6>Language development in deaf children & the critical period Flashcards
misconceptions about sign language>
-all sign lang is the same around the world
- sign lang has no grammar
- all deaf people can lipread
- deafness is genetic
- cochlear implants cure healing
- the best way for a deaf child to acquire spoken lang is to raise them WITHOUT sign lang
consequence of sign lang misconceptions>
> many deaf children (70%) are deprived of lang during the critical period in development
what does ‘language deprivation’ of deaf children lead to> (3)
> this ‘language’ deprivation leads to:
(1) lack of strong lang skills (in sign/spoken)
(2) delays in cognitive development, social development, school readiness (i.e. lang learning & others perspectives)
(3) difficulties with literacy & numeracy skills
critical period hypothesis=
language needs to be acquired before puberty, as this is the CRITICAL time for lang acquisiton
critical period from U-B>
> due to matural changes in the brain (lateralization)
lateralisation= brain organising itself into>2 hemispheres
& lang in end being processed in left hemisphere (in L handed people=more balanced)
critical period from G-N>
maturation of ‘innate language module’
- needs to be stimulated up until puberty
- if not stimulated by an linguistic input then cant be learnt any longer
Alternative explanation to language critical period>
early neural plasticity
alternative to ‘critical period’> early neural plasticity>
-children are generally better at learning new things
- children’s brains are more flexible than adult brains & can recognise when damaged
- brain damages studies show children can recover from trauma that would cause ‘aphasia’ in adults (as can remodel brains & use different areas to deal with lang processing)
Problem with using feral children as evidence for crit period>
- feral children are vary rare
- written records may not be accurate
Genie: context (5)
- locked away 11 years
- hardly any exposure to human lang
- hardly any social interaction
- no physical or visual stimulation
- discovered by social services aged 14
Genie> lang development after 1 year of learning>
- looked promising (similar to 18-20 month)
- developed some knowledge of grammar> distinguished singular/plural nouns
- produced 2-word & some 3-word utterances
Genie: what happened after 1 year point>
- plateaued development
- speech as similar to ‘telegraphic speech’
- struggled with possessives, negation, prepositions & more
Genie: after 5 years> (3)
- couldn’t use negation
- couldn’t produce WH-qns correctly (“i where is graham cracker on top shelf?”)
- confused pronouns “you” and “me” (<indicates some perspective taking problems)
problems with ‘Genie’ research>
- evidence appears to be selectively used
- other deprived input is not taken into account (not just ling that was deprived> also socialisation, physical & visual stimuli)
Isabelle: context>
- raised alone by deaf-and-mute mother in 1930s
- discovered age 6 (BEFORE puberty)
- no evidence of active abuse
isabelle: lang learning after 2 years>
- had vocabulary of 2000 words after 2 years
- could use complex grammar
- more promising lang development than genie
what caused the difference in isabelle vs genie’s lang learning> (CRIT period explanation)
- age when found (before/after puberty)
what caused the difference in isabelle vs genie’s lang learning> other explanations>
- genie found to have brain abnormalities (could have had prior & contributed)
- psychological factors>abuse
- lack of social interaction for genie, some for isabelle
- selection & interpretation of data
what do hearing parents with deaf children often do>
- expect children to lip read (& only used spoken lang around)
- try to get cochlear implants (as believe can ‘cure’ them)
features of sign language>general
- prosodic, phonological, morphological & syntactic structure
- greater degree of iconicity than spoken lang
prosodic, phonological, morphological & syntactic structure of sign language>
> each element (hand shape, orientation, location, movement) can be articulated in multiple ways (similar to phonemes)
facial expression & upper body position expresses phonology
different morphemes can be expressed simultaneously (i.e. motion for verb, hand shape & orientation for noun)
iconicity in sign lang>
- Greater degree of iconicity than in spoken lang (can be fairly straightforward link between the form & meaning of the sign
- but ASL & BSL are mutually unintelligible
- some signs do not have iconicity
acquisition of sign languages>
- same milestones & time course as in spoken lang (manual babbling> first words> word combinations)
- manual babbling produced by children exposed to ASL can be distinguished from hand movements produced by (hearing) children exposed to English
- only sign-exposed babies produce low frequency hand movements in the area in front of the body
comparison of ‘native signers’ to ‘late signers’> (6)
- age of acquisition has a greater effect on fluency in production & comprehension than years of exposure
- native signers outperform late signers (especially in grammaticality judgement tasks)
- early exposure to sign also gives an advantage for learning a spoken lang
- native signers are better at learning to read & write
- native signing deaf children often become fluent bilingual in both a sign & spoken lang (where late signers fail)
- native signers show advanced social-cognitive skills compared to non-native
what do cochlear implants do?
- provide a partial sense of hearing to deaf individuals who have a functioning AUDITORY nerve
- neural impulses are created & are perceived as sounds
when cochlear implants were developed in the 80s:
- they worked best for adults who had acquired and LOST a spoken lang
- but not for adults who never learned a spoken lang
- young children who received a CI in the 90s were also able to learn a spoken lang
Cochlea implants today>
- usually implanted before 1st birthday
- the earlier the CIs are implanted, the better the outcome
- children implanted at 12;0+ tend to have very limited success
limitations of cochlea implants>
- do not guarantee 1st lang acquisition
- many children who were born deaf/become deaf in first few years of life experience little to no success in lang acquisition with a CI & turn to sign lang AFTER crit period (^thus run risk of completely acquiring neither)
cochlear implants (& native ASL) vs bilingual codas study>
- compared deaf children with CIS & exposure to ASL from deaf parents with bilingual (ASL/spoken eng) hearing children born to deaf parents
- no difference between groups
- thus exposure to sign does not weaken effect of CIs
