child language summary note

7/28/2019 Child Language Summary Note

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Lecture 2 The Human Brain and LanguageLanguage Disorders

Brocas aphasia: Difficulty in language production.Telegraphic speech missing function words(articles and prepositions), only content words canbe produced. Intact comprehensive ability =>Showing that production and comprehension ofspeech are separated.Wernickes aphasia: Difficulty in language

comprehension. Fluent but meaningless speech.Conduction aphasia: Unable to repeat. Fail toconnect the Wernickes area and Brocas area.Language LateralizationHypothesis 1: The left hemisphere is notspecialized for language at birth. Instead, bothhemispheres have equal potential for languageacquisition.-> Biologically the brain has the plasticitynecessary for language learning before the critical

period. After that, the brain plasticity is lost.Hypothesis 2: The left hemisphere has the adultspecialization for language from birth; nothingabout lateralization changes with development.(Languages are localized to the left hemisphere)Brain Development of ChildrenDehaene team To examine the functionalorganization of brain activity in 3-month-oldinfatns when they were listening to speech.fMRI: can study which part of the brain is moreactive during some particular processes (check

which part consumes more oxygen)Benefits - noninvasive; using magnetic basedtechnologies to image as opposed to radioactivebased is that there is no limit to the number ofscans that can be performed.Drawbacksis more subject to motion artifact (ifsubjects head moves, the images will becomeblurred, thus hard to get images from children).Scanner noise makes it difficult to use auditorypresentation.Experiments result: Left lateralized brain regions

similar to those of adults, including the superiortemporal and angular gyri, were already active ininfants (which support the second hypothesis)Perspectives of Language Development

Nature vs Nurture: The relative importance of anindividuals innate qualities and experience.Nature: genertic, heritable: traits determinedmainly by genetic factors (e.g. blood type, eyecolour)Nurture: environment / social effects: traitsdetermined mostly by environmental factors (e.g.

language use, religious practiced)Competence versus PerformanceCompetence: The actual capacity / potential thata person has; the knowledge of ones language;

inner knowledge of linguistic rules (used mainly tocheck grammaticality)Performance: The actual use if language inconcrete situations; the expression of linguisticrules in every usage (susceptible to performancemistakes).Structuralism versus FunctionalismStructural description: Analyze the structure /syntax of utterance produced. (focus on grammar)

Funtional description: Analyze the social contextin which an utterance is produced; consequenceof the utterance; pragmatic and social use oflanguage (syntactic form is ignored) focus onsocial circumstances, e.g. where and when did thechild produce the utterances? Why did he produceit?Behavourist ViewFocus on language performance - observable andmeasurable aspects of language behaviour;

believe that language skill is not different from anyother behaviours; change in behvaiours occurs inrespond to the consequences of prior behaviour;external reinforcement motivates languageproduction. => reinforcement of appropriategrammar and language leads to a childsacquisition of language and grammar (Wronggrammar => negative reinforcement likepunishment or ignorant).- Language acquisition is a function of external

environment and shaping

- Infants learn language through the monitoringand management of reward contingencies- No innate device and information is required- Children were born as blank states- They learn language through via shaping the

sounds they hear from their caregivers intowords and eventually sentences throughselective reinforcement.

Classical Conditioningtraining of animals(correlate one thing with another) [First

unconditioned stimulus, unconditioned response,then combine unnatural stimulus and naturalstimulus to trigger out conditioned response.];Operant Conditioning Give reward to animals,then they will repeat the action in order to get thereward; imitation These are useful for animal training; shaping

childrens desirable behaviours; behaviourtherapy (e.g. electric chocks pair with a targetbehaviour / word causes negative feelingstowards that behaviour / word); teaching

mentally retarded and autistic children learn tospeak through careful application of shapingand reinforcement.


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Supporting Evidence: Mothers who are moreresponsive to their childrens verbal behaviourtypically have children who show more rapidlanguage growth; Conditioning processes mayalter the meanings of words, e.g. electric shockspair with words causes negative feelings towardsthe words.Contrasting Evidence: Children are not carefullyshaped and tutored in natural home environment.

Parentsfeedback on childs utterances is notalways based on grammaticality (will also bebased on meaning or content), e.g. they say yesto an ungrammatical sentence with correctinformation (how do they develop grammaticality?).Children are also resistant to changes (maturationdetermines language acquisition?). Definition ofreinforcement is problematic, and it cannot bemeasured.Criticisms: Noam Chomsky the claim of

acquiring and maintaining verbal behavioursthrough reinforcement is quite empty, as it has noclear content in reinforcement only as a coverterm for any facto, detectable or not, related toacquisition or maintenance of verbal behaviour;this grammar is of an extremely complex andabstract character, and that the young child hassucceeded in carrying out a remarkable type oftheory construction => This suggests that humanbeings are somehow specifically designed to dothis.

The nativist view

Chomsky: Language learning is not reallysomething child does; it is something that happensto the child placed in an appropriate environment,much as the child body grows and matures in apredetermined way (about genetic build-up) whenprovided with appropriate nutrition andenvironmental stimulation (cannot change yourlanguage behaviors => just like daily supplements

cannot affect your eye colours)Steven Pinker: Language is an instinct. It is notlearnt but determined by a biological basis.The development of language is more like thedevelopment of an organ (heart, liver) than thedevelopment of a skill (throwing a ball)Language development follows its own schedule.=> The language instinctUtterances produced by parents are ambiguous.- Children are able to construct their own

syntactic rules based on utterances from

examples in life. But they may fail to realize thegrammatical mistakes

- The child needs to hear about 25 differentkinds of noun phrases and learn nouns one by

one, and would be able to produce millions ofsentences automatically.

Poverty of stimulus there was not sufficientlanguage input to children in their environment.If children had to learn all the combinationsseparately, they would need to hear about 140million different sentences => Thus it is impossibleto learn from environment. Language ability must rely on innate abilities or

structures Language development is more like maturation

than like learning something. The environment merely triggers the

maturation of the faculty of language. It doesnot shape or train verbal behaviour (just likebabies and nutrients to grow healthily)

Nativist mainly focuses on language competence(actual knowledge / ability) -> Languagedevelopment is a result of human nature

Some inner device in the human infant to acquire

language a language faculty [LAD LanguageAcquisition Device] (a component of the braindevoted to language) => Children developlanguage rapidly, effortless and without directlyinstruction or imitationChomsky: The human capacity for language is adevice residing in the human brain that takes asits input certain information from the environmentand produces as its output the ability to speak andunderstand a language.

The initial state of language faculty is determinedgenetically and similar across human species.The initial state of language faculty: containsgrammatical rules and linguistic categoriescommon to all the worlds languages (UniversalGrammar, UG). [Parameters are not restricted tospecific languages (so a French may learnChinese innately). Learning a new language is justadjusting the parameters]Evidence: (1) The phenomenon ofovergeneralization children are rule learners.

(e.g. go -> goed) (2) Similar rule uses at about thesame time across cultures. (3) The infants brainsresponded asymmetrically to speech versusnonspeech [they use the left hemisphere whenhearing speech, right hemisphere when hearingnonspeech -> they can distinguish speech or non-speech] (4) A critical period for language learning[Lack of early development leads to inability topick up language normally]Studies by Goldin-Meadow and colleagues: 10deaf children born to hearing parents elected not

to sign with their children but to teach themspoken language (failure) -> loving environmentwithout language input.


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These children were found to produce differenttypes of gestures that were similar to signs of signlanguages to communicate with others [even ifchildren are not taught, they are able to developtheir own communicative tool]Criticisms: (1) Bohannon and Stanowicz: Adultsdid provide grammaticality feedback to childrensutterances. -> If children produce well-formedspeech, adults would imtate their speech

immediately; If children produce language errors,adults would recast or expand their speech. Once children have received a corrective

recast, they are more likely to repeat thegrammatical sentence later [so environmentdoes play a role]

Moerk: corrections do indeed play a role. From hisresearch, corrections are not only abundant butcontingent on the mistakes of the child.(2) Passive exposure to language does not

produce normal language skills (watching TV).Sachs, Bard, Johnson: Let some listening children(with deaf parents) expose to spoken English onlyby watching TV => The oldest child had littleproductive speech, severe articulation problem,and no syntax. After interacting with native Englishspeakers and with the help of speech therapists,the child could soon learn to speak normallyThe Interactionist view

Language development is an interaction of theinnate features of the mind and childrens

language learning experiences.There is some innate device that allows childrento develop language based on experience (but thedevice may not be specific to language)Emphasize on the importance of interactionbetween the mental skills and environment.3 Approaches1. Jean Piagets Cognitive Approach

(Constructivism)

Language development is a result of thecontinuing interaction between the child current

level of cognitive functioning and environment(linguistic and nonlinguistic)Cognitive development determines languagedevelopment [learn the symbols (signifier)]From birth to 24-months of age: the period ofsensorimotor intelligence. Children have not yetreceived object performance during this stage:Out of sight, out of mind [due to a lack ofsufficient memory memory working capacity]Children have to achieve object performancebefore they could use symbols to represent

objects. When children can perceive semanticrelations among objects and people in the world,they will start producing word combination thatdepict these relations. (e.g. Knowing that animate

beings act upon inanimate objects -> Start usingword combinations with SVO sequence)Evidence: (1) The occurrence of the vocabularyspurt (a sudden rapid gain in vocabulary) and theappearance of two-word combinations coincide inmost children with their attainment of the laststage of sensorimotor development.(2) Children are not able to use past-tensemorphemes until they have grasped the concept

of past [Have to know what happened before]Criticism: (1) Co-occurrence is not equivalent tocausality [does not have cause-and-effect, sincehuman IQs may not be manipulated](2) Child learn to sign from their deaf parents longbefore they achieve full object permanence. [theycan sign before speaking, may due to the limit ofvocal system development](3) Language and cognitive skills may beseparable. Semantics and cognitive development

are parallel, but syntax and morphology are quitedifferent.2. The Information Processing ApproachA mechanism that encodes, interprets, operates,stores information from the environment andretrieves information from the memory. [Imitate theneuron units, each unit represent a feature oflanguage; think of different features of words likelength, shape] Language is no different from anyother information.The Connectionist Model

[The nodes become stronger when morefrequently used.]

[a feature of aletter is brokeninto very smallunits (strokes);familiarity /frequencyeffect: when

exposed to the same word the second time, faster

response is achieved]Nativist versus Interactionist: (1)Piaget saw thehuman child and his mind as an active,constructive agent that slowly inches forward in aperceptual bootstrap operation; Chomsky view themind as a set of essentially preprogrammed units,each equipped from the first to realize its fullcomplement of rules and needing only the mostmodest environmental trigger to exhibit itsintellectual wares.(2) Scientists in general agree that there must be

an internal faculty of the human mind for languageacquisition, but they disagree about the nature of it.


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Species specific versus Non-species specific(language acquisition is also possible to otheranimals)

Domain specificity (knowledge of language isinnate) versus Domain Universality / general(cognitive skills for language acquisition alsoresponsible for other processinginteractionists belief)

Domain specific theory

It assumes that the internal contribution tolanguage is domain-specific. The human mind haslanguage-specific module, besides other modulesuch as the number module, the perceptionmodule, etc. Information from other modulescannot be used to help the language module. (Themodularity thesis) -> It dismisses the concept of ageneral mental ability.Domain general theory

It supposes that it is domain-general cognitive

skills that contribute to language acquisition. Thisdomain-general faculty also contributes to thedevelopment of many other human behaviours.Empirical Evidence: Markson and Bloom:Investigate whether fast mapping (the ability tolearn aspects of the meaning of new words on thebasis of only a few incidental exposures and canretain knowledge for a long period [Lean quick,remember for long]) is limited to word learning ornot.Experiment: Subjects exposed to 10 kinds of

objects, 4 familiar and 6 unfamiliar. They wereasked to use some of the objects to measureother objects.- A new word koba was used to refer to one of

the six unfamiliar kind of objects [give thename]

- They were also told a new fact about objects ofanother kind [give the fact]

- They were tested for comprehension(i) immediately after the training;(ii) 6-8 days later(iii) 1 month later

Results: [learning mechanisms apply to bothinformation and language (i.e. fast-mapping forinformation processing)]Their findings reveal that subjects were equallygood at remembering which novel object wasgiven to the experimenter by her uncle, suggestingfast mapping is not special to word learning.Infants as statistical learners

Word segmentation: How do infants segmentfluent speech into words?

One important source of information that candefine word boundaries in any natural language isthe statistical information contained in sequence ofwords

The transitional probability from one sound to thenext will generally be highest when the twosounds follow one another within a word, whereastransitional probabilities spanning a wordboundary will be relatively low.Transitional probability is one sort of statisticalinformation.(e.g. pretty#baby, the transitional probability frompre to ty is greater than that from ty to ba)

Experiment: 24 8-month old infants listened tocontinuous stream of 3-syllable nonsense wordsfor 2 minutes. Four nonsense words wererepeated in random order for two minutes.The transitional probabilities between syllablepairs within words is 100%, while between wordswill be about 33%.Results: Infants spent more time listening to thenovel stimuli (nonword strings) compared tofamiliar ones (word string)

This suggests that 8-month-old infants coulddetect the transitional probability and used it tosegment word boundaries. The babies were capable of statistical learning.Infants as rule learners

Rule learning by 7-month-old infantsAlgebraic rules: Open-ended abstractrelationships for which we can substitute arbitraryitems.e.g. Correct sentence = plural noun phrase + verbphrase with plural argument => The three little

kitties + lost their mittens.Experiment: 16 7-month-old infants randomlyassigned to either an ABA (ga ti ga) condition oran ABB (la li li) condition. They heard sequencesof syllables for 2 minutes. In the test session, thebabies heard sequences of entirely new syllablesthat either matched the pattern they heard ormatched the other pattern.Results: Listening time to sequence of new soundpatterns was much longer than the listening timeto familiar ones. The finding indicates that 7-

month-old infants were capable of learning soundclustering rules. => Infants possess at least twolearning mechanisms: rule learning and statisticallearning.Statistical learning (central to the nativist view)or rule learning?

Language acquisition depends on the ability tolearn rules. Linguist knowledge consists of asystem of rules that operate over symbols. Oncewe learn the rules, we would be able to apply therules to form new sentences.

The connectionist view dismisses the importanceof rule learning: They emphasize on theimportance of statistical mapping, weight settings.3. Social Interaction Approach


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Emphasizes the mothers roleMotherese: (or child-directed speech, CDS): themothers unusual vocal behaviour when talking toher baby.Motherese helps children to:- segment the sound stream appropriately;- produce sounds by watching their mother

produce the exaggerated sounds;- understand turn taking [social communicative

behaviour]Some early language may be taught by theparents and children learn through rote or imitation.For example, children learn the social use oflanguage through parents- Important for learning vocabularies- May also help children acquire mature form of

utterancesSupporting Evidence:

- Infants prefer listening to child-directedspeech; infants prefer listening to their mothersCDS over other mothers CDS; Children maycontrol the speech addressed to them ifadults produce long complex sentences thatchildren cannot understand, they will signalsuch failures and the adults will tend to shortenand simply their utterances.

- Neglected children scored much lower in themeasures of language comprehension thanother maltreated children or control-groupchildren [exposure to languages drop, drop in

rate in language acquisition]The neglected children were 6 9 monthsdelayed in language development.; Childrenwho were abused and neglected were 4 8months delayed; Children who were abusedbut not neglected were 0 2 months delayed.

Contrary Evidence:

[There are places where CDS does not exist, butstill children can acquire language well; it touchesmore on the vocabulary aspects]The complexity of CDS was unrelated to the

childrens language gains [although it can attractinfants attention, it cannot account for childrenslanguage competence].Problems in making conclusions based on thecorrelational studies [Nativist argues more forgrammar; Nurturist argues more for vocabulary,phonological development]Critical Period Hypothesis (CPH)

Certain behaviour is developed more quicklywithin a critical period than outside it. This periodis biologically determined. For language

development, a biologically determined periodexists during which language acquisition mustoccur, if it is to occur at all. This sensitive periodis termed the critical period.

ExamplesImprinting some birds walk as soon as theyhatch. Chicks or ducklings will follow the firstmoving thing they view, and they will follow itforever. Normally, the 1st thing a baby chick seeswhen it hatches is its mother. As a result, the chickfollows its mother everywhere. When this occurs,the chick is said to be imprinted on its mother.Imprinting cannot happen any time. It must occur

within hours after hatching.Human examples: Some cells in the brainrespond input from both eyes in normal adults.If these cells fail to receive input from two eyesduring the 1st year of life, they lost this capacity. [Ifinfants eyes are covered for years (due to injury),they will lose the ability to see. => adequate visualinput is required]Features of critical period

Some environmental input is necessary for normal

development, but biology determines when theorganism is responsive to that input.The period of responsibility is the critical period.Lenneberg: It assumes that language acquisitionmust occur before the onset of some period [theycannot learn the grammar normally after thecritical period]Wild or abused children [not ethical to alter

childrens surrounding environment]The wild boy Victor: He was 12 years old whenfound [no language exposure at early age]. He

had been living wild in the woods in France. Hewas capable of making sounds but had nolanguage.He was placed at the National Institute for Deaf-Mutes in Paris for training.The boy was able to learn some sociallyappropriate behaviours, but he never learnt morethan a few words.The case of Genie: Genie grew up in LosAngeles. From the time she was 20 months olduntil her discovery at the age of 13, she spent her

time alone, strapped to a potty chair in a smallbedroom. She was fed hurriedly, with minimalinteraction and no talk. If Genie made any noise,her father would bear her with a large piece ofwood. She had no language when she wasdiscovered.- At 13 years old (when she was first

discovered)She did not talk at all.

- At 17 years old (after she had got 4 yearstraining)

Her language age was about 5 years old onvocabulary tests. She combined words intocomplex sentences and could expressmeanings. Vocabulary skills were much better


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than syntactic skills. Her grammar wasdeficient in both production andcomprehension. [Meanings were expressedungrammatically]

Genies brain activity in language processingThe right hemisphere was responsible for Genieslanguage (listening skills). The left hemisphere,which is relevant to normal language userslanguage functioning, was not involved in Genies

language processing. -> Suggest that by age 13,the left hemisphere that has never been used forlanguage has lost that capacity. [Dont knowwhether the abnormal brain activities cause thelanguage deficiencies (or due to mentalretardation)]The case of IsabelleFound in the 1930s at 6-year-old (The child wasfound at the critical period). She lived in a darkroom with only the deaf-mute mother for contact

[no exposure to language].She was trained intensively to speak, and she didlearn to talk. [Rather normally]It was documented that she had normal IQ andlanguage skills at age 8.Late Acquisition of American Sign Language

(ASL)

Many children born deaf to hearing parents. Theyhave no language input at home because theycould not hear, and their parents do not know signlanguage.

They exposed to sign language later.Newport: studied three groups of adults:Acquired ASL as infants, between 4 6, after 12.[parents learn ASL and teach / interact with thechildren]He tested the grammar of ASL. Adults whoacquired ASL after 12 did not perform as wel asthose who acquired ASL since infants.Early learners of sign had an advantage over latelearners in recalling and reproducing ASLsentences that were presented to them. [Some

people can still acquire languages after the criticalperiod]Second Language Development

Early bilinguals (before age of 6) as good asnative speakersLate bilinguals (after age 12) accent(phonology) and syntax are not as good as nativespeakers [There is at least a sensitive periodwhich lets humans acquire language more easily]Evidence: Johnson and Newport

Participants were native Chinese / Korean

speakers, manipulated age of arrival in the U.S.Task: listened to sentences and judge whether ornot they are grammatically correct (grammaticalityjudgment)

Gradual declining relationship between languageproficiency and ages[Problem: why not a sudden drop if critical periodis present?]Is there a biologically defined window during whichlanguage acquisition must occur? If so, when willlanguage acquisition be automatically shut off?Lenneberg: end after puberty.

Bates: capacity for recovering from aphasiabegins to decline after age 5. [chance for recoverydrops after 5 years old]Newport: A continuous drop in second languageproficiency from age 6 to adults; but notdiscontinuity of language proficiency is produced.Patricia Kuhl: 6-month-old infants can detectphonetic changes in both native and nonnativecontrasts, 12-month-old infants can only detectsuch changes in native contrasts; Japanese nativespeakers, even after training, have difficulty of the

/r-l/ distinction. [Two different phonemes ofChinese => even infants in other languages canrecognize them; After acquiring the nativelanguage, the flexibility in language learning drops,but ability to recognize phonemes in the nativelanguage increases]There is no doubt that children can learn languagemore naturally and efficiently than adults, aparadox given adults superior cognitive skills.[The language system has adopted the nativelanguage]

Neural commitment to a learnt structure mayinterfere with the processing of information thatdoes not conform to the learnt pattern. On thisaccount, initial learning can alter future learningindependent of a society time period.The critical period for language learning dependson experience, not just time.[If second language is similar to the nativelanguage, the difficulty acquiring the secondlanguage will drop.]What we argue for is, there is a biologicalpreparedness for language acquisition that ismaximal in early childhood.

200

215

230

245

260

275

native 3--7 8--10 11--15 17--39

Age of Arrival

mean score

Second

language

proficiency


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Language acquisition also depends on otherfactors, including general cognitive processes,social environment and motivation.The benefit of these other factors typically declinemore gradually than the biological advantage andare more variable after puberty.Phonological Development

Phonological perception: how children receivespeech sounds receptive language

Phonological production: how children producespeech sounds productive languagePrelinguistic Speech Perception

Newborn: Prefers mothers voice to a stranger[because they were able to hear mothers voicesbefore birth]3 7 months: Respond differently to differentintonations [different emotions]8 12 months: some understanding of simplewords (no, yes)

The auditory system is functioning in the fetuseven before birth.Fetuses remember their mothers voice and showa preference for their mothers voice after birth.Measurements of the infants perceptualabilities

3 characteristics of babies:Babies like to hear sounds; Babies lose interest ina sound when it is presented repeatedly; Babieswho have lost interest in a previously presentedsound will become interested if a new sound is

presented.High amplitude sucking (HAS): An experimentalprocedure used to test if infants perceive twosounds as different.- Used with infants after 4 5 months old.- Infants are given a pacifier to suck on that is

connected to a sound generating system.- Each suck causes a sound to be generated.- When infants show habituation to one sound

[when they get bored] (slower sucking rate), anew sound will be generated.

- If infants show dishabituation to a new sound(suck faster), we may infer that they coulddiscriminate the sound change.

Limitations: 1. If the baby does not increase hersucking rate, it is uncertain if the baby was unableto make the discrimination or was justuninterested in the new sound.2. Doesnt work well with babies older than 4 5months.Head turn technique: An experimental procedureused to test if infants perceive two sounds as

different.- Used with infants between 5 and 12 months

old.

- Infants are trained to move their heads whenthey hear a change in a sound being presented.

1. A sound is played over and over and then thesound is changed, followed by activation of ahidden moving toy. [to classical conditioning,habituation stage]

2. The babies turn to look at the toy when it isactivated.

3. After several trials, when the sound beingpresented changes, the babies turn their headstoward the place where the toy will appeareven before it is activated.

Infants are capable of discriminating minimal pairs[differ only in one phonetic feature, little different insounds]Infants are able to discriminate contrasts not usedin their own language.Categorical Perception (CP) [perceptual ability todifferentiate categories, may be colours]: When

people listened to sounds that vary along anacoustic continuum, they hear them categorically.The difference between /b/ and /p/ is in theduration of the time lag (voice onset time, VOT)between air passing through the lips and the vocalcords vibrating when producing a syllable.- Sounds are created artificially that vary along

this VOT continuum- When these sounds are played to adults, they

perceived sounds with VOT less than 25 ms as/b/ and those with a VOT of more than 40 ms

as /p/.Categorical perception is taken as an evidencethat speech perception is special.Why CP is important in language development?A phoneme: a set of non-identical sounds thatvary on the speakers, contexts, etc.Infants have to learn to categorize sounds withdifferent acoustic features into the same category.Computers are unable to categorize sounds in thisway.

Where do we perceive speech categorically?The motor theory of speech perception [Weperceive because we produce that way]- Speech perception is influenced by speech

production- We produce /ba/ and /da/, but nothing in

between; thus we perceive /ba/ and /da/,nothing in between.

- Categorical perception is a result of learning toproduce speech

[Impossible for infants to show categorical

perception because infants perceive soundsearlier than producing sounds]Eimas et. al: using the HAS procedure- 1- and 4-month-old infants


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- 3 conditions:Listen to a 20-ms VOT sound and then a 40-ms VOT sound

Listened to a 60-ms VOT sound and then a80-ms VOT sound [except same as controlcondition (CRUCIAL: If infants and adultsperceive sounds in the same way) since adultstudies show there are no differences]

-> If infants perceive sounds based onacoustic properties, infants can differentiatethe differences

Listened to a same sound (control condition)

[Result shows that they do not perceive twosounds differently.]Infants are capable of categorical perception.Language taps specific human capacities andhumans have evolved mechanisms thatspecifically serve this ability.Categorical perception is not domain specific- Innate sensitivity hypothesis: we are more

sensitive towards some physical attributes [e.g.boundaries between words] (prototypes;boundary; boundary effect)

- Label learning hypothesis: we learn labels,names of labels / categories affect ourperception

- CP is also found in nonspeech domain, suchas musical tones, colour perception, and facialidentification.

- CP is also found in non-speech sounds thatmimic the acoustic properties of speech

- Not all speech sounds show CPCP are more commonly found in consonantsthan in vowels.Among consonants, liquid, semi-vowels, andfricatives are less categorically perceived thanstops

CP is NOT species specific- Other animals, like chinchillas and monkeys,

also perceive VOT categorically.CP is not speech-specific, and could be influencedby learningCheour et. al.: Newborns cam be taught todiscriminate between similar vowel soundsMethod: Recorded electrophysiological brainresponses of newborns as indexed by mismatch

negativity (MMN), which is elicited by infrequentdiscriminate changes in auditory stimuli. Cheourwanted to see responses of sleeping newborns tothe vowel sounds /y/, /i/ and /y/i/Subjects: Experimental group; two control groupsProcedure: All groups had 2 MMN recordingsessions, 1 in the evening and session 2 in thenext morning. Each MMN session lasted for < 1hour. [whether they can learn new sounds while

asleep]Experimental group: received auditory training ofover 2.5-5 hours between session 1 and 2.Control group 1: no trainingControl group 2: received auditory training with/a/ & /e/ [use this control group since it can reducethe self-fulfilling prophecy induced]Conclusions: Experimental subjects learnt todiscriminate both deviants from the standard aftertraining. For this group, the MMN elicited by /y/i/

was not significantly different in session 1 but itwas in session 2.Linguistic sounds can be learnt by newborns.Newborns can differentiate between their nativelanguage and an unfamiliar language.Mehler et. al: A 4-day-old infants born to French-speaking mothers showed more arousal whenthey heard French than when they heard Russian.Babies of mothers who spoke a language otherthan French or Russian showed no difference inarousal to French or Russian.

Werker and Tees: 6- and 8- month-old English-learning infants could discriminate betweenconsonant contrasts of unfamiliar languages. 10-to 12- month-old infants lost this ability.[When infants develop their native languages, theywill filter out the sounds that they dont need.]The decline of perceptual abilities occurs atdifferent ages for different types of contrasts:- The ability to perceive non-native vowel

differences decline from 6 to 8 months.- The ability to perceive non-native consonants

differences decline at or after 10 to 12 months. Does not mean that infants fail to perceive

differences among all non-native contrasts;they only fail to perceive differences of thoseforeign sounds that are phonetically similar tosounds of the native language. [If notcontrastive in native language => graduallylose ability to differentiate]

At what point in development does linguisticexperience alter speech perception?Kuhl et al.: 6-month-old infants, 32 in USA, and 32

in SwedenTest infants sensitivity to two vowels: /i/ (English),/y/ (Swedish)

VOT=20 VOT=40 VOT=60 VOT=80 No Change


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Findings: Swedish infants were better incategorizing /y/, while American infants werebetter in categorizing /i/. [CP can be affected byexperience]Newborns are sensitive to repetition sequence(Gervain et. al)22 newborns listened to syllable sequences (withrepetitions ABB; intermixed ABC)ABB versus ABC: Stronger brain activity in the

temporal and left frontal areas, when listening toABB sequence [they prefer ABB more]There is an automatic perceptual mechanism todetect repetitions, which may help the acquisitionof the structural regularities of speech.Babbling: sounds similar across differentlanguagesIn the first 6 months, there are more vowelarticulations; occasionally there are someconsonant articulations, mostly at the back of the

mouth.At the onset of canonical babbling, consonantarticulations shift to the front. Stop consonantsdominate.At later stage (11 months and later), moreconsonants are produced stops, nasals, glides,the fricative and the glottal.Locke: 12 of the 24 consonants sounds of Englishaccounted for about 95% of the consonantsproduced.It is likely that the sound of late babbling may

serve as the building blocks for later production ofwords.The quality and complexity of canonical babblemay serve as a predictor of early languagedevelopment: frequent use of canonical syllablescorrelates with earlier onset of words, largeproductive vocabulary, and more accurate wordproduction at 24 to 36 months.Why do infants produce babbling sounds?- The motor account: Babbling is a purely non-

linguistic motor activity [excluded possibility

that external stimuli play a role] that resultsfrom the opening and closing of the mouth andjaw. [not related to language] (Babies play thisfor fun)

- The linguistic account: Babbling is alinguistic activity that reflects babies sensitivityto specific patterns at the heard of humanlanguage and their capacity to use the brainparticularly, the rhythmic patterns that bindsyllables into baby babbles, and then intowords and sentences.

Supporting Evidence for Linguistic Account:Petitto et. al.: studied the hand movements ofhearing babies born to profoundly deaf parents.[Infants would imitate / learn the sign language]

Subjects: 3 hearing babies who received nosystematic exposure to spoken language and whoinstead saw only signed language from theirprofoundly deaf parents. Another 3 hearing babieswere exposed to spoken language. [one by hand,one by mouth]The two hearing baby groups were equal in alldevelopmental respects, with the only differencebeing in the form of language input they received

(by hand or mouth).Prediction 1: Because hearing babies exposed tosign language do not use their mouth and jaw tolearn speech, the motor hypothesis predicts thattheir hand activity should be fundamentally similarto that of hearing babies acquiring spokenlanguage.[If motor hypothesis is true, two groups shouldhave similar gesture / babbling patterns]Prediction 2: If babies are born with sensitivity to

specific rhythmic patterns that are universal to alllanguages, even signed ones, then the linguistichypothesis predicts that differences in the form oflanguage input should yield differences in thehand activities of the two groups.Petitto et al.: recorded all babies hand activity inthree dimensions at age 6, 10 and 12 months.They found that hand movements made by babieswith profoundly deaf parents have a slower rhythmthan ordinary gestures (corresponds to therhythmic patterning of adult sign-syllables) and

were restricted to space in front of the body.The findings support the idea that babies aresensitive to rhythmic language patterns and thatthis sensitivity is key to launching the process oflanguage acquisition.

child language summary note

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