First steps in Language Acquisition: Evidence from ERPs

Max Planck Institute for Human Cognitive and Brain SciencesTrieste, 07.05.2006

First steps in Language First steps in Language

Acquisition: Evidence from Acquisition: Evidence from

ERPsERPs

Angela D. Friederici

Max Planck Institute for Human Cognitive and Brain SciencesLeipzig, Germany


• High temporal resolution as it measures the brain‘s activity millisecond by millisecond.

• No behavioral reaction necessary.

Method of Event Related Potential (ERP)


ERP method

AUDITORY EVENT-RELATED POTENTIAL-6 µV

+6 µV

Time (ms)STIMULUSONSET

one secS S S S

ONGOING EEG

ELAN

P200

N400

P600

AUDITORYSTIMULUS

(S)

Amplifier

Signalaverager

200 400 600 800 1000

ERP method


Infants' first Steps into Language are Based on Prosodic Information

The identification of syntactic phrase boundaries is eased by prosodic information as each intonational phrase boundary is a syntactic phrase boundary.

The identification of word boundaries (word onset and offset) is eased by information about word stress. In a language like English or German, in which the stress of two syllable words lies predominantly on the first syllable, stress information can certainly help to identify word onsets.


Syllable Length and Word Stress Discrimination

• Word stress in German is predominantly (› 90% of two syllable words) on the first syllable.

• Word stress is indicated by a number of acoustic parameters with syllable duration (length) being the most prominent one.

• In order to investigate the infants' ability to discriminate words stressed on the first syllable versus words stressed on the second syllable we decided to initially investigate the infants' ability to discriminate between a long and a short syllable. We did so by using the MMN paradigm.


Mismatch Negativity (MMN)

... is a pre-attentive response.

... is elicited by any discriminablechange in repetitive auditory stimulation (oddball design):

... is the result of deviance detection.

sta devstasta sta sta


Experiment 1Discrimination of Syllables of Different Duration

/ba:/ 341 ms

/ba/ 202 ms

Standard 5/6

Deviant 1/6

2. Block ba ba ba ba baa ba ba ba baa ba ba ...

1. Block baa baa baa baa ba baa baa baa ba ...


Adults: Difference wave between Deviant-Standard

The Mismatch Negativity MMN

Source: Friedrich, Weber & Friederici, Psychophysiology, 2004


ERP and difference waves (Deviant-Standard)of 2-month-old infants


Source: Friederici, Friedrich & Weber, NeuroReport, 2002


Difference waves for long syllable in 2-month- old infants and adults


Source: Friederici et al., NeuroReport, 2002; Friederici et al., 2004


Summary Experiment 1

• Infants by the age of 2 months are able to discriminate long syllables from short syllables.

• Infants more easily discriminate a long syllable in a stream of short syllables than vice versa.

• Infants show a positivity as MMN response.


One of the hypotheses we persued was the notion that a major underlying cause of Specific Language Impairment (SLI) is a deficiency in processing prosodic information.

If so, infants with risk for SLI may be deficient already in discriminating long from short syllables at the age of 2 months.

Hypothesis for SLI


Experiment 1b

Source: Friedrich, Weber & Friederici, Psychophysiology, 2004

Difference waves for 2-month-olds with and without risk for SLI


Summary Experiment 1b

Infants with risk for SLI differ from those with no risk already at the age of 2 months in their perceptual ERP parameters for duration discrimination.


Experiment 2Discrimination of Different Stress Patterns

/ba:ba/ 750 ms

/baba:/ 750 ms

Standard 5/6

Deviant 1/6

1. Block baaba baaba baaba babaa baaba baaba

2. Block babaa babaa babaa babaa baaba babaa


Difference waves 4- and 5-month-old infants

Experiment 2Discrimination of Different Stress Patterns

Source: Weber, Hahne, Friedrich & Friederici, Cognitive Brain Research, 2004

MMN



• Infants by the age of 5 months are able to discriminate word stress of two syllable words.

• Discrimination is evident as indicated by MMN for the trochaic pattern (stress on first syllable) which is the predominant pattern in German.


Difference waves 5-month-old infants

Experiment 2bDiscrimination of Different Stress Patterns


MMN


Summary Experiment 2b

Infants with risk for SLI demonstrate a reduced discrimination ability for the language-specific trochaic pattern at the age of 5 months.


Stress Pattern DiscriminationNovel Analysis: 5-month-olds


At-risk group classification based on word production at

2 years.

MMN


Processing Intonational Phrase Boundaries

As each intonational phrase boundary is a syntactic phrase boundary, the identification of an intonational phrase boundary provides an easy entrance into the syntax of a given language.

How can we investigate this identification process using ERPs?


Prosodically correct conditions

(A) correct: Late Closure[IP1 Peter verspricht Anna zu ARBEITEN ] # [IP2 und ...

('Peter promises Anna to work and ...

(B) correct: Early Closure[IP1 Peter verspricht ] # [IP2 ANNA zu entlasten ] [IP3 und ...

('Peter promises to support Anna and ...

Experiment 3

Source: Steinhauer, Alter & Friederici, Nature Neuroscience, 1999


Source: Steinhauer, Alter & Friederici, Nature Neuroscience, 1999

Effect of Intonational Phrase BoundarySpoken sentences: Adults


Spoken Sentences: 8-month-old Infants

Source: Pannekamp, Weber & Friederici, NeuroReport, in press



Infants by the age of 8 months show a brain response to intonational phrase boundary similar to that of adults.

adults 8-month-old infants


2 8

MMN

5

Development of Prosodic Perception

basic mechanisms underlying the identification of word

boundaries

discrimination of

syllable duration

CPS

basic mechanisms underlying the identification of

intonational (syntactic) boundaries

sensitivity to intonational phrase

boundary

discrimination word stress pattern

Months of ageBirth

ERP-

correlates

Source: Friederici, Trends in Cognitive Sciences, 2005


To understand mechanisms of early word learning, it is important to know whether the infant’s brain acts in an adult-like manner when processing meaningful words in meaningful contexts.

The N400, a negative component in the ERP of adults, reflects neural mechanisms of semantic integration into context.

Processing Lexical-Semantic Information


In the present study, we investigated whether the neural mechanisms observed for adults are already working during early language acquisition when infants know only a few words.

Experiment 4: Lexical-Semantic Processing


Using a picture-word design we recorded the ERP response of 12-, 14- and 19-month-old infants on slowly spoken basic level words. While infants were looking at sequentially presented pictures they were acoustically presented with words that were either congruous or incongruous to the picture contents.



congruous

incongruous

Lexical-Semantic Processing Paradigm

“Ball” (ball)

“Ente” (duck)

“Lampe” (lamp)

“Schaf” (sheep) time

incongruous

congruous


Adapted from Friederici,Trends in Cognitive Sciences, 2005

Adults


Source: Friedrich & Friederici, Journal of Cognitive Neuroscience, 2004

ERP of 19-month-old infants


N400



Source: Friedrich & Friederici, Psychophysiology, 2005

ERP of 19-month-old infants: normals and at riskrisk (low scores on word & sentence production)

Normals At risk



19-month-olds Adults



14-month-olds 19-month-olds Adults



12-month-olds 14-month-olds 19-month-olds Adults


400 – 700 ms 400 – 700 ms 400 – 700 ms

12-month-olds 14-month-olds 19-month-olds


ERP of 12-month-old infants



early neg.

early neg.



• In our study, developmental changes in the early time range reflect increased familiarity with the presented words. The early negativity for congruous words in 12-month-old infants is interpreted as facilitation of phonological processing by lexical priming.

• The later centro-parietal negativity for incongruous words in 14- and 19-month-old infants is regarded as infant N400.

Early starting ERP differences in the infants’ temporal brain region have previously been linked to processing differences between known and unknown words (Mills et al., 1993).

Lexical-Semantic Processing


Conclusion Experiment 4

The occurrence of a phonological-lexical priming effect in both age groups implies that not only 14-, but also 12-month-old infants already create lexical expectations from picture contents. This result suggests the existence of some lexical-semantic knowledge even in 12-month-old infants. Infants at that age, however, do not display a N400 semantic incongruity effect that is present in 14-month-old infants. From that we conclude that N400 maturates during the first half of the second year of life.


months of age

2

CPSMMN

Birth 4 6 8

Identification of word boundaries

Identification of

intonational boundaries

Discrimination

of phonemes

Discrimination

word stresspattern

Sensitivity tointonational

phrase boundary

Adapted from Friederici, Trends in Cognitive Sciences, 2005

ERP

correlates

Developmental stages

Months of age

53 7

Development of Auditory Language PerceptionBasic stages and ERP correlates

12

Lexical processing

Lexical semantics

Lexical form

N400

14


months of age

2

CPSMMN

Birth 4 6 8

Identification of word boundaries

Identification of

intonational boundaries

Discrimination

of phonemes

Discrimination

word stresspattern

Sensitivity tointonational

phrase boundary

Adapted from Friederici, Trends in Cognitive Sciences, 2005

ERP

correlates

Developmental stages

Months of age

53 7

Development of Auditory Language PerceptionBasic stages and ERP correlates

12

Lexical processing

Lexical semantics

Lexical form

N400

14

Sentence processing

Selectionalrestrictionof verbs

Localphrase

structurebuilding

ELAN-P600

19 32


Manuela Friedrich

Anja Hahne

Birgit Herold

Claudia Männel

Regine Oberecker

Ann Pannekamp

Christiane Weber

MAXPLANCK

INSTITUTE

FOR

LEIPZIG

HUMANCOGNITIVE AND BRAIN SCIENCES


Experiment 5: Semantic Processes in Sentences

The next question is:

Do infants at that age also process semantic relations in sentential context?

Experiment 5 examines this question.


Semantic Violation

incorrect:

"Das Lineal wurde gefüttert"

"The ruler was fed"

correct:

"Das Baby wurde gefüttert"

"The baby was fed"

correctincorrect

CZ

N400Cz-5

5

µV

0 0.5 1 sec

semantic violation

Source: Hahne & Friederici, Cognitive Brain Research, 2002


Stimulus Material

correct Die Katze trinkt die

Milch. The cat drinks the milk.

semantically incorrect Die Katze trinkt den

Ball. The cat drinks the ball.

Source: Friedrich & Friederici, NeuroReport, 2005



N400

Experiment 5: ERP of 24-month-olds


Experiment 5: ERP of 19-month-olds


N400

2607 Berlin IACL 2005



The data show that children at the age of 19 months can process semantic relations between words in a sentence quite similar to adults.

The N400 effect, however, is longer lasting than in adults. As the N400 is taken to reflect integration difficulties, these data suggest that integration processes take longer in young children compared to adults.


In adult syntactic processing ERP studies, the ELAN has been interpreted to reflect highly automatic phrase structure building processes, whereas the P600 is taken to reflect processes of syntactic integration (e.g. Hahne & Friederici, 1999).

If so, the P600 should be present earlier than the ELAN which was shown in 6- to 13-year-old children for syntactic violations in passive sentences (Hahne, Eckstein & Friederici, 2003).

Processing Syntactic Information


incorrect:

"Die Bluse wurde am gebügelt."

"The blouse was on ironed."

correct:

"Das Hemd wurde gebügelt."

"The shirt was ironed."

correctincorrect

F7

Source: Hahne & Friederici, Cognitive Brain Research, 2002

-5

5

µV

0 0.5 1 sec

F7ELAN

-5

5

µV

0 0.5 1 sec

Pz

P600PZ

Syntactic Violation


Experiment 6 investigates at what age we can detect syntax-related ERP components. In this experiment syntactic violations were realized in simple active sentences.

Experiment 6: Syntactic Processing


Stimulus Material

correct Der Löwe brüllt.The lion roars.

syntactically incorrect Der Löwe im brüllt.The lion in the roars.

correct filler item Der Löwe im Zoo brüllt.The lion in the zoo roars.

Source: Oberecker, Friedrich & Friederici, Journal of Cognitive Neuroscience, 2005


ELAN

P600

Experiment 6: Syntax adults




ELAN

P600

Experiment 6: Syntax 32-month-old children


Source: Oberecker & Friederici, submitted

P600

Experiment 6: Syntax 24-month-old children


P600

ELAN

P600

ELAN

P600

24-month-old children

32-month-old children

Adults

-10 µV

0.8 1.6

s

10

-10 µV

0.8 1.6

s

10

-5 µV

0.8 1.6

s

5

correctincorrect

correctincorrect

correctincorrect



The data presented show for the first time that the infant‘s brain is sensitive to phrase structure violations in auditorily presented sentences already at the age of 2.5 years. Their ERP pattern reflects initial processes of structure building (ELAN) as well as late processes of syntactic integration difficulty (P600).


Experiment 7: Syntax 32-month-olds at risk

Source: Oberecker & Friederici, in preparation


P600

ELAN

P600

No risk24-month-olds

No risk32-month-olds

-10 µV

0.8 1.6

s

10

-10 µV

0.8 1.6

s

10

-15 µV

0.8 1.6

s

15

correctincorrect

correctincorrect

correctincorrect

Risk32-month-olds



Children with risk for SLI do not demonstrate an ELAN-P600 pattern at the age of 32 months.

This suggests that children classified at risk for SLI are delayed in their syntactic processing abilities, not only with respect to initial on-line syntactic structure building, but also with respect to late processes of syntactic integration.


Processing Phonotactically legal and illegal Pseudowords

Source: Friedrich & Friederici, Psychophysiology, 2005

ERP of 19-month-old infants: normals and at risk (low scores on word & sentence production)

Normals At risk

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First steps in Language Acquisition: Evidence from ERPs