CD - Wild Children, Deaf Children and a critical period for language

CRITICAL PERIOD HYPOTHESIS
1. LENNEBERG - 1967 - humans can only learn language to full proficiency (native) if they learn it during the critical period, which begins in early infancy and ends with puberty.
  1. later on, the brain becomes set in its ways and primary, basic skills not acquired by that time usually remain deficient for life.
    1. two ways of studying. 1. keep quality and quantity of experience the same but vary time of development 2. vary duration of experience but keep the time of development the same.
2. SNOW - 1987 - LENNEBERG turned out to be wrong. language acquisition begins before birth, not at two years. the OFFSET of any critical period (when sensitivity starts to decline) must be more like 5 years not the early teens since basic grammar is in place by 5 years old.
3. ANIMAL RESEARCH
  1. HUBEL AND WIESEL - 1963 - the development of vision in kittens. kittens were deprived of normal visual experience through closing the right eye. they varied either the age at which deprivation occurred or the duration of deprivation. the eye was later reopened and changes measured. FOUND if the eye is closed for the first 10-12 weeks after birth then it renders the kitten blind even when reopened. when the eye was closed as an adult even when reopened months later, could see again
    1. 1. period of peak plasticity when the system is especially open to experience. 2. cut off point beyond which plasticity is greatly reduced.
4. LINGUISTIC NATIVISM AND A CRITICAL PERIOD FOR GRAMMAR
  1. argue for a biological maturation. if the critical period is only for language, evidence against theories which argue that language can be learned through general cognitive learning mechanisms.
5. INNATE COGNITIVE MODULES
  1. CHOMSKY - 1980 - domain-specific (system constrained in terms of the range of info it can access). each module works independently and can be selectively impaired. has a particular neural structure / cortical area. may mature at different time scales.
THE EFFECTS OF LINGUISTIC DEPRIVATION
1. FERAL / WILD CHILDREN
  1. deliberately denied access to language. deprived of normal social contact and exposure to language.
    1. earliest report is the twins ROMULUS AND REMUS twin boys raised by wolves. remains a mystery what brings the nurturing side of these animals when they could eat the child.
      1. PROBLEMS WITH THESE AS CASE STUDIES - impossible to state the length of linguistic deprivation, no idea if cognitive faculties such as hearing, vision, intelligence and memory were normal. lack vital information
    2. these children avert human company and can endure extreme temperatures. they are known as HOMO FERUS - walked on all fours, hairy, were without speech
2. MISTREATED CHILDREN
  1. GENIE - 1970 - brought up in isolation, extreme deprivation and cruelty. kept in cages and tied to potty. she was found age 13. genie did understand a few words when found. she learned a number of words and became communicative. :) had basic word order but :( abnormal phonology ad had minimal morphology. lack of scientific rigour
    1. SCOVEL - 1988 - speaker-like accent is subject to its own critical period quite independent of any other aspect of language. our ability to acquire a flawless accent in a second language has lapsed by the age of five.
  2. BROWN - 1958 - notes the case of ISABELLE - found in the 1930s at age 6. her language learning was rapid. by 8 1/2 had caught up to her normal peers.
    1. OFFSET FOR THE CRITICAL PERIOD MAY BE MORE LIKE 5 YEARS than 13. OFFSET = point at which SENSITIVITY BEGINS TO WANE. TERMINUS = the very end of the line for a critical period. beyond the TERMINUS, first language learning should be IMPOSSIBLE.
3. DIFFERENT CRITICAL PERIODS FOR DIFFERENT ASPECTS OF LANGUAGE
  1. might be a different critical period for vocabulary than say grammar. the plasticity of genies world learning was greatly reduced to a typical toddler
  2. if language learning starts late then morphology suffers, e.g. two cup instead of two cups. a normal two year old will reach the two-word stage after learning 50 words. GENIE HOWEVER learned 200 before she made two-word utterances.
  3. TWO ASPECTS OF SYNTAX - function words and word order, function words (a, the, we, some). GENIE displays poor control over function words
    1. WORD ORDER - english is very specific - SUBJECT - VERB - OBJECT in that order. (SVO) e.g. mumma wash hair. GENIE's basic word order was correct. some aspects of syntax may be immune to to critical period effects or there may be multiple critical periods.
  4. GENIE was discovered at 13, which LENNEBERG says is the cut off point, so language learning should be impossible. however GENIE did produce some sounds
4. ARGUMENTS AGAINST THE EVIDENCE FROM WILD CHILDREN
  1. suffer emotional deprivation as well, lack of general cognitive stimulation, uncertainty as to IQ of child prior to isolation from input.
  2. mistreated children don't provide the basis for good science. precise PERIOD AND KIND OF deprivation is unknown. it is always assumed that these children had no exposure to language at all. COGNITIVE AND EMOTIONAL DEVELOPMENT are likely to be abnormal, so poor language development could be due to these and not necessarily language?
BRAIN LATERALISATION
1. LENNEBERG - 1967 - critical period for language ends with the completion of cortical lateralisation for brain functions after the brain has fully matured.
  1. LATERALISATION - left hemisphere of cerebral cortex is specialised for language - BROCA AND WERNICKE'S areas.
2. BRAIN PLASTICITY IN INFANCY AND CHILDHOOD
  1. brain damage to the language regions of the cortex in adults results in permanent language impairments but NOT in childhood.
    1. REILLY ET AL - 1998 - 3 to 5 year olds who had early brain lesions in the left hemisphere don't make more morphological errors than those who had one in right hemisphere (left hem is lang hem) by the age of 9 both groups performed as well as the normal control group
  2. THE RECEPTIVE BRAIN
    1. the existence of a critical or sensitive period is not dependent on the existence on this kind of cut-off. there is evidence that the child goes through a period of peak plasticity. the brain can be moulded according to the levels of input it receives. if the left hemipshere is removed as an adult there is permanent damage. if this is done before the age of two then language learning is still possible.
3. ARGUMENTS AGAINST THE LATERALISATION INTERPRETATION
  1. WITELSON ET AL - 1973 - lateralisation for language does not appear to coincide with Lenneberg's proposal for the end of the critical period for language.
  2. NEWMAN ET AL - 1986 - evidence that the brain is NOT fully plastic prior to this period
SECOND LANGUAGE LEARNING
1. JOHNSON AND NEWPORT - 1989 - looked at 46 people with KOREAN OR CHINESE as a first language. these people moved to the US at differing ages from 3 to 39. participants all had the same exposure to english (9 years) but early or late arrival varied.
  1. they judged sentences on 12 different aspects of morphology and syntax. such as pig / pigs. FOUND... the age of exposure affected every area of grammar tested, although some areas worse than others. English was native-like ONLY for those who arrived in the US BEFORE 7 YEARS OLD.
    1. IT is the CONTROL in applying rules that is affected by early vs. late arrival, not acquiring grammar itself. there is therefore a CRITICAL PERIOD FOR THE DEVELOPMENT OF ABILITY TO PROCESS LANGUAGE.
2. HEMISPHERIC ORGANISATION IN SECOND LANGUAGE PROCESSING
  1. NEVILLE AND BAVELIER - 1999 - adults who were first exposed to their 2nd language between 1-3 years old show native-like left-hemisphere specialisation for grammatical processing.
3. ARGUMENTS AGAINST A CRITICAL PERIOD FOR GRAMMAR
  1. GRADUAL DECLINE rather than sharp cut off point, sensitive but not critical.
  2. some studies found no effect on grammar - FLEGE ET AL - 1999 - studied KOREAN, learning second language english. found performance on grammar test not related to initial age of exposure.
  3. effects of level of education - HAKUTA ET AL - 2003
  4. A CRITICAL PERIOD FOR GRAMMAR OR PHONOLOGY?
    1. certain aspects of language learning such as phonology are affected by age of initial exposure than other aspects such as word learning.
    2. KUHL ET AL - 2005 - The critical period for phonetics seems to be much earlier than that for grammar.
4. AGE EFFECTS MAY NOT BE DUE TO A CRITICAL PERIOD
  1. SOME LATE LEARNERS do seem to achieve native-like competence in a second language.
    1. there may be no sharp cut-off point in age-related decline.
  2. the end of the critical period should be marked by qualitative differences in the kinds of learning taht take place. the kind of learning that takes place in adulthood should be qualitatively different from the learning that takes place in childhood
    1. NEWPORT ET AL - 2001 - SUGGEST that ADULTS LEARN IN A DIFFERENT WAY TO CHILDREN. as sightings of native-like second language learners are extremely rare, although there are some people who do very well in their second language
5. LENNEBERG proposed a definite cut-off point, however some authors now suggest there is a gradual decline of our cognitive faculties which come to us all with increasing age. hearing, vision, problem solvung skills and memory all decline. so receptivity to language may remain strong but it is these that decline.
6. HAKUTA ET AL - 2003 - looked at two million spanish speakers and 30,000 chinese speakers who rated their own english ability. THEY FOUND no evidence for a cut-off point, but found an age-related decline. gradual decline with age. the better they were educated the better their english. however problems with this study as rate their english themselves.
DEAFNESS AND LATE LANGUAGE LEARNING
1. deaf children provide a testing ground because they often start life in a linguistic vacuum. early diagnosis goes hand in hand with enhanced language development. parents can only start learning sign language once their child has been diagnosed. hard for parent to learn a second language
2. some children access to sign language begins when they start school at 5, for others it is when they go to a specialised school at 11.CHELSEA, a deaf woman, didn't start learning sign language until her thirties. chelsea managed to acquire some items of vocabulary, but making grammatical sentences was beyond her.
  1. GRIMSHAW - 1998 - REPORTED THE CASE OF E.M. - who received little formal education before the age of 12. at 15 received hearing aids. and since E.M. performed at chance levels. E.M.s problem was not a lack of grammar but a lack of consistency in applying knowledge of grammar. control over rules not well developed.
    1. EARLY VS. LATE LEARNING OF AMERICAN SIGN LANGUAGE.
      1. NEWPORT AND SUPULLA - 1990 - looked at native signers, early signers (4-6 years) and late signers (12 years +). ON AVERAGE HAD ALL BEEN USING ASL for 30 years. FOUND - word order knowledge was okay. late learners were poorer on all tests pf morphology. native and early learners differed on some tests of morphology.
        IT HAS BEEN SHOWN THAT NATIVE AND LATE DEAF SIGNERS DIFFER IN TERMS OF BRAIN ORGANISATION. language is organised differently.
3. IMPLICATIONS FOR LINGUISTIC NATIVIST THEORIES.
  1. could tie in with linguistic nativist view which argue for biological maturation. PROBLEM - morphology worse affected than syntax.
    1. ALTERNATIVE VIEW OF THE CRITICAL PERIOD - NEWPORT - 1991 - the importance of starting small.
LANGUAGE CREATION BY CHILDREN - CREOLES
1. pidgin languages - semi languages used for communication between groups who speak different native languages. words are often taken from colonial language, e.g. english in hawaii. has little or no grammatical structure. the pidgin is not the native language of the speakers.
  1. CREOLE languages develop out of pidgin when the language is learnt as the first native language by a generation of children. WHERE DOES THE GRAMMAR IN CREOLES COME FROM? BICKERTON - innate grammatical knowledge which children have access to until puberty.
2. NEW SIGN LANGUAGES.
  1. deaf chinese and US english speaking children growing up in hearing and non signing households invented signs together with their parents to communicate. children's signing quickly acquired a grammatical structure which was unlike spoken english or mandarin, but was similar to deaf children in another community.
  2. SENGHAS ET AL - 2004 - before the 1970s deaf people in NICARAGUA had little contact, in 1979 deaf children were brought together. no one taught them to sign but as soon as they were together they developed a system of gestures to communicate. KNOWN AS NSL. today the most fluent signers are the youngest children. NSL is now evolved into a real language.
    1. CRITIQUE - POLICH - 2001 - NSL developed over many years and involved contact with established languages such as ASL and spanish. didn't suddenly develop. difference between the generations of signers due to the different kind of input they were exposed to
ARGUMENTS AGAINST THE CRITICAL PERIOD FOR GRAMMAR
1. wild children - emotional deprivation, lack of general cognitive stimulation. don't know original IQ. LATERALISATION OF LANGUAGE - not at end of the critical period. SLA AND ASL - gradual decline rather than sharp-cut off point "sensitive but not critical".... CREOLES AND NSL - ambiguities in true history. MORPHOLOGY WORSE AFFECTED THAN SYNTAX - so not a critical age for grammar.
  1. LINGUISTIC NATIVIST THEORIES - ties in with biological maturation, more general cognitive limitation helps language learning in early childhood, NEWPORT - 1991 - starting small.

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