PHONOLOGICAL DEVELOPMENT • From birth, children are exposed to a variety of noises in their environment. • Before they can begin to acquire language, they must first separate non- speech noises from speech sounds. • The rudiments of this ability seem to be present at birth, since even newborns respond differently to human voices than to other sounds. • Within 2 months of birth, infants can even recognize their mother's voice.
Babbling • Even before children master the phonemic contrasts of their language, they begin to develop the articulatory movements needed to produce these distinctions in speech. • The emergence of articulatory skills begins around 3 or 4 months of age, when children start to produce cooing and babbling sounds.
As a group, vowels are acquired before consonants (by age three). • Stops tend to be acquired before other consonants. • In terms of place of articulation, labials are acquired first, followed, with some variation, by velars, alveolars, and alveopalatals. Interdentals (such as [θ] and [ð]) are acquired last. • New phonemic contrasts manifest themselves first in word-initial position. Thus, the /p/ -/b/ contrast, for instance, will be manifested in pairs such as pat-bat before mop-mob. • All other things being equal, a sound that occurs in many different words will be acquired before a sound (like [ð] in English) that occurs in relatively few words.
Early Phonetic Processes • The phonetic processes responsible for the speech patterns of young language learners are not arbitrary. • For the most part, these processes simplify phonological structure by creating sound patterns that can be articulated with a minimum of difficulty. Such patterns are typified by syllables consisting of a consonant and a vowel. • SubstitutionOne of the most widespread phonetic processes in child language involves substitution-the systematic replacement of one sound by another. Common substitution processes include • Stopping: the replacement of a fricative by a corresponding stop; • Fronting: the moving forward of a sound's place of articulation; • Gliding:the replacement of a liquid by a glide; • Denasalization:the replacement of a nasal stop by a nonnasal counterpart. These processes are illustrated with the help of English examples in the next slide.
Syllable Simplification : A second type of process in children's speech involves the systematic deletion of certain sounds resulting in simpler syllable structure. In the data below typical of the speech of two- and three-year-old children, consonant clusters have been reduced by deleting one or more segments. • In all of these patterns, the weaker segment in the cluster is deleted. Thus, stops are retained over all other consonants, and fricatives are retained over liquids
Another common deletion process in two-year-old children involves the elimination of final consonants. Initial consonants, in contrast, are typically retained if they precede a vowel. • Both the reduction of consonant clusters and the deletion of final consonants have the effect of simplifying syllable structure, bringing it closer to the CV pattern that is universally favored by children and that is the most widely found pattern in language.
Assimilation :is the modification of one or more features of a phoneme under the influence of neighboring sounds. • In the following examples, initial consonants have been voiced in anticipation of the following vowel tell [dɛl] ; push [bʊs] ; soup [zuwp] ; pig [bɪg] • In the next set of examples, a word-final consonant is devoiced in apparent anticipation of the silence following the end of an utterance. have [hæf] ; big [bɪg] ; egg [ɛk] , bed [bɛt] . • Assimilation is also observed in children's tendency to maintain the same place of articulation for all of the vowels or consonants in a word. This can lead to the pronunciation of doggy as [gagij] (with two velar stops) or as [dodij] (with two alveolar stops).
Thus, they may initially produce the correct plural form for man and the correct past tense for come. • As they subsequently observe the generality of -s as a plural marker and -ed as a past tense marker around the age of two years and six months , they may incorrectly add these suffixes to the irregular forms-producing words such as *mans and *runned. (Errors resulting from overgeneralizations.) • For a period of several months, the over generalized forms and their correct counterparts may co-occur in children's speech. Even occasional mixed forms such as felled, a blend of fell and falled, may be used before children come to distinguish between inflected forms that follow a general rule and those that must be treated as exceptions. • The development of affixes • Stage 1: case-by-case learning .Stage 2: overuse of general rule. • Stage 3: learning of exceptions to the general rule . Stage 4: production of adult forms .
Word Formation Rules Like inflectional morphemes, English derivational affixes and compounding appear to be acquired in a more or less fixed order. This is illustrated in a study of the six word formation processes as follows
DEVELDPMENT OF WORD MEANING • By age 18 months or so, the average child has a vocabulary of 50 words or more. • Over the next months this vocabulary grows rapidly, sometimes by as much as ten or 12 words a day. The typical words of a two-year-old child are : • Objects • body parts: cheek, ear, foot, hand, leg, nose, toe • food: cookie, cereal, drink, egg, fish, jam, milk clothes: boot, clothes, dress, hat, shirt, shoes, socks • household:bag, bath, bell, bottle, box, brush, chair, clock, soap, spoon, • animals:bear, bird, cat, cow, dog, horse, sheep • Properties • bad, dirty, fat, good, more, nice, poor, sweet • Actions and events • bring, burn, carry, catch, clap, come, cut, do, dry, fall, get, give, go, kick, kiss, knit, look, meet, open, pull, push, ring, shut, sit, sleep, speak, sweep, tickle, wag, warm, wash • Other • away, down, now, up, no, yes, thank you, goodbye
The crucial factor in determining the order of emergence of these word formation processes seems to be productivity. • The two processes that apply most freely in English (the formation of a noun by the addition of the agentive affix -er to a verb and compounding) were the first to emerge. • On the other hand, morphemes such as -ly that can apply to only a restricted set of adjectival roots (quiet/quietly but *red/redly, *fast/fastly) seem to be mastered at a much later age. • Noun- like words are predominant in the child's early vocabulary, with verb- and adjective-like words being the next most frequent category types. noun-like verbs adjectives • Among the most frequent individual words are expressions for displeasure or rejection (such as no) and various types of social interaction ( such as give and bye-bye). • Over the next few years, continued rapid expansion of this vocabulary takes pace so that by age six most children have mastered about five thousand different morphemes. • 6yrs 5000 words • These developmental trends are found in all linguistic communities and therefore appear to be universal.
A major factor in lexical development is the child's ability to use contextual clues to draw inferences a out t e category and meaning of new words. • From around 17 months of age, for instance, children can use the presence or absence of determiners to distinguish between proper nouns (names) and common nouns. • 2 year-old children who are told that a new doll is a dax will identify a similar doll as a dax as well. However, if they are told that the new doll is Dax, they will restrict use of the new word to the doll they have actually been shown. • Children are also able to use the meaning of other words in the sentence as well as their understanding of the nonlinguistic context to form hypotheses about new words. • In one experiment, for example, 3 and 4-year-old children were asked to act out the meaning of sentences such as "Make it so there is tiv to drink in this glass (of water)." The only clues to the interpretation of the nonsense word tiv come from the meaning of the sentence and from the child's understanding of the types of changes that can be made to a glass of water. Not only did more than half the children respond by either adding or removing water, some even remembered what tiv "meant" two weeks later!
Errors in the Acquisition of Word Meaning • The meanings that children associate with their early words sometimes correspond closely to the meanings employed by adults. In many cases, however, the match is less than perfect. The two most typical semantic errors involve overextension and underextension. • Overextension In cases of overextension, the meaning of the child's word overlaps with that of the corresponding adult form, but also extends beyond it. The word dog, for example, is frequently overextended to include horses, cows, and other four-legged animals. Similarly, ball is sometimes used for any round object, such as a balloon,, a small stone, a plastic egg-shaped toy, and so on. • What is the basis for overextension? Is it the similarities in the appearance (shape, size, texture )or the function of object to which the overextended word refers?
Children often overextend a word to include a set of perceptually similar objects that they know to have diverse functions. One child,· for example, used the word moon for the moon, grapefruit halves, a crescent- shaped piece of paper, a crescent-shaped car light, and a hangnail. Another child used the word money for a set of objects ranging from pennies to buttons . • While overextensions are the most frequent type of word meaning error among children also frequently employ underextension. • Underextension: using lexical items in an overly restrictive fashion. For example, at the age of 9 months, one child restricted her use of the word car to a particular situation. She used it only for cars moving on the street as she watched out of the window, not for cars standing still, for cars in pictures, or for cars she rode in herself. • Another type of underextension is the use of a word to name a specific object without extending it to other members of that class. Thus, kitty might be used to refer to the family pet, but not to any other cats.
SYNTACTIC DEVELOPMENT • Like phonological and morphological development, the emergence of syntactic rules takes place in an orderly sequence. • Beginning with the production of one-word utterances near the end of the first, children gradually master the rules for sentence formation in their language. • One Word Stage Children begin to produce one-word utterances between the ages of 12 and 18 months. A basic property of these one-word utterances is that they can be used to express the type of meaning that would be associated with an entire sentence in adult speech. Thus, a child might use the word dadato assert (among other things) 'I saw daddy's hat', more to mean 'Give me more candy', and upto mean 'I want up'. Such utterances are called holopbrases. • A striking feature of holophrastic utterances is children's skill in communicating complex messages with a single word. This skill seems to be based on a strategy of choosing the most informative word that applies to the situation being commented upon. A child who wanted a candy, for example, would say candyrather than wantsince the former word is more informative in this situation. Similarly, a child who notices a new toy would be more likely to say toythan see,thereby referring to the most novel feature of the situation he/she is trying to describe.
While the production is restricted to single-word utterances, children at this stage seem to have acquired more complex form of syntactic knowledge.
II) The TwoWord Stage : Within a few months of their first one word utterances, children begin to produce two-word utterances of the sort shown below III) The Telegraphic Stage : After a period of several months during which their speech is limited to one- and two-word utterances, children begin to produce longer and more complex grammatical structures. Some representative utterances from the first part of this period are given in the following example. Chair all broken. Man ride bus today. What her name Me wanna show Mommy. I good boy. Daddy like this book.