evidence for an optimal age in L2 acquisition and whether there are really age-related differences between younger and older learners. This question is not only of relevance for science but has also practical implications. Teachers and those responsible for educational policy are interested in knowing if there is an advisable time to start L2 instruction and how far older learners can be expected to progress in the L2. The CPH holds that young children learn a L2 especially effectively within a certain age frame because then their brains are still able to use the mechanisms which assisted their L1 acquisition. It further states that older learners acquire a language differently after a certain age and that after this phase the learners are unable to achieve a native-like competence in the target language, especially when it comes to accent. While some empirical studies are supportive to the CPH, others offer counter-evidence which shows that there is no cut-off point for language learning. Notably those studies which show native-like achievements of adult learners are used as evidence against the CPH. (cf. Cameron 2002: 42ff)
The thesis that children can easier learn the language in their environment through imitation than adults was seemingly supported by results from the neurological sciences, especially those of Penfield, Roberts and Lenneberg. They reasoned that the human brain would dispose from birth until puberty of a decreasing plasticity and that the functions which are processed in the adult brain in the left hemisphere can be taken over in younger learners’ brains by the right hemisphere. As the right hemisphere was associated with the global perception and holistic learning, the thesis was that until puberty a language could be learned more imitative – and imitation was thought by these scholars to be the condition for native-like proficiency in a second language. Therefore they concluded that successful L2 attainment can only be possible until the onset of puberty. However, today this assumption is undermined by several research activities showing that imitation is not the only condition for language learning. Lateralization and plasticity of the brain cannot be deemed as satisfying arguments because language processing takes place in both sides of the brain and until today it is not even sure when the process of lateralization begins and if there is not even a genetic anchorage. (cf. Kuhberg 2001: 702, Rück 1998) Factors such as language proficiency, length of language exposure, developmental stage, sex and number of languages the person is able to speak, seem to have an influence on the way the lateralization develops in human beings. Bilinguals show a speech processing on both sides of the brain whereas monolinguals process the language input predominantly in the left hemisphere. (cf. Kuhberg 2001: 703)
Higher evidence than those for the imitation or plasticity argument can be found in explanations of the age factor in L2 acquisition which argue from the sociological and pedagogical point of view. For example the fact that the socialisation of primary school pupils has not yet been completed is seen as an advantage to familiarise them with other thought-patterns, values and norms than those they encounter in their own cultural environment. The desired openness to other cultures would thus correlate with the social openness of the young children. (cf. Rück 1998: 30ff)
There is one version of the CPH which holds that those who acquire a L2 after puberty have only those principles and strategies available to them which were important for their L1 acquisition. This would mean that adult Japanese learners of English would not be able to acquire the English parameter of head-fist because their mother-tongue Japanese is a head-last language. Yet, there is evidence that adult Japanese learners learn the head-first parameter relatively fast and easy when acquiring English as their L2. So the lack of one particular parameter in the L1 does not preclude its later acquisition in L2 development after puberty. (cf. Singleton 1989: 92)
In general, the discussion about the Critical Period Hypothesis in L2 acquisition research revolves around 4 different positions. Three of them support the view that language acquisition is easier for younger learners whereas one position argues that older learners have advantages in the language acquisition process. In the following, all four positions, as well as some of the studies to support or rebut them, will be presented. (cf. ibd. 80)
3.1 Younger learners are the more successful learners
The following position derives directly from the conception of the Critical Period in L1 acquisition research. The supporters of this position argue that younger L2 learners are generally the more successful learners. In most versions it is claimed that puberty is the point from which on the language learning capacity declines. This position is also the favoured one in public belief.
One area of evidence for this first position concerning the CPH are the American studies of programmes of foreign languages in elementary schools. However, these studies were criticised because of the experimental design which did not take into account other variables – for example the compared groups differed in length of exposure. (cf. Singleton 1989: 80-82)
A second kind of evidence is the study of Asher&Garcia (1969) which illustrated ‘age of arrival’ (AOA) as the best predictor for a successful acquisition of a native-like pronunciation. The accents of 71 Cuban immigrants to the United States was judged by native speakers of English, in this case 19 high-school students. The immigrants, as well as a control group of native speakers were recorded when uttering the same set of English sentences. Asher&Garcia found that none of the Cuban immigrants was rated as native-like in terms of pronunciation. However, those who had entered the United States at a young age had the highest ratings, especially those with an AOA of 1 to 6 years. Consequently, it was found out that the younger a child was when it entered the foreign language environment, the higher were the chances to acquire a native-like accent. This probability increased with longer times of exposure to the L2. (cf. Singleton 1989: 83ff)
In a self-assessment study with English and Hebrew immigrants, Selger et al. (1975) found evidence for the notion ‘younger = better’ as well. English immigrants to Israel and Hebrew immigrants to the United States were asked to evaluate themselves. The question was, if they thought to have achieved a native-like accent. Those who had migrated before the age of nine reported to be often mistaken for a native speaker whereas most respondents who had migrated after the age of 16 felt that they still had a foreign accent. Yet, this kind of data should be evaluated cautiously since the interviews are not to be considered as ‘objective’ assessments. (cf. Singleton 1989: 85)