2: Early Language Development

2: Early Language Development • Outline • What we need to learn language • The sequence of language acquisition • Can language be learned? • behaviorist theories • Nativist theories • Constructivist theories • Conclusion • Learning Outcomes

Learning a Language Involves... • Learning the language’s sounds and sound patterns, its specific words, and the ways in which the language allows words to be combined • Using the finite set of words in our vocabulary, we can put together an infinite number of sentences and express an infinite number of ideas—a process described as generativity

Required Competencies for Learning Language • Phonological development: The acquisition of knowledge about phonemes, the elementary units of sound that distinguish meaning • Semantic development: Learning the system for expressing meaning in a language, beginning with morphemes, the smallest unit of meaning in a language • Syntactic development: Learning the syntax or rules for combining words • Pragmatic development: Acquiring knowledge of how language is used, which includes understanding a variety of conversational conventions

Humans and Language • Language is a species-specific behavior: Only humans acquire a communication system with the complexity, structure, and generativity of language • Language is also species-universal:Virtually all humans develop language • Although some nonhuman primates have been trained to use signs or other symbols after concentrated effect by humans, there appears to be little evidence that they have acquired syntax

Language and the Brain • Studies of individuals with brain damage resulting in aphasia provide evidence of specialization for language within the left hemisphere • Damage to Broca’s area, near the motor cortex, is associated with difficulties in producing speech • Damage to Wernicke’s area, which is near the auditory cortex, is linked to difficulties with meaning • Language processing involves a substantial degree of functional localization in the brain • The left hemisphere shows some specialization for language in infancy, although the degree of hemispheric specialization for language increases with age

Language and the Brain

Critical Period • To learn language, children must also be exposed to other people using language—spoken or signed • Sometime between age 5 and puberty, language acquisition becomes much more difficult and ultimately less successful • Difficulties feral children (such as Genie) have in acquiring language in adolescence • Comparisons of the effects of brain damage suffered at different ages on language • Language capabilities of bilingual adults who acquired their second language at different ages • Knowledge of the fine points of English grammar, for example, was related to the age at which individuals were exposed to English, but not to the total length of their exposure to the language

Test of the Critical-Period Hypothesis • Performance on a test of English grammar by adults originally from Korea and China was directly related to the age at which they came to the United States and were exposed to English • The scores of adults who emigrated before the age of 7 are indistinguishable from those of native English speakers

Infant-Directed Talk (Child-Directed Speech) • The distinctive mode of speech that adults adopt when talking to babies and very young children • It is common throughout the world, but it is not universal • Its characteristics include a warm and affectionate tone, high pitch, extreme intonation, and slower speech accompanied by exaggerated facial expressions • Infants prefer IDT (CDS) to speech directed to adults

Prosody • Infants know a great deal about language long before their first linguistic productions • Fetuses appear to be sensitive to prosody, the characteristic rhythm, tempo, cadence, melody, intonational patterns, and so forth with which a language is spoken • Variations in prosody are in large part responsible for why languages sound so different from one another, and why speakers of the same language can sound so distinctive

Phonemic Perception • Infants are born with the ability to discriminate between speech sounds in any language • This capacity primes them to start learning any language in the world • Beginning at around 7 months, however, infants gradually begin to specialize, retaining sensitivity to sounds they hear and losing the capacity to discriminate among sounds to which they are not exposed • By the end of the first year of life, infants’ speech perception is similar to that of their parents

Sensitivity to Language Patterns • In addition to focusing on the speech sounds that are used in their native language, infants become increasingly sensitive to many of the numerous regularities in that language • Stress patterns: An element of prosody • Distributional properties: In any language, certain sounds are more likely to appear together than are others • Older infants are also sensitive to the minute pauses that occur between words in speech

Vocalizations • At around 6 to 8 weeks of age, infants begin producing drawn out vowel sounds • As the repertoire of sounds they can produce expands, infants become increasingly aware that their vocalizations elicit responses from others and they begin to engage in dialogues of reciprocal sounds with their parents

Babbling • Sometime between 6 and 10 months of age, infants begin to babble by repeating strings of sounds comprising a consonant followed by a vowel • A key component of the development of babbling is receiving feedback about the sounds one is producing • Congenitally deaf babies’ vocal babbling occurs late and is very limited, unless they are exposed to sign language, in which case they produce repetitions of hand movements that are components of ASL signs in a manner analogous to vocal babbling among hearing infants • As infants’ babbling becomes more varied, it conforms more to the sounds, rhythm, and intonation patterns of the language they hear daily

Word Production • Most infants produce their first words between 10-15months of age • First words typically include names for people, objects, and events from everyday life • The period of one-word utterances is referred to as the holophrastic period, because the child typically expresses a “whole phrase” with a single word • Overextension, using a given word in a broader context than is appropriate, represents an effort to communicate despite a limited vocabulary

Language Achievement • On average, American children say their first word at around 13 months, experience a vocabulary spurt at around 19 months, and begin to produce simple sentences at around 24 months • However, there is great variability in when different children achieve each of these milestones

Vocabulary • A spurt in vocabulary growth typically occurs at around 19 months, although there is great variability. • The rate of vocabulary development is influenced by the sheer amount of talk that they hear • Caregivers play an important role in word learning by placing stress on new words and saying them in the final position in a sentence, by labeling objects that are already in the child’s attention, and by playing naming games • Repeating words also helps children acquire them

Creating Sentences • Most children begin to combine words into simple sentences by the end of their second year • Children’s first sentences are two-word utterances that have been described as telegraphic speech because nonessential elements are missing • Word order is preserved in early sentences, indicating children’s understanding of syntax • Once children are capable of producing four-word sentences, generally at around 2½ years of age, they begin to produce sentences containing more than one clause

Length of Utterance

Learning Grammar • The strongest support for the idea that young children are learning grammatical rules comes from their production of word endings • Further evidence is provided by overregularization, speech errors in which children treat irregular forms of words as if they were regular • Parents play a role in children’s grammatical development by modeling correct grammar and expanding incomplete utterances • However, parents are more likely to correct factually inaccurate statements than grammatically incorrect ones

Theories 1. Behaviorist Theory • Skinner (1957) • Language is learned • language is acquired by conditioning and reinforcement • listening and responding to input is sufficient

Problems with this account • 1. We learn the rule of language: • e.g. cat -> cats, • wug -> wugs • break -> breaked (overregularisation) • 2. ‘Poverty of the Stimulus’ • 3. No Negative Evidence

Theories 2: Nativism • Maintains that using a language requires a set of highly abstract, unconscious rules – a universal grammar that is innate and common to all languages • Argues that the cognitive abilities that support language development are highly specific to language • A very strong statement of this assumption, the modularity hypothesis, proposes that the human brain contains an innate, self-contained language module that is separate from other aspects of cognitive functioning

Theories 2: Nativism • Evidence for this position is provided by the universal and species-specific nature of language, and by observations of invented sign language among groups of deaf children that imposes grammatical structure onto simple signs • The approach is criticized for focusing almost exclusively on syntax and ignoring the communicative role of language

Problems with Nativism • 1. Why do we take so long to learn language if it is innate? • 2. What are the universal rules that allow us to learn so many different languages?

Theories 3: Constructivist Theories • Social Interactionalist Theory (e.g. Snow, 1977) • Language development is influenced by its communicative function • Infants and young children are sensitive to pragmatic cues and are able to use even quite subtle aspects of the social context to interpret utterances • Infant-Directed Talk / Child Directed Speech

Theories 3: Constructivist Theories • Distributional Learning Models (e.g. Braine, 1973) • children pay attention to patterns in the input • learn which words behave in the same way: • cat/dog/bird => cats/dogs/birds => ALL NOUNS • Problem - many possible patterns (Pinker, 1984) • Connectionist Models (e.g. Rumelhart & McClelland (1987)

Conclusion • Language is a complex skill learned by children • Sequence of acquisition seems stable • How it is learned is disputed: • 3 types of theory: • behaviorism • nativism • constructivism

2: Early Language Development