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Evidence for Item Based Development

E. Bates and J. C. Goodman, On the Emergence of Grammar From the Lexicon

M. Tomasello, The item-based nature of children's early syntactic development

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Evidence for Item Based Development

Introduction What is item-based development?

Studies in Lexically Based Grammar Studies in Item Based Development Conclusion

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Introduction

What is Item Based Development? Hypothesis: children’s early utterances are

organized around particular words and phrases. Speech is not abstract

So why is early speech perceived as grammatical? Children imitate and reproduce adult utterances,

appearing to posses a knowledge of grammar

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Introduction

Item based nature is most evident in the use of verbs Children tend to retain sampled sentence structure

for each particular verb, hence: A child might use “cut” in the schema Cut___

alone The same child will use in more complex

schemas for “draw” like Draw___, Draw___on____,Draw___for___

When children learn the determiners a and the, they use each with a different set of nouns, usually mutually exclusive

The cat

The house

The …

a dog

a plate

a …

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Introduction Studies in Italian regarding verb use show that:

47% of all verbs used, were used in one form only

40% were used in two or three forms The remaining 13% were highly irregular forms

(frequently used by adults), which could not be learned from generalization

Study group were 3 children, aged 18 months to 3 years

The verbs in question had 6 possible forms (first person singular, second person singular etc…)

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Introduction Transitive and Intransitive

Transitive (Subject-Verb-Object) Intransitive (Subject-Verb) Can children use verbs they’ve

heard in an intransitive context in a transitive way?

Experiment Children were introduced a novel

verb with a picture. For example “The sock is tamming” with a matching cartoon

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Introduction Later, they were encouraged, with another

cartoon, to reply to the question “What is doggie doing?”

We could expect the child to say something like “The doggie is tamming the car”

This would be creative, as the child has taken a novel verb, and taken it into a new, transitive, context

Very few children produced the transitive reply As a control for these results, other children were

exposed to the transitive form, and they had no trouble reproducing it

We’ll return to these studies later

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Introduction

Why should we care? Chomsky’s nativist approach claims

Language acquisition takes place quickly and effortlessly because children have full linguistic competence at birth

Language acquisition relies only indirectly on the language they are exposed to

Children are creative in early stages, because of innate grammar proficiency

Item based development disagrees with this, and questions the presence of adult grammar in children’s language

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Definitions Grammar

Grammar is the discovery, enunciation, and study of rules governing the use of language. The set of rules governing a particular language is also called the grammar of the language.Or as previously described: A set of sentences with a finite structural description.

Lexicon What words are, how the vocabulary in a language is

structured, how people use and store words, how they learn words, the history and evolution of words, types of relationships between words as well as how words are created.

Lexicon is a word of Greek origin (λεξικόν) meaning vocabulary

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First Debate

Grammar from the Lexicon What does this mean? Grammar has vocabulary qualities Grammar and vocabulary are learned the same Same mental mechanisms used for both

Chomsky Grammar cannot be learned! (in finite time) It is different from vocabulary

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Nature of Debate

Epistemology Empiricism Vs. Nativism

Plato Vs. Aristotle

Do we have a special grammar organ, or are we just really smart? Really smart = innate abilities not specific to

language Soft empiricist claim

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Emergentism

Emergentism Solutions to a problem are unpredictable

We will explore the Emergentist approach Emphasizing the union between grammar and

lexicon

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The Giraffe

Is the giraffe’s neck a “leaf eating organ”?

Is the giraffe itself a leaf eating organ?

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Humans and Giraffes

Hypotheses: Human grammar has evolved like the giraffe’s neck Human beings have walked into a problem space

that other animals cannot perceive Appearance of language applied pressure on

neural mechanisms in the brain

So… Human beings have symbols for everything When these symbols appeared together, grammar

emerged

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Evidence

Two types of evidence grammar and the lexicon same mental systems

(neural mechanism) Strong relation between grammar/lexical

development Overlap in symptoms of brain damage

The same mental systems for grammar and the lexicon have other roles Same mental systems do other things

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Evidence for Item Based Development

Introduction Studies in Lexically Based

Grammar Normal Children Atypical Populations Lexicon and Grammar in the Adult Brain

Studies in Item Based Development Conclusion

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Studies

Research in normal children Relation between lexical development and

grammar complexity Target group: normal children, 8 to 30 months of

age

Early language development in atypical populations Comparison with normal children Early/late talkers, focal brain injury, Williams and

Down Syndrome, SLI

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Studies

Grammar and lexicon in the adult brain Does modularization occur in a later stage? We will examine neurological patients

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Development in Normal Children General Maturation of speech development

(English) Phonology (reduplicative babbling) - 6 to 8 months Meaningful speech – 10 to 12 months Additional 4 to 8 months in one word stage Burst in vocabulary growth (combinations) - 16 to 20 months Second burst, morphological – 24 to 30 months Mastering of morphological and syntactic structures – 3 to

3.5 years

Appears like maturation of three mental modules Phonological Lexical Grammatical

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Grammar, Comprehension Production

Zones of acceleration for each domain are separated by many weeks

Lets try and find a connection

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Vocabulary and MLU

Correlation between vocabulary and MLU Best indication for 28 month MLU is 20 month

vocabulary Correlation is not cause

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Cross Sectional Grammar Complexity

Individual differences around the grammar on vocabulary function are rather small (small s.d.)

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Grammar and Expressive Vocabulary

Tight correlation between grammar and vocabulary

Clear dissociation between words comprehended and words produced

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Grammar and Expressive Vocabulary

Fan shaped pattern Implies that word comprehension is a prerequisite

for expressive grammar not sufficient Comprehension and production can dissociate

Grammar We expect vocabulary to put a ceiling on grammar

complexity, until a threshold is reached grammar will then decouple with vocabulary Instead, grammar and vocabulary remain tightly

coupled

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Important Points

Study follows children through critical stage in development

Is the correlation we found a correlation of grammar with itself? Vocabulary includes many prepositions, articles

and other grammatical words Removal of such words yields close results

Similar study conducted in Italian Similar results

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Longitudinal Study We can see that the link between grammar and

lexical development extends to longitudinal studies as well

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Explaining the Link

Perceptual bootstrapping Grammatical function words are short, low in

stress and difficult to perceive

Logical bootstrapping Children cannot understand relational terms, until

they understand what they relate to. So, grammar depends on the lexicon

Syntactic bootstrapping Children exploit sentential information to extract

the meaning of a novel word. Grammar words are thus obtained

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Explaining the Link

Nonlinear dynamics of learning in a neural network Experiments in neural network learning (even past

tense learning) has resulted in non-linear curves

Lexically based grammar The relation observed would be exactly what we

would expect, if grammar is part of the lexicon

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Development in Atypical Populations

We would like to find a pediatric population which displays a dissociation between grammar and the lexicon

We shall examine Late and early talkers Early focal lesions Williams Syndrome and Down Syndrome Specific Language Impairment (SLI)

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Late and Early Talkers

Late talkers Children of age 18 to 24 months who are in the

bottom 10th percentile for expressive vocabulary

Early talkers Children of age 12 to 24 months who are in the top

10th percentile for expressive vocabulary

Do grammar and vocabulary dissociate in these two groups?

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Late and Early Talkers Grammar-on-vocabulary function for two children Age 16 to 30 months Age is a poor predictor of vocabulary and grammar

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Two Case Studies

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Two Case Studies MW

17 months old, expressive vocabulary 596 words, MLU 2.13

SW 21 months old, expressive vocabulary 627 words, MLU 1.12

Deductions It appears that SW is lagging in grammatical development

(just begun combining words). Possible dissociation Despite huge vocabulary, her grammatical level is average

for her age However, SW displays advanced morphology (knows falling

and fell) Dissociation could be explained by short auditory memory

We will use this argument again

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Early Focal Lesions

Assuming different neural mechanisms for grammar and vocabulary We expect to find dissociation between grammar

and lexicon, in relation to congenital(Present at birth) brain injuries

We also expect conformity with classic adult aphasia studies (discussed later) Delay in grammar development for left frontal

damage (Broca’s area) Delay in lexical development for posterior left

damage (Wernicke’s area)

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Early Focal Lesions

No evidence in favor of predictions With older children

Plastic reorganization of brain for early focal lesions

Studies conducted during first stages of language acquisition might prove insightful Lesion site has impact on lingual development Target group: 10 months to 12 years

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Classic Language Areas Adults suffering damage to Broca’s area usually

display inability to produce or comprehend grammatically complex sentences

Damage to Wernicke’s area usually manifests in impairment of comprehension, and natural sounding speech without meaning

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Early Focal Lesions Absence of left right differences

Absence of global differences Small but reliable disadvantage in word comprehension

for right focal damage Wernicke’s area

Left temporal cortex Delayed in expressive language (10 to 60 months) Reliable disadvantage

Broca’s area No effects recorded for Broca’s Area Front damage is symmetric for right and left (during 19

to 31 months period) Conclusion: temporal lobe of left hemisphere is critical,

but the frontal lobes become involved in later stages

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Early Focal Lesions

Disappearance of left temporal effect Children with (any) early focal lesion rank below

average at the age of 5 to 7 years Left lesion disadvantage disappears at this age,

indicating that some plastic reorganization has taken place (the discussed Wernicke’s area)

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Conclusions For Early Focal Lesions Study group ranks well within 10th to 90th

percentile of normal population in grammar-on-vocabulary function

In a normal group of 19 children, we would also expect 1-4 children in the outskirts

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Williams Vs. Down Williams (WMS) and Down (DNS)

syndromes Both constitute a form of genetically based mental

retardation Mean IQ’s between 40 and 60 Contrast in grammar development

Down Language abilities below mental age Severe function word omissions and structural

simplifications

Williams Below mental age Language abilities surprisingly good compared with

other mental abilities

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Williams Vs. Down When do groups separate?

Both groups are late talkers, seriously delayed in word comprehension and production during the infant scale (8 to 16 months in normal children)

Though still 2 years delayed in vocabulary, during toddler scale (16 to 30 months in normal children), WMS children display good grammar capabilities (Within 10th to 90th percentiles)

DNS children remain at a disadvantage

First evidence of dissociation WMS usually score low on visual short term

memory DNS usually score low on auditory short term

memory A result of perceptual impairment?

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Williams Vs. Down

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Specific Language Impairment Definition: A delay in expressive language abilities

that is 1 standard deviation below average The term specific may be misleading

Low attention span also diagnosed Studies show that grammatical morphology is

highly effected This dissociation can also be explained by a

difficulty of processing rapid auditory data

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Grammar and Lexicon in the Adult Brain

Conclusions at this point We’ve seen an interdependence between

grammar and lexicon compatible with unified grammar/lexical approach

Adult neural mechanisms Does modularization occur in later stages This is not incompatible with findings so far

We will present two kinds of evidence Neural imaging of lexical and grammatical

processing Dissociation between lexicon and grammar in

patients with focal brain injury (or lack of)

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Grammar and Lexicon in the Adult Brain Some points to keep in mind

All knowledge is in the brain Short of finding neural activity at birth, can’t know

source of knowledge (innate/acquired) Differences in experience must be accompanied in

differences in neural activity Different responses to two classes of stimuli would

require these classes be associated with different patterns in the brain

Different brain activity accounted for Nouns vs. Verbs Animal words Vs. Tool Words High/low frequency words

Classifying by brain activity would result in two many “systems”

Difficulty in classifying by neural activity

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Grammar and Lexicon in the Adult Brain

Localization and domain specificity are not the same If an area is used for language processing, it

does not imply dedication Difficult to prove negative things (like

dedication) Broca’s area known to mediate some motor

tasks as well as language

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Definitions

Aphasia Aphasia is a loss or impairment of the ability to

produce or comprehend language, due to brain damage. It is usually a result of damage to the language centres of the brain (like Broca’s area).

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Different Arguments

Neural Imaging So far no convincing study conducted Evidence of dissociation between grammar and

lexicon exist, but vary from study to study

Adult aphasia presents a more interesting challenge Damage to Broca’s area known to create

grammatical difficulties Is Broca’s area central for grammar processing? Damage to Broca’s area results in processing

impairments that transcend language

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All Aphasic Patients have Lexical Difficulties

Anomia Deficit in word retrieval

All Aphasic patients have some sort of Anomia Hence, a grammar deficit is always accompanied

by a lexical deficit

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Expressive Agrammatism Studies in English show that patients of Broca’s

aphasia suffer from agrammatism, while Wernicke’s aphasia patients do not Agrammatism for Wernicke’s aphasia only

detected in highly inflected languages (like German and Czech)

English is poor in inflections So, the above hypotheses is a result of studies

conducted in English! The following table summarizes agrammatism in

different populations

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Expressive Agrammatism

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Similar Symptoms

Review of the table reveals that Patients with agrammatical symptoms, have

similar symptoms relating to the lexicon Patients with omission pattern in grammar,

have word retrieval failures (common in Broca’s aphasia)

Patients who display word substitution in grammar (in instead of at) also display substitution in vocabulary (paraphasia). Common to Wernicke’s and WMS

Etc Results suggest that grammatical and lexical

deficits have common cause

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Receptive Agrammatism Receptive agrammatism

Is characterized by a difficulty of processing inflections and closed-class words. More difficulties with non-canonical word order types For example The rabbit is being thrown by the bear

is more difficult than the bear is throwing the rabbit present in normals as well, under the influence of

noise, or other interference

Closed-class words – part of the vocabulary of a language that isn’t likely to change (such as pronouns)

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Receptive Agrammatism Not unique to aphasia populations, present in

normals under adverse conditions

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Evidence for Item Based Development

Introduction Studies in Lexically Based Grammar Studies in Item Based

Development Investigating children’s verb usage Building a Usage Based Model

Conclusion

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Recalling Previous Experiment Transitive and Intransitive

Transitive (Subject-Verb-Object) Intransitive (Subject-Verb) Can children use verbs they’ve

heard in an intransitive context in a transitive way?

Experiment Children were introduced a

novel verb with a picture. For example “The sock is tamming” with a matching cartoon

Later, they were encouraged, with another cartoon, to reply to the question “What is doggie doing?”

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Recalling Previous Experiment

The above experiment was conducted with children aged 2-3 years old

Other studies have shown that children of age 3-4, have no difficulty assimilating a novel verb and using it creatively

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Similar Experiments in English

Novel verbs were presented in different sentence frames Presentational construction (This is called groping) Imperative construction (Tam, Anna!) Passive construction (Ernie is getting meeked by

the dog)

The children were encouraged to produce transitive sentences Children under the age of 3 were very poor in

creative constructions

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Inducing non-Grammatical English Presenting 3 novel verbs

Age groups: 2;8, 3;6, 4;4 Verbs introduced

One in normal SVO (transitive) form Ernie meeking the car

One in SOV form Ernie the car tamming One in VSO form Gropping Ernie the car

Almost everyone produced SVO forms with the verb they heard in that form

When encouraged to use the incorrect forms The older children corrected the verb to normal

transitive form The younger children generally produced the illegal

forms in which the verb was introduced These results are inconsistent with an innate proficiency

in grammar

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Additional Attempts

Key to Graph

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Additional Attempts

As we can see, creativity improves with age

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Two Supporting Facts

Perhaps young children are reluctant to use novel words in novel ways? Studies show that children freely use novel nouns

in novel sentence frames

Perhaps children have production difficulties? Children participating in the studies proved no

better in comprehension, than they did in production

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Introduction

As we’ve seen, the above results contradict Chomsky’s nativist approach Chomsky’s nativist approach claims that

Language acquisition takes place quickly and effortlessly because children have full linguistic competence at birth

Language acquisition relies only indirectly on the language they are exposed to.

Children are creative in early stages, because of innate grammar proficiency

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Possible Nativist Retorts

Performance Limitations Children have performance limitations that inhibit

the expression of innate knowledge However: children display no limitations when

learning new nouns, or reproducing familiar sentence frames with novel verbs

Genes for adult like grammar turn on later Perhaps early speech is item-based, but

appropriate “brain circuits” turn on at later stages Problem: All the above experiments were

conducted on the English transitive form, which children could produce with other verbs

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Usage Based Model Nativist model is lacking

At odds with empirical data A new model is needed

Usage Based Model This approach tends to characterize a child’s language in

terms of cognitive and communicative processes involved Children begin categorizing concrete nouns quite early Only later do children analyze the syntactic structure of

their item-based constructions

Adult end point Instead of abstract grammar, we have an inventory of

symbolic resources This resembles the lexically based grammar we spoke of

earlier

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Usage Based Model Processes involved

Imitative learning Children reproduce adult utterances, but not

only reproduce, but for the same communicative purpose (they recognize it has meaning)

Imitative learning for all constructions Children find abstract categories and schemas

Children find patterns Done in concrete nouns quite early (Daddy’s car

into Daddy’s_____) Children see both structural and functional

similarities in sentences like dad kisses mommy, I hit Jeffery

Hypothesis: a critical mass of verbs is necessary

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Usage Based Model

Processes (continued…) Children combine structures and schemas

For example, the child combines See___(Mommy/Ball) with Daddy’s___(Car) into See daddy’s car

Child must realize, that Daddy’s car is somehow equivalent to Mommy or Ball

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Evidence for Item Based Development

Introduction Studies in Lexically Based Grammar Studies in Item Based Development Conclusion

Grammaticalization Lexically based grammar

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Conclusion

So we reject the Nativist Account Where does language come from? Hypothesis

Grammatical structures do not come from the human genome

Children do not invent grammar A reasonable theory would be that once the homo

sapiens learned symbolic communication, a string of successive symbols began to take form. This is called Grammaticalization

Grammaticalization processes are well attested to in literature of the recent past

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Grammaticalization

What is it The inventory of symbolic conventions is universal

(the existence of a past, all humans have hands etc.)

Peculiarities of each language are governed by what that community thinks it’s important to talk about

The structures and conventions of a language evolve, adapt and change. This is called Grammaticalization

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Examples

From English The future tense with the word will (used for

volition). “I will it to happen” turns to “It will happen”

Go was used to indicate movement, so “I am going to the store” turned into “I am going to sleep”

The past perfect tense, with have, is most likely to have derived from sentences like “I have a broken finger”, turning into “I have broken a finger”

Phrases like “On the top of” or “In the side of” turn into “On top of” or “Inside of”, eventually reducing to “atop” or “inside”

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Conclusion

So how do we account for abstraction? Chomsky noted that abstraction must be

contributed from the individual child’s mind (The sentences themselves are not abstract)

It is difficult to imagine children applying abstract properties to the language through some innate capability

In accord with recent data, it is possible to imagine children using their cognitive and vocal auditory processing skills on the historical product of Grammaticalization

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The Origin of Language

And so we can hypothesize Human language originated from our adaptation to

symbolic communication The grammatical structures of modern languages

are due to the process of historic Grammaticalization and the analysis of that product using Imitation Schema formation Structural combiningDone by separate individuals