Читать книгу Introducing Second Language Acquisition - Kirsten M. Hummel - Страница 20

Babies are born into the world unable to linguistically articulate specific desires, needs, feelings, or intentions. However, as anyone who has had any experience with infants realizes, babies do manage to communicate in very vocal and physical ways, through various forms and intensities of crying, cooing, other sounds, and by using physical movements and gestures. In the space of a few short months, such responses come to be gradually replaced by more language‐like sounds and by 12 months of age many children are already uttering their first words.

Considerable research has gone into examining the L1 acquisition process and much of this information reveals that infants appear to come into the world equipped to acquire the language they are exposed to in their environment. Linguists often use the term “prewired” to describe this state of readiness. In fact, many linguists argue that innate structures are the only reasonable explanation for the rapidity of development and universality of stages that characterize L1 acquisition. Noam Chomsky, the pre‐eminent linguist of our times, uses the analogy of a child “learning” to walk: the child does not need to be taught to walk, he or she simply begins to put one foot ahead of the other, as soon as the child is able to stand erect (Searchinger 1995). Similarly, acquiring the language used in one's environment unfolds in the same way: children do not need to be deliberately “taught” to speak, they simply begin to do so.

Substantial evidence supports the idea of a genetic predisposition for language. For instance, a number of studies have shown that infants show a preference for the human voice, and in particular for the mother's voice, as young as three days old (DeCasper and Fifer 1980). The preferences of very young infants can be measured using a technique known as high amplitude sucking ( HAS ). In this technique, infants are exposed to sounds while their sucking rate on a pacifier is measured; an increase in rate is thought to indicate increased interest as well as the infant's detection of a stimulus difference. This technique therefore capitalizes on several facts: babies like to hear sounds; they lose interest when a sound is presented repeatedly; and they regain interest when a new sound is presented. The HAS technique is reliable from approximately one to four months of age.

high amplitude sucking (HAS)

A technique used to study infant perceptual abilities; typically involves recording an infant's sucking rate as a measure of its attention to various stimuli.

Cartoon 2.1 Mike Baldwin/CartoonStock.com.

The HAS technique has revealed that newborns prefer speech sounds to non‐speech sounds (Vouloumanos and Werker 2007). Young infants also prefer looking at the human face, and prefer gazing at mouth movements that move in synchrony with the speech produced by those movements. The groundwork for conversational interaction is apparent in the early gaze‐coupling, or eye contact, behavior between the caregiver and the infant. Even at early pre‐verbal stages, interactional patterns characterize infant–caregiver communication; for example, infants wait for adult vocalizations in response to their own, and their sounds become more speech‐like following adult speech addressed to them.

Another remarkable finding is that young children from many different cultures and languages of origin are able to perceive a multitude of sound differences, even those not occurring in the language of their environment, an ability known as “sound” or “auditory discrimination,” while adults are often unable to differentiate those same sounds if they are not used in the native language. However, by the ages of 10–12 months, this sound discrimination ability already begins to disappear if the distinction is not reinforced as a part of the language spoken in that child's environment. For instance, in a study involving adults and infants, researchers (Werker and Tees 1984) examined a contrast occurring in Hindi which involved dental (tongue against the teeth) and retroflex (with the tongue curled back in the mouth) variants of the sound “t” (/t/ vs /ṭ/), a contrast that does not occur in English. While Hindi‐speaking adults are able to perceive this sound difference without difficulty, English‐speaking adults generally are unable to do so. Werker and Tees examined children's perceptual abilities for the Hindi contrast, as well as for a Salish (a language spoken by First Nations people in British Columbia) contrast between two consonantal sounds produced in the back part of the mouth: velar /k'i/and uvular /q'i/. This experiment focused on head‐turning responses of young infants (infants are found to turn their head when they detect a novel stimuli), and the researchers found that six‐ to eight‐month‐old English‐speaking infants were able to perceive the Hindi contrast, as well as the Salish contrast. However, by 8–10 months, the infants could no longer perceive the Salish contrast. And by 10–12 months of age, the children no longer perceived the Hindi contrast either. In contrast, children from native Hindi‐ and Salish‐speaking families continued to perceive the contrasts occurring in their native languages. The results for English L1 and Hindi L1 infant perception of Hindi contrasts are illustrated in Figure 2.1.

Figure 2.1 English L1 and Hindi L1 infant perception of Hindi consonant contrasts.

Source: Based on Werker, J., & Tees, R. (1984).

Numerous other studies examining other sound distinctions and languages of different types have found similar results (Estonian vs Finnish vowels: Cheour et al. 1998; German vowels: Polka and Werker 1994; Catalan vowels: Bosch and Sebastián‐Gallés 2003). It appears that certain sound contrast perceptions are not maintained if those contrasts are not used in the infant's language environment. It is thought that this winnowing out of unnecessary perceptive distinctions allows the child to reserve mental space for those contrasts that are important in his or her language.

Table 2.1 Development of babbling.

Source: Based on Davis, B.L., & MacNeilage, P.F. (1995). The articulatory basis of babbling. Journal of Speech and Hearing Research, 38, 1199–1211.

4–6 months onset	Marginal babbling
6–8 months onset	Vocal play (low and high sounds). Babbling: reduplicated babbling (bababa) predominates first, followed by non‐reduplicated, or variegated babbling (badagu)
8–12 months onset	Jargon, or conversational babbling

Another argument that children come “prewired” for language is the fact that despite significant geographic and cultural differences, babies all over the world appear to go through similar linguistic stages and reach linguistic milestones at similar ages, although at the same time, there is also a certain amount of individual variation associated with the specific ages for those milestones. The first recognizable pre‐linguistic stage is that of “babbling,” occurring as early as three to four months of age, when the infant begins to produce a certain number of distinct sounds, usually taking the form of a consonant‐vowel (CV) sequence (see Table 2.1 for stages of babbling). Studies (e.g. Davis and MacNeilage 1995) have shown that certain combinations are more frequent than others cross‐culturally.

For instance, bilabial stops (sounds like p, b, and m, produced using the lips) tend to be quite frequent in babbling, and are often associated with the low, back vowel “a,” giving a sequence such as “ba‐ba‐ba.” Sounds not frequently found in babbling across languages include the liquids /r/ and /l/. An early phase of babbling is sometimes referred to as reduplicated babbling since the CV sequences tend to be repeated. Later on, nonreduplicated or “variegated” babbling begins to predominate since infants begin to vary the particular CV sequences they produce (e.g. “ba‐ga‐da”). Nor is babbling restricted to the vocal channel; interestingly, it has been found that deaf children raised by signing parents tend to engage in manual babbling from approximately seven months of age (e.g. Petitto and Marentette 1991). Their manual babbling has its own distinctive rhythm and occurs in the same “signing space” that is normally used for sign languages.

reduplicated babbling

Babbling in which CV combinations are repeated, such as “ba‐ba‐ba.”

nonreduplicated babbling (variegated)

Babbling in which young children vary the CV sequences used; for example, “ba‐da‐ga.”

Some correspondence has been found between babbling and later language. For instance, in a study of French, English, Japanese, and Swedish L1 infants, beginning at 10 months of age, the proportion of labial (produced with one or both lips) vocalizations was found to be related to the proportion of those used in the child's language environment (Vihman et al. 1994).

Children seem able to comprehend their first words between 7 and 10 months, although some children are in advance of, or behind, their peers. A landmark in linguistic development occurs at approximately one year of age, at the same time that many young children are beginning to take their first step, when a first recognizable word may be heard (e.g. “mama” or “da” for dog). This “first‐word” stage is sometimes called the “holophrastic” stage, derived from the Greek words “holo” (one) and “phrastic” (phrase or sentence), referring to the idea that the single words appear to substitute for the thought conveyed in a full sentence.

First words are often produced in a form somewhat different from the target adult word. Phonological processes, such as assimilation, in which a sound is produced in a similar manner to a neighboring sound (e.g. “z” which is voiced, instead of voiceless “s” before a voiced vowel) or substitution of sounds (e.g. “t” instead of “s”) may be applied unconsciously by the child, facilitating the child's articulation of the target word. Another common process occurs when an initial consonant cluster (sequence of two consonants, as in “kl”) is simplified by omission of one of the consonants, as in “keen” for “clean.”

The transition from babbling to single words is not abrupt: children continue to babble sounds at the same time as they begin to produce early words. However, eventually, fewer babblings occur and single words come to predominate in the child's speech.

First words tend to name people and objects common in the child's universe: mama, papa, cat, juice, cookie, etc. Nouns tend to predominate, forming close to 50% of word types for young children. Other word categories consist of verbs or action words (“go,” “up,” etc.), modifiers (“big,” “fast”), and social/personal words (“hi,” “bye”).

Another common occurrence in early word learning is the child's use of a word beyond its usual sphere of reference, known as overextension. An example of this is a child's use of the word “cat” while pointing to any four‐footed creature in the local pet shop: dogs, mice, or even furry ferrets. Underextension, when a word is used less broadly than its true domain of reference, also occurs, although it is more difficult to detect, since it is not as obvious if a child is failing to provide a label as when actually mislabeling as in overextension. An example of underextension is a child using the word “dog” only for his or her pet collie, but not for the neighbor's pet poodle. Various estimates suggest as many as 30% of words are overextended at least some of the time during the first two years of the child (e.g. Clark 1993; Rescorla 1980). By 2.5 years of age, however, only rare occasions of over‐ or underextensions are thought to occur.

overextension

A child's use of a word for objects or items that share a feature or property; for example, using “dog” to refer to all animals with four legs.

underextension

A child's use of a word with a narrower meaning than in the adult's language; for example, “dog” to refer only to the family's pet.