modularity - nyu psychology · modularity could be true even if there was no selective language...

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MODULARITY

• What’s a module?

Fodor:

– hardwired (not assembled from more primitive processes)

– of fixed neural architecture (specified genetically)

– domain-specific (a module computes a constrained class ofspecific inputs bottom-up, focusing on entities relevant only to itsparticular processing capacities)

– fast, autonomous, mandatory (a module's processing is set inmotion whenever relevant data present themselves)

– automatic, stimulus-driven, and insensitive to centralcognitive goals.

– informationally encapsulated. In other words, other parts of themind can neither influence nor have access to the internalworkings of a module, only to its outputs.

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MODULARITY

• What would we expect of a person who’s lost their language? Orspared their language?

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MODULARITY

• Selective loss of a specific cognitive function via brain damage issupport for the modularity view.

• But the modularity thesis doesn’t necessarily predict that there shouldbe specific brain areas dedicated to specific cognitive functions. Somodularity could be true even if there was no selective languageimpairment via brain damage.

Fodor:

– of fixed neural architecture (specified genetically)

• the way brains are is determined by genes and so selective loss orsparing of language genes should lead to selective loss or sparing orlanguage.

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DEVELOPMENTAL DISORDERS WITH A GENETIC BASIS

• Specific Language Impairment (SLI):– Language problems without any obvious cause.– fifty to seventy percent of children with SLI have at least one other

family member with the disorder

• Williams Syndrome (WS):– (more or less) general cognitive retardation except in language– Results from the deletion of the long arm of chromosome 7.

If the brain is a general purpose problem solver, one’sgeneral intelligence should be predictive of abilities such aslanguage.

For people affected by WS or SLI that’s simply not true.

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Specific Language Impairment (SLI)

• Developmental language disorder in the absence of neurological,sensori-motor, non-verbal cognitive or social emotional deficits

• Affects about 7% of the population, males more often thanfemales

• A delay or deficit in the use of function morphemes. Omission offunction morphemes long after age-matched children with typicallanguage development show consistent production of theseelements.

• Diagnosis based on behavioral evaluation but is likely to have agenetic basis.

• Control group is either age-matched, IQ-matched or language-matched (usually MLU(mean length of utterance))-matched.

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SLI – language problems

"It's a flying finches, they are."

"She remembered when she hurts herself the other day."

"The neighbors phone the ambulance because the manfall off the tree."

"The boys eat four cookie."

"Carol is cry in the church.“

From: http://www.ling.udel.edu/colin/courses/ling101_f98/lecture1.html

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SLI – a grammar problem or something else?

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Gopnik: problem with functional morphology

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Gopnik: problem with functional morphology

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Rice & Wexler:SLI are stuck in the “Optional Infinitives Stage”

• Wexler (1990, 1992, 1994): In languagedevelopment, kids go through the OptionalInfinitive (OI) Stage.– lasts in normal children from birth to around 3;0.

• In the Optional Infinitive Stage:a. Root infinitives (non-finite verbs) are possible grammaticalsentences

b. These infinitives co-exist with finite forms

c. Apart from tense and agreement, the children know relevantgrammatical principles

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• A Dutch kid in the OI Stage:

(8) pappa schoenen wassen

daddy shoes wash-INF

'Daddy wash (non-finite) shoes’

(9) ik pak ‘t op

I pick it up

'I pick (fin) it up'

Infinitival in final position, as it should be.

Finite verb in second position, as it should be.


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• Development of 47 normally developing Dutch children (Wexler,Schaeffer and Bol, in press).


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• Extended Optional Infinitive Hypothesis:

Children with SLI are just like normal children exceptthat they go through the OI period for a much longertime than normal children, perhaps never reallyemerging from it.


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• Prediction for children with SLI:

Children with SLI:

a. Use OI's in languages where younger normalchildren do

b. Show the same patterns of grammatical knowledgeas normal children

• Wexler, Schaeffer and Bo:In the 6;00-8;02 year range, Dutch children with SLIstill had 15% OI's (50 of 334). The OI stage persistedmuch longer in the children with SLI.


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• Problem: SLI kids don’t just problems withtense and agreement morphology


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SLI – nonlinguistic hypotheses

• Tallal: SLI is a non-language specific deficit inthe rate of auditory processing

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Evidence for auditory processing difficulty in SLI(Tallal)

• Children with SLI have difficulty processingbrief or rapidly presented auditory stimuli.

– Normal children are able to discriminate two 75-msec tonesseparated by an interstimulus interval (ISI) as short as 8 msec,while individuals with SLI required an ISI exceeding 300 msecto perform the same discrimination at the same level ofaccuracy.

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• The degree of auditory processing deficit correlateswith the degree of language comprehension deficit.

• Early deficits in rapid auditory processing abilities bothprecede and predict subsequent language delays:

– At 6-9 months, significant differences in auditory perception betweeninfants born to families with a history of SLI and children withouthistory of SLI

– Threshold for rapid auditory processing at 7.5 months is the singlebest predictor of language outcome.

– At age 3, rapid auditory processing threshold and being male,together predict 39/41% of the variance in language outcome.

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• Rapid auditory processing difficult fordyslexics as well (recall: e.g., dyslexic rats)

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• So what would be the connection between auditoryprocessing difficulty and having trouble with functionalmorphology?

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• Leonard: it’s hard to hear little functional morphemeslike –ed or –s!

– As a consequence, there are difficulties in learningmorphological paradigms.

• Predicts crosslinguistic differences in SLI profiles.

• In languages where functional morphemes have morepercepetual salience, SLI kids should have less troublewith them.

• Leonard shows that that’s actually true in Hebrew andItalian.

– Does not follow from the Extended Optional InfinitiveHypothesis!

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SLI – genetics

• SLI seems to have a genetic component– It runs in families.

– The proportion of pairs where both twins are issignificantly higher for identical (monozygotic –single egg) than for non-identical (dizygotic –separate eggs) twins.

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KE family

• Half of the KE family are affected by SLI.

Female

Male

Shading = LanguageImpaired

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KE family – behavior

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• Not just language problems.

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KE family – brains

• Watkins et al (2002):In motor and speech-relatedbrain regions, significantlydifferent amounts grey matter inaffected family members ascompared to unaffected andcontrol groups, which did notdiffer from each other.

• Volume of caudate nucleus(part of the basal ganglia)reduced in affected members.

– Involved in regulatingvoluntary movements

– Abnormality also implicatedfor Attention DeficitHyperactivity disorder

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KE family – genes

• Vargha-Khadem et al (Science, 2001):

In the affected members of the KE family thereis a mutation in the gene FOXP2.

• A language gene?

modularity - nyu psychology · modularity could be true even if there was no selective language...

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