Introducing Second Language Acquisition. Kirsten M. Hummel

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.

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