This case study in relation to the research conducted by linguists in second language acquisition, shows that there is no critical period for vocabulary, syntax and grammar, but that there is a critical period for phonological skills. This period is different among individuals, and is determined by several factors, such as motivation, repetition, encouragement, and shared phonological features between one’s first and second language.
The argument I am supporting in this article is that there is a critical period for second language acquisition, and that it applies only to accent. To support my argument, I will examine the case of J.M., a native Spanish speaker who learned English as a second language. In addition, I will examine whether the conclusions drawn from J.M.’s case are in agreement with some of the existing literature where viewpoints of linguists are presented.
J.M. started learning English at the age of eleven in Spain. His teachers gave great importance to syntax and grammar, and consequently J.M. was very competent in these areas. However, all of his teachers were non-native speakers of English and their accent was not native-like; as a result, J.M.’s English sound production was also non-native like. In the classroom, J.M. was never corrected when he pronounced a word incorrectly. J.M. was immersed into an English-speaking environment when he came to the United States at the age of 18. This age is quite beyond the critical age, which ends at puberty, according to Lenneberg (1967, cited in Grimshaw et al., 1998).
I will examine whether and how J.M.’s accent, vocabulary, grammar and syntax evolved after his arrival in the United States, and will investigate whether these results agree with the existing literature. First, let’s examine vocabulary. Contrary to what one might expect, J.M. had greater difficulty learning new words during childhood than after the age of 18. This can be easily explained if we consider that during childhood, J.M. was not exposed to the foreign language continuously, but only in the classroom (1-2 hours per day) and a couple of hours outside the classroom, when watching English television programs. In contrast, in the United States he increased his vocabulary with great ease. I believe this was due to two factors: repetition and need. By repetition I mean that J.M. was now exposed to the language continuously. Marcotte and Morere (1990) showed that environmental deprivation leads to atypical brain organization as regards language functions. Marcotte and Morere’s study concentrated on first language acquisition, and we could hardly say that J.M. was deprived of learning the language; however, J.M.’s case agrees with Marcotte and Morere’s results in the following aspect: environmental factors play a very important role in language acquisition. In J.M.’s case, vocabulary repetition constitutes an environmental factor that is linguistic in nature. The need to communicate is of great importance for language acquisition; it is a big incentive to the learner. This need is the pressure that Hurford (1991) refers to when he argues that the capacity to acquire language “was helped to happen by selective pressure resulting from the enormous usefulness of language” (p.172), or when he argues that “the critical period effect “just happened”, and was allowed to happen because of the lack of selective pressure to acquire (more) language (or to acquire it again) once it has been acquired” (p. 172).
My argument is that there is no critical period for vocabulary, and that vocabulary can be acquired at advanced ages. In first language acquisition, the reason that the increase in children’s vocabulary is much greater than that of adults’ vocabulary is that children have a greater need to learn new words because their vocabulary is not rich enough at an early age, thus making communication difficult. J.M.’s case is similar to a child acquiring his first language. Although for J.M. English is his second language, he felt a similar need to communicate, since his English vocabulary was not rich enough, making communication difficult in his everyday life in the United States. The above conclusion agrees with that of Davis and Kelly (1997), whose “experiments examined the vocabulary component of language and […] did not find sensitive period effects” (p. 457). They add that although “one’s ability to learn the phonology and syntax of a new language later in life would be compromised, vocabulary acquisition is much more open-ended as new words are encountered throughout life. Thus there is a clear advantage to maintaining the ability to learn words” (p. 458).
Now let’s examine syntax and grammar. When J.M. arrived in the U.S. at the age of 18, his level of English syntax and grammar was already quite advanced. Great importance was placed on these two aspects of the language since he started learning it in Spain; in addition, due to similarities in syntax and grammar between English and Spanish, he didn’t have much difficulty reaching an advanced level quickly. This is why when he arrived in the U.S. there was no significant improvement observed, which we could have used to investigate whether there are critical age effects on syntax and grammar and whether syntax and grammar can be acquired after the critical period. However, we should keep in mind that J.M. started learning English at the age of 11. If there were a critical period for syntax and grammar, J.M. would not have been able to reach a native level. This conclusion is in agreement with Scovel (1998, cited in Gitterman, 1999), according to whom there is no support for a critical period for syntax. Nevertheless, this conclusion is not in agreement with Johnson et al. (1996) who concluded through discussion of experiments that grammatical performance of adult learners differs from that of native speakers qualitatively (i.e. not simply quantitatively). However, the results obtained by Johnson et al. may not be accurate, since, as they state in their study, “adult learners show a substantial amount of inconsistency in their judgments of grammaticality, and thus their performance is not well modeled by any simple or entirely deterministic model of underlying knowledge” (p.349).
So far we have examined vocabulary, syntax and grammar. But what happens when it comes to accent? Is there a critical period, after which one cannot learn to sound like a native speaker? Grimsaw et al (1998) examined the case of E.M., a man profoundly deaf since birth, who was provided with hearing aids at the age of fifteen. The language he acquired after that age was characterised by severe deficits in both verbal comprehension and production. This result favors the critical period hypothesis for first language acquisition. Gitterman (1999) examined Grimshaw et al.’s study and investigated whether the same conclusion can be drawn for second language acquisition. He concluded that there is certainly a critical period for phonological skills in second language acquisition. This conclusion agrees with that of Hakuta (1986, cited in Gitterman, 1999) and Scovel (1998, cited in Gitterman, 1999); “Scovel asserts that a loss of neuroplasticity in the brain of adults is the likely reason for the existence of a critical period for speech” (Gitterman, 1999, p. 378). In addition to Gitterman and Hakuta, Munro et al. (1996) also support the notion that there is a critical period for accent in second language acquisition. Munro et al. examined the hypothesis that production of English vowels depends on the age at which the second language is acquired. By examining English vowel production by native Italian speakers (but who had been living in an English-speaking environment for years), Munro et al. found that the presence of accent increased with age of arrival at the English-speaking environment. According to Long (1990) who studied the dependence of second language learning on age of acquisition, starting after age six appears to make it impossible for many learners to achieve native-like competence in phonology. Long attributes this lack of ability to achieve native-like competence in phonology to the loss of brain plasticity which happens with maturation. But what is that critical age, after which native-like competence in phonology is difficult to achieve? Johnson and Newport (1989) found that “performance gradually declined from about age seven on, until adulthood” (p. 95) (i.e. the decline begins far before puberty). Claude Hagège (1996), a French linguist, supports that the critical age is eleven years. Up to that age, he argues, the child can receive foreign sounds and the mouth can articulate them by imitation. At the age of 11 foreign sounds start being “filtered”, i.e. the child is no longer sensitive to sounds that do not exist in his native language. Lenneberg (1967, cited in Harley, 1995) suggested that the critical period ends at puberty.
The majority of studies seem to arrive at the conclusion that there is a critical period for second language acquisition as regards phonological skills. However, Bialystok (1997) argues that the evidence for a critical period for second language acquisition is not convincing. According to Bialystok, young learners acquire a second language with greater success than adult learners, but he attributes this success not to the existence of a critical period, but to other factors (such as the time one dedicates to language learning and motivation). Let’s examine J.M.’s case again, this time from a phonological perspective. When J.M. arrived in the U.S., he could hardly be understood; his accent was far from native. However, he had no difficulty at all in extracting (understanding) phonological information. For example, he pronounced the words “law” and “low” in exactly the same manner, although he could distinguish between the two when he heard them. Similarly, he produced / I / and /i/ in the same way (thus making no distinction between “feet” and “fit”), but had no trouble distinguishing the two when a native English speaker uttered them. Within a year after his arrival in the US, a significant improvement was observed. Although J.M. still did not sound like a native speaker, he could now be well understood. This observation shows that a phonological improvement can be achieved even after the age of eighteen. But is it possible to achieve native-like phonological competence after that age? During the following two years (age 18-20), J.M. continued to show phonological improvement, although this improvement was not significant (compared to the first year after his immersion into the English-speaking environment). How can we explain this decrease in phonological improvement? Can we argue then that 18 is the critical period for second language acquisition? At the age of 22, J.M. consulted a speech pathologist and had three one-hour sessions of “accent modification”. Tongue and lip positions required for production of various sounds were clearly explained to him. By using a mirror, J.M. could see whether he followed these mouth movements and compare them to those of the speech pathologist. In addition, J.M.’s sounds were recorded and replayed, so that he could observe himself where he needed improvement. After each session, J.M. practiced the sounds that he had worked on with the speech pathologist. After the treatment was finished, J.M. was able to produce the sounds he had worked on like a native speaker. For example, he could now produce the words “law” and “low” in a native-like manner. Unfortunately, the number of accent-modification sessions was not sufficient for an improvement in all of J.M.’s phonological difficulties. With more sessions and more practice, J.M. would likely have reached native-like phonological skills.
The answer to the question I posed earlier, i.e. how can we explain the decrease in J.M.’s phonological improvement, I believe is straightforward: he stopped trying; he did not dedicate any time or effort to practicing English sounds after his treatment was over. This conclusion is in perfect agreement with Bialystok (1997), according to whom adults can achieve the same success as children if they dedicate time and effort to language learning. As noted earlier, the decrease in J.M.’s phonological improvement started at the age of 18. Could this imply that 18 is the critical age? This contradicts most of the studies conducted on this subject, according to which this age is far beyond the critical period. However, this finding seems not to be in disagreement with Bialystok, who argues that the level where language noticeably declines is around the age of 20.
One could argue that J.M.’s case is an exception, and that we should not draw conclusions about what the critical period is based on this case. Therefore I will not use the study of J.M. as evidence to show that the critical period extends beyond the age of 18. I will rather use these findings to argue that the critical period is not a value common to each individual, but that it changes from person to person. Thus, although Claude Hagège argues that the age of eleven is a threshold for second language acquisition (and other researchers have suggested other critical ages), I argue that there is a critical period that differs among individuals, and that the loss of neuroplasticity is one of many factors (and certainly not the most important) that determine it. Other factors are motivation/need for communication, repetition, encouragement, relation between the native and the second language (shared features) etc.
Let’s examine how these factors affected J.M.’s phonological progress. The effect of motivation/need for communication has already been discussed; the need for communication was a very important factor in J.M.’s progress during the first year after his arrival in the United States. I believe that repetition also played a very important role during that first year. J.M. was now able to listen to English sounds repeatedly, and when he had doubts about the exact pronunciation of a word, he could easily verify it. As far as encouragement is concerned, it is a necessary factor so that an adult can practice producing different sounds exactly like a child does, without fear that he could make a mistake. Claude Hagège (1996) discusses this fear and considers it to be a big obstacle in an adult’s phonological progress. A child does not have a fear of being laughed at, if he does not pronounce a word correctly. An adult, on the other hand, is often afraid that he may produce sounds that will not sound native-like (for example, that he may over-aspirate a /p/ in the beginning of a word), and consequently he chooses to retain the sounds of his native language. J.M. certainly had that fear, but he made a great effort to overcome it when he realized that it was an obstacle to his being understood. J.M.’s speech pathologist gave him the encouragement he needed, as well as the option of trying to produce a particular sound many times until he produced it in a native-like manner. As regards non-shared features between English and Spanish, there are many. This is why J.M. had to put great effort into learning to produce new sounds. A bigger number of shared phonological features would facilitate the attainment of native-like pronunciation. This conclusion is in agreement with Bialystok (1997) who states that “the hypothesis is that language learners will find it difficult to master a structure that was not a defining feature of the first language and relatively easy to master a structure shared across the two languages. These differences may be exacerbated for older learners, but there should be no age differences in the ability to learn structures that are shared across the two languages” (p. 126). Although this statement does not refer specifically to accent, it is evident that it applies to accent, since no extra effort is needed to produce, in a second language, sounds that already have been mastered in one’s first language.
The examination of J.M.’s case in relation to the research conducted by linguists in second language acquisition, shows that there is no critical period for vocabulary, syntax and grammar, but that there is a critical period for phonological skills. This period is different among individuals, and is determined by several factors (and not simply by a loss of neuroplasticity), such as motivation, repetition, encouragement, and shared phonological features between one’s first and second language.
REFERENCES
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