Almost every human child succeeds in learning language. As a result, people often tend to take the process of language learning for granted. To many, language seems like a basic instinct, as simple as breathing or blinking. But language is not simple at all; in fact it is the most complex skill that a human being will ever master. That nearly all people succeed in learning this complex skill demonstrates how well language has adapted to human nature. In a very real sense, language is the complete expression of what it means to be human.
Linguists in the tradition of Noam Chomsky tend to think of language as having a universal core from which individual languages select out a particular configuration of features, parameters, and settings. As a result, they see language as an instinct that is driven by specifically human evolutionary adaptations. In their view, language resides in a unique mental organ that has been given as a "special gift" to the human species. This mental organ contains rules, constraints, and other structures that can be specified by linguistic analysis.
Psychologists and those linguists who reject the Chomskyan approach often view language learning from a very different perspective. To the psychologist, language acquisition is a window on the operation of the human mind. The patterns of language emerge not from a unique instinct but from the operation of general processes of evolution and cognition. For researchers who accept this emergentist approach, the goal of language acquisition studies is to understand how regularities in linguistic form emerge from the operation of low-level physical, neural, and social processes. Before considering the current state of the dialog between the view of language as a hard-wired instinct and the view of language as an emergent process, it will be useful to review a few basic facts about the shape of language acquisition and some of the methods that are used to study it.
The Basic Components of Human Language
Human language involves both receptive and productive use. Receptive language use occurs during the comprehension or understanding of words and sentences. Productive language use involves idea generation and the articulation of words in speech. Both reception and production utilize the four basic structural components of language:
- Phonology: The system of the sound segments that humans use to build up words. Each language has a different set of these segments or phonemes, and children quickly come to recognize and then produce the speech segments that are characteristic of their native language.
- Semantics: The system of meanings that are expressed by words and phrases. In order to serve as a means of communication between people, words must have a shared or conventional meaning. Picking out the correct meaning for each new word is a major learning task for children.
- Grammar: The system of rules by which words and phrases are arranged to make meaningful statements. Children need to learn how to use the ordering of words to mark grammatical functions such as subject or direct object.
- Pragmatics: The system of patterns that determine how humans can use language in particular social settings for particular conversational purposes. Children learn that conversations customarily begin with a greeting, require turn taking, and concern a shared topic. They come to adjust the content of their communications to match their listener's interests, knowledge, and language ability.
These four basic systems can be extended and elaborated when humans use language for special purposes, such as for poetry, song, legal documents, or scientific discourse. The literate control of language constructs additional complex social, cognitive, and linguistic structures that are built on top of the four basic structural components.
Methods for Studying Language Acquisition
The methods used to study language development are mostly quite straightforward. The primary method involves simply recording and transcribing what children say. This method can be applied even from birth. Tape recordings become particularly interesting, however, when the child begins systematic babbling and the first productions of words. Using videotape, researchers can link up the child's use of verbal means with their use of gesture and nonlinguistic cries to draw attention to their desires and interests.
Methods for studying comprehension are a bit more complicated. During the first year, researchers can habituate the infant to some pattern of sounds and then suddenly change that pattern to see if the infant notices the difference. From about nine months onward, children can be shown pictures of toys along with their names, and then researchers can measure whether the children prefer these pictures to some unnamed distracter pictures. Later on, children can be asked to answer questions, repeat sentences, or make judgments about grammar. Researchers can also study children by asking their parents to report about them. Parents can record the times when their children first use a given sound or word or first make some basic types of child errors. Each of these methods has different goals, and each also has unique possibilities and pitfalls associated with it. Having obtained a set of data from children or their parents, researchers next need to group these data into measures of particular types of language skills, such as vocabulary, sentences, concepts, or conversational abilities.
Phases in Language Development
William James (1890) described the world of the newborn as a "blooming, buzzing confusion." It is now known, however, that, on the auditory level at least, the newborn's world is remarkably well structured. The cochlea (in the inner ear) and the auditory nerve (which connects the inner ear with the brain) provide extensive preprocessing of signals for pitch and intensity. In the 1970s and 1980s, researchers discovered that human infants were specifically adapted at birth to perceive contrasts in sounds such as that between /p/and /b/, as in the words pit and bit. Subsequent research showed that even chinchillas are capable of making this distinction. This suggests that much of the basic structure of the infant's auditory world can be attributed to fundamental processes in the mammalian ear. Moreover, there is evidence that some of these early perceptual abilities are lost as the infant begins to acquire the distinctions actually used by the native language. Beyond this basic level of auditory processing, it appears that infants have a remarkable capacity to record and store sequences of auditory events. It is as if the infant has a tape recorder in the brain's auditory cortex that records input sounds, replays them, and accustoms the ear to their patterns.
Children tend to produce their first words sometime between nine and twelve months. One-year-olds have about 5 words in their vocabulary on average, although individual children may have none or as many as thirty; by two years of age, average vocabulary size is more than 150 words, with a range among individual children from as few as 10 to as many as 450 words. Children possess a vocabulary of about 14,000 words by six years of age; adults have an estimated average of 40,000 words in their working vocabulary at age forty. In order to achieve such a vocabulary, a child must learn to say at least a few new words each day from birth.
One of the best predictors of a child's vocabulary development is the amount and diversity of input the child receives. Researchers have found that verbal input can be as great as three times more available in educated families than in less educated families. These facts have led educators to suspect that basic and pervasive differences in the level of social support for language learning lie at the root of many learning problems in the later school years. Social interaction (quality of attachment; parent responsiveness, involvement, sensitivity, and control style) and general intellectual climate (providing enriching toys, reading books, encouraging attention to surroundings) predict developing language competence in children as well. Relatively uneducated and economically disadvantaged mothers talk less frequently to their children compared with more educated and affluent mothers, and correspondingly, children of less educated and less affluent mothers produce less speech. Socioeconomic status relates to both child vocabulary and to maternal vocabulary. Middle-class mothers expose their children to a richer vocabulary, with longer sentences and a greater number of word roots.
Whereas vocabulary development is marked by spectacular individual variation, the development of grammatical and syntactic skills is highly stable across children. Children's early one-word utterances do not yet trigger the need for syntactic patterns, because they are still only one-word long. By the middle of the second year, when children's vocabularies grow to between 50 and 100 words, they begin to combine words in what has been termed "telegraphic speech." Utterances typical of this period include forms such as "where Mommy," "my shoe," "dolly chair," and "allgone banana."
At this same time, children are busy learning to adjust their language to suit their audience and the situation. Learning the pragmatic social skills related to language is an ongoing process. Parents go to great efforts to teach their children to say "please" and "thank you" when needed, to be deferential in speaking to adults, to remember to issue an appropriate greeting when they meet someone, and not to interrupt when others are speaking. Children fine-tune their language skills to maintain conversations, tell stories, ask or argue for favors, or tattle on their classmates. Early on, they also begin to acquire the metalinguistic skills involved in thinking and making judgments about language.
As children move on to higher stages of language development and the acquisition of literacy, they depend increasingly on broader social institutions. They depend on Sunday school teachers for knowledge about Biblical language, prophets, and the geography of the Holy Land. They attend to science teachers to gain vocabulary and understandings about friction, molecular structures, the circulatory system, and DNA. They rely on peers to understand the language of the streets, verbal dueling, and the use of language for courtship. They rely on the media for role models, fantasies, and stereotypes. When they enter the workplace, they will rely on their coworkers to develop a literate understanding of work procedures, union rules, and methods for furthering their status. By reading to their children, telling stories, and engaging in supportive dialogs, parents set the stage for their children's entry into the world of literature and schooling. Here, again, the parent and teacher must teach by displaying examples of the execution and generation of a wide variety of detailed literate practices, ranging from learning to write through outlines to taking notes in lectures.
Special Gift or Emergence?
Having briefly covered the methods used to study language acquisition and the basic phases in development, it is now possible to return to this question: Is language development best characterized as the use of a "special gift" or as an emergent result of various cognitive, neural, physiological, and social pressures? There are good arguments in favor of each position.
The special gift position views language as an instinct. People are often overpowered by the "urge to speak." Young children must feel this urge when they interact with others and have not yet learned how to use words correctly. It is important to recognize, however, that crickets, birds, snakes, and many other species can be possessed by a similar urge to produce audible chirps, songs, and rattling. In themselves, these urges do not amount to a special gift for language learning. Better evidence for the special gift comes from the study of children who have been cut off from communication by cruel parents, ancient Pharaohs, or accidents of nature. The special gift position holds that, if the special gift for language is not exercised by some early age, perhaps six or seven, it will be lost forever. None of the isolation experiments that have been conducted, however, can be viewed as providing good evidence for this claim. In many cases, the children are isolated because they are brain-injured. In other cases, the isolation itself produces brain injury. In a few cases, children as old as six to eight years of age have successfully acquired language even after isolation. Thus, the most that can be concluded from these experiments is that it is unlikely that the special gift expires before age eight.
The second form of evidence in favor of the notion of a special gift comes from the observation that children are able to learn some grammatical structures without apparent guidance from the input. The argumentation involved here is sometimes rather subtle. For example, Chomsky noted that children would never produce "Is the boy who next in line is tall?" as a question deriving from the sentence "The boy who is next in line is tall." Instead, they will inevitably produce the question as, "Is the boy who is next in line tall?" That children always know which of the forms of the verb is to move to the front of the sentence, even without ever having heard such a sentence from their parents, indicates to Chomsky that language must be a special gift.
Although the details of Chomsky's argument are controversial, his basic insight here seems solid. There are some aspects of language that seem so fundamental that humans hardly need to learn them. Nevertheless, the specific structures examined by linguistic theory involve only a small set of core grammatical features. When looking more generally at the full shape of the systems of lexicon, phonology, pragmatics, and discourse, much greater individual variation in terms of overall language proficiency appears.
To explain these differences, it is necessary to view language learning as emerging from multiple sources of support. One source of support is the universal concept all humans have about what language can be. A second source of support is input from parents and peers. This input is most effective when it directly elaborates or expands on things the child has already said. For example, if the child says "Mommy go store," the parent can expand the child's production by saying "Yes, Mommy is going to the store." From expansions of this type, children can learn a wide variety of grammatical and lexical patterns. A third source of support is the brain itself. Through elaborate connections among auditory, vocal, relational, and memory areas, humans are able to store linguistic patterns and experiences for later processing. A fourth source of support are the generalizations that people produce when they systematize and extend language patterns. Recognizing that English verbs tend to produce their past tense by adding the suffix -ed, children can produce over-generalizations such as "goed" or "runned." Although these overgeneralizations are errors, they represent the productive use of linguistic creativity.
Individual children will vary markedly in the extent to which they can rely on these additional sources of support. Children of immigrant families will be forced to acquire the language of the new country not from their parents, but from others. Children with hearing impairments or the temporary impairments brought on by otitis media (ear infections) will have relatively less support for language learning from clear auditory input. Blind children will have good auditory support but relatively less support from visual cues. Children with differing patterns of brain lesions may have preserved auditory abilities, but impaired ability to control speech. Alternatively, other children will have only a few minor impairments to their short-term memory that affect the learning of new words.
Because language is based on such a wide variety of alternative cognitive skills, children can often compensate for deficits in one area by emphasizing their skills in another area. The case of Helen Keller is perhaps the best such example of compensation. Although Keller had lost both her hearing and her vision, she was able to learn words by observing how her guardian traced out patterns of letters in her hand. In this way, even when some of the normal supports are removed, children can still learn language. The basic uses of language are heavily over-determined by this rich system of multiple supports. As a child moves away from the basic uses of language into the more refined areas of literacy and specific genres, progress can slow. In these later periods, language is still supported by multiple sources, but each of the supports grows weaker, and progress toward the full competency required in the modern workplace is less inevitable.
See also: Bilingualism, Second Language Learning, AND English as a Second Language; Categorization and Concept Learning; Language and Education; Literacy and Reading.
Aslin, Richard N.; Pisoni, D. B.; Hennessey, B. L.; and Perey, A. J. 1981. "Discrimination of Voice Onset Time by Human Infants: New Findings and Implications for the Effects of Early Experience." Child Development 52:1135–1145.
Chomsky, Noam. 1982. Some Concepts and Consequences of the Theory of Government and Binding. Cambridge, MA: MIT Press.
Fenson, Larry, et al. 1994. Variability in Early Communication Development. Chicago: University of Chicago Press.
Fletcher, Paul, and MacWhinney, Brian, eds. 1995. The Handbook of Child Language. Oxford: Blackwell.
Hart, Betty, and Risley, Todd R. 1995. Meaningful Differences in the Everyday Experience of Young American Children. Baltimore: Brookes.
Huttenlocher, Janellen; Haight, W.; Bryk, Anthony; Seltzer, M.; and Lyons, T. 1991. "Early Vocabulary Growth: Relation to Language Input and Gender." Developmental Psychology 27:236–248.
James, William. 1890. The Principles of Psychology. New York: Holt, Rinehart and Winston.
Keil, Frank C. 1989. Concepts, Kinds, and Cognitive Development. Cambridge, MA: MIT Press.
Lenneberg, Eric H. 1967. Biological Foundations of Language. New York: Wiley.
MaCWhinney, Brian. 2000. The CHILDES Project: Tools for Analyzing Talk. Mahwah, NJ: Erlbaum.
McCarthy, D. 1954. "Manual of Child Psychology." In Language Development in Children, ed. L. Carmichael. New York: Wiley.
Piatelli-Palmarini, Massimo. 1980. Language and Learning: The Debate between Jean Piaget and Noam Chomsky. Cambridge, MA: Harvard University Press.
Pinker, Steven. 1994. The Language Instinct. New York: Morrow.
Saffran, Jenny; Aslin, Richard; and Newport, Elissa. 1996. "Statistical Learning by Eight-Month-Old Infants." Science 274:1926–1928.
Templin, Mildred. 1957. Certain Language Skills in Children. Minneapolis: University of Minnesota Press.
VAN Ijzendoorn, Marinus H.; Dijkstra, J.; and Bus, A. G. 1995. "Attachment, Intelligence, and Language: A Meta-analysis." Social Development 4:115–128.
Werker, Janet F. 1995. "Exploring Developmental Changes in Cross-Language Speech Perception." In An Invitation to Cognitive Science, Vol.1: Language, ed. Lila Gleitman and Mark Liberman. Cambridge, MA: MIT Press.
"Language Acquisition." Encyclopedia of Education. . Encyclopedia.com. (October 17, 2017). http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/language-acquisition
"Language Acquisition." Encyclopedia of Education. . Retrieved October 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/language-acquisition
CHILD LANGUAGE ACQUISITION
Child developmentIt is commonplace to talk of ‘milestones’ in relation to child development in general, but this metaphor does not work as precisely for the development of speech. Sounds, grammar, vocabulary, and social linguistic skills are emerging simultaneously but at different rates, and significant progress can be made on several fronts in a matter of days. There are also many individual differences in the order of acquisition of specific features of language which need to be taken into account. However, most children appear to follow a similar path as they acquire sounds and grammatical structures, and broad similarities have been observed in relation to types of vocabulary and conversational skills. The aim of child language research is to explain the basis of this common order of emergence, allowing for the complex kinds of individual variation which are readily apparent.
Theoretical approachesSeveral approaches have been applied to child language data. Certain features of the data seem to be the result of the children imitating what they hear in adult speech (for example, some of the early attempts at sound patterns, and the acquisition of new words), but very little of grammatical structure is learned by simple imitation. This was early noticed by researchers, who pointed out that child coinages such as mouses for mice or goned for gone could not have been produced through a process of imitation (for adults do not say such things), but must represent the child's own application of abstract rules already acquired. Furthermore, direct correction and coaching have very little effect, showing the important role of the child's own efforts. Various ways of explaining this internal ability were proposed, most notably CHOMSKY'S argument that children must be credited with an innate language acquisition device: a set of outline principles about the way language is structured and a procedure for discovering the remainder. Investigators such as Piaget argued for the importance of relating the emergence of children's language to their underlying intellectual or cognitive development. Others stressed the importance of analysing the nature of the input presented to them by adult speakers. It is now apparent that each of these factors has a role to play in guiding the course of acquisition, but the nature of their interdependence is far from clear.
Stages of developmentAt a descriptive level, considerable progress has been made, especially for ENGLISH, in establishing the order of emergence of sounds, grammatical structures, and (to a lesser extent) vocabulary, and determining the psycholinguistic principles involved. The focus has been on the earliest years, including the prelinguistic period of the first year. Between birth and 12 months, several stages can be detected in a child's emerging sound-producing and perceptual abilities, beginning with a range of basic biological noises reflecting such states as hunger, pain, discomfort, and contentment (0–8 weeks), and proceeding to a stage of cooing and laughing (8–20 weeks), vocal play (20–30 weeks), babbling (25–50 weeks), and the first melodically shaped utterances (9–18 months). At around a year, first words appear, though these are not easily identified with the words of the adult lexicon, but tend to have idiosyncratic meanings and to be used as primitive sentences (holophrases). Dada, for example, said with appropriate intonation and gesture, might mean ‘There's daddy’ or ‘Where's daddy?’ or ‘Pick me up, daddy’. Moreover, the word dada might refer at this stage not only to the male parent, but also to the female parent, or to other adults, or to certain animals, or even to objects. From 12 months, an expressive vocabulary is acquired which by 18 months is usually around 50 words in size. By that time, children understand far more words than they produce: estimates suggest three or four times as many. In the next six months, expressive vocabulary approaches 200 words, and in the third year rapidly moves into the thousands. Detailed studies of the growth in vocabulary size in older children are as yet unavailable, though several studies have been made of the processes which seem to affect children's lexical progress, such as over-extension of meaning, as when dog is used for all animals, and under-extension, as when dog is used for one kind of dog only.
Pronunciation and grammarMost research time has been devoted to the emergence of PRONUNCIATION and GRAMMAR. Children do not learn all their sounds in an identical order, but seem to share certain general tendencies. Most English CONSONANTS are acquired between the ages of 2 and 4 years. Moreover, within this sequence, certain important trends have been established. For example, consonants are more likely to be first used correctly at the beginnings of words, with final consonants emerging later. Several processes of simplifying pronunciation have been identified in early speech, such as the avoidance of consonant clusters (sky pronounced without the s), the dropping of an unstressed syllable (banana pronounced as nana), or the replacement of fricative sounds such as [f] and [s] by plosive sounds such as [p] and [t]: for example, shoe as /tuː/ and fish as /pɪ/. During the second year, some children make great use of a process of REDUPLICATION, with the different syllables of a word being pronounced in the same way, as when (in one child) sister became [sisi] and mouth became [muːmuː]. Patterns of INTONATION also develop in the early years (such as the difference between stating and questioning, using the melody of the voice only), but some of the more subtle intonation patterns are still being learned as late as the teenage years, such as the difference between I THOUGHT it would rain (and it has) and I thought it would RAIN (but it hasn't).
Grammatical patterns in the early years are fairly well established for English. A stage of single-word SENTENCES appears from just before 12 months of age until 18 months, such as bye, gone, teddy, and mama. At around 18 months, children begin to put two words together, to make simple ‘telegrammatic’ sentences such as dada bye, want car, and mine lorry. Sentences increase in complexity during the third year, with more advanced features of CLAUSE structure being introduced. Clauses add extra elements, stabilizing word order, and developing a clearer subject-verb-object structure; and the hierarchical structure of a sentence develops, with phrasal complexity emerging within clauses, and ridding the sentences of their telegrammatic appearance. My daddy do kick that ball is a typical sentence for a 2-year-old. Each of the elements (subject, verb, object) appears as more than one word (a phrase), so that the sentence now has two layers of structure. By age 3, there is still greater complexity, in the form of linked sequences of clauses, using such words as and, but, cos (for ‘because’), and then.
Narratives, sometimes of great length, now make their appearance. As sentence control develops, so more attention is paid to the more subtle aspects of grammar, such as the learning of the irregular forms of nouns, verbs, pronouns, and other parts of speech. At 3, most children are making errors in the use of certain pronouns (such as me not like that mouse); by 4, most such errors have been eliminated. During the early school years there are still several aspects of English grammar to be acquired, such as the rarer irregular forms, more complex patterns of sentence connection (such as the use of although), and the use of multiple subordinate clauses. There is evidence of grammatical development right through the primary school years until, as the teenage years approach, all that is left is the learning of more subtle aspects of grammatical style and the building up of vocabulary.
Other skillsThe task of language acquistion requires more than the learning of the structural skills of sounds, grammar, and vocabulary. Children must also learn to use these structures appropriately in everyday situations. They need to develop conversational skills, the rules of politeness (such as when to say please and thank you), the correct use of FORMS OF ADDRESS, and how to make requests in a direct or indirect manner (‘I was wondering if you could …’). Older children need to be able to handle such ‘manipulating’ features of language as well, you know, and actually, to learn to decode and use more subtle interactional features (such as sarcasm), and to cope with such stylistic differences as formal and informal speech. School brings an encounter with learning to read and write, though for many children considerable awareness of written language has come from reading materials at home. Finally, children have to develop a set of metalinguistic skills (the ability to reflect on and talk about language), through the use of a range of popular, semi-technical, and technical notions, such as sound, word, page, sentence, capital letter. The task of language acquisition is complex. The fact that it is largely complete by puberty makes it one of the most remarkable (if not the most remarkable) of all learning achievements. See ANALOGY, HALLIDAY, LANGUAGE LEARNING, PSYCHOLINGUISTICS.
"CHILD LANGUAGE ACQUISITION." Concise Oxford Companion to the English Language. . Encyclopedia.com. (October 17, 2017). http://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/child-language-acquisition
"CHILD LANGUAGE ACQUISITION." Concise Oxford Companion to the English Language. . Retrieved October 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/child-language-acquisition
language acquisition, the process of learning a native or a second language. The acquisition of native languages is studied primarily by developmental psychologists and psycholinguists. Although how children learn to speak is not perfectly understood, most explanations involve both the observation that children copy what they hear and the inference that human beings have a natural aptitude for understanding grammar. While children usually learn the sounds and vocabulary of their native language through imitation, grammar is seldom taught to them explicitly; that they nonetheless rapidly acquire the ability to speak grammatically supports the theory advanced by Noam Chomsky and other proponents of transformational grammar. According to this view, children are able to learn the
grammar of a particular language because all intelligible languages are founded on a
of grammatical rules that are universal and that correspond to an innate capacity of the human brain. Stages in the acquisition of a native language can be measured by the increasing complexity and originality of a child's utterances. Children at first may overgeneralize grammatical rules and say, for example, goed (meaning went), a form they are unlikely to have heard, suggesting that they have intuited or deduced complex grammatical rules (here, how to conjugate regular verbs) and failed only to learn exceptions that cannot be predicted from a knowledge of the grammar alone. The acquisition of second or foreign languages is studied primarily by applied linguists. People learning a second language pass through some of the same stages, including overgeneralization, as do children learning their native language. However, people rarely become as fluent in a second language as in their native tongue. Some linguists see the earliest years of childhood as a critical period, after which the brain loses much of its facility for assimilating new languages. Most traditional methods for learning a second language involve some systematic approach to the analysis and comprehension of grammar as well as to the memorization of vocabulary. The cognitive approach, increasingly favored by experts in language acquisition, emphasizes extemporaneous conversation, immersion, and other techniques intended to simulate the environment in which most people acquire their native language as children.
See J. C. Richards, Error Analysis: Perspectives on Second Language Acquisition (1974); R. Andersen, ed., New Dimensions in Second Language Acquisition Research (1981); D. W. Carroll, Psychology of Language (1986); A. Radford, Syntactic Theory and the Acquisition of English Syntax (1990).
"language acquisition." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (October 17, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/language-acquisition
"language acquisition." The Columbia Encyclopedia, 6th ed.. . Retrieved October 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/language-acquisition
LANGUAGE ACQUISITION DEVICE
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"LANGUAGE ACQUISITION DEVICE." Concise Oxford Companion to the English Language. . Retrieved October 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/language-acquisition-device