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N400-like semantic incongruity effect in 19-month-olds: Processing known words in picture contexts Manuela Friedrich and Angela D. Friederici J. of cognitive neuroscience, 2004, 16:8 , 1465-1477. Sylvia Yuan October 13, 2005 Psych 593SG. Goal.

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Sylvia yuan october 13 2005 psych 593sg

N400-like semantic incongruity effect in 19-month-olds: Processing known words in picture contextsManuela Friedrich and Angela D. FriedericiJ. of cognitive neuroscience, 2004, 16:8, 1465-1477

Sylvia Yuan

October 13, 2005

Psych 593SG


Goal Processing known words in picture contexts

  • To investigate whether adult-like mechanisms of semantic integration, as indexed by N400, are present in 19-month-olds


N400 Processing known words in picture contexts

  • An index of semantic processing in adults (e.g., Kutas & Hillyard, 1980)


N400 semantic incongruity effect
N400 semantic incongruity effect Processing known words in picture contexts

  • Semantically incongruous stimuli elicit greater N400 amplitudes than semantically congruous stimuli

  • This reflects a greater effort at semantic integration for unexpected than expected stimuli

  • Semantic priming prior to stimulus presentation can facilitate processes of semantic integration  a reduced N400


Adult like n400 in children
Adult-like N400 in children Processing known words in picture contexts

  • Picture-matching

    • 7- to 10-year-olds, greater negative component at latency 400ms to non-matching pictures in picture pairs (Friedman et al., 1992)

  • Processing visually presented words and pictures

    • 10- and 11-year-olds, antN400 to word stimuli, dual anterior negativities (N350 & N430) to picture stimuli (Coch et al., 2002)

  • Processing sentences with semantic anomalies

    • Visually stimuli: 7- to 12-year-olds (Holcomb et al., 1992)

      • N400 decreased in both amplitude and latency with age

    • Auditory stimuli: 6- to 13-year-olds (Hahne et al., 2004)

      • N400 slightly delayed for 6- to 8-year-olds


What about younger children molfese morse peters 1990
What about younger children? Processing known words in picture contexts(Molfese, Morse & Peters, 1990)

  • 14-month-olds

  • Trained on two novel words (“gibu” & “bidu”) for two objects

  • ERP responses on “mismatch” names:

    • An early negativity at 60ms

    • A positivity at 560ms

  • No N400-like incongruity effect


Why the focus on n400 in young children
Why the focus on N400 in young children? Processing known words in picture contexts

  • To learn about the neural mechanisms of early word learning

  • To evaluate the potential of using N400 to investigate other aspects of children’s cognitive development

    • Concepts, semantic memory


The present study
The present study Processing known words in picture contexts

  • Goal: to investigate whether an N400-like response can be observed in 19-month-olds to words presented in contexts

  • Task: picture-word-matching

    • Congruous condition: picture-word match

    • Incongruous condition: picture-word mismatch

  • ERP recording

  • Comparisons of spatio-temporal distributions

    • Adults vs. children (19-month-olds)

    • Among children: high vs. low comprehenders


Stimuli
Stimuli Processing known words in picture contexts

  • Pictures

    • Colored illustrations of single objects

  • 44 words

    • Basic-level words (mean item difficulty =78%)

    • Slowly spoken (mean word length: 1083 ms)

    • Each presented twice

      • Congruous context – with a matching picture

      • Incongruous context – with a non-matching picture


Procedure
Procedure Processing known words in picture contexts

  • Participants were seated in front of a computer screen

  • Session lasted 12 minutes


Trial structure

0 ms Processing known words in picture contexts

1000 ms

2000 ms

3000 ms

4000 ms

Trial structure

“ball” (congruous)

“duck” (incongruous)

“A…”

Indef.

article

Picture

onset

Target

word


Participants
Participants Processing known words in picture contexts

  • 20 adults (mean age 23.7 years)

  • 55 19-month-old German-monolingual children

    • 25 additional children were tested but excluded for crying/excessive movement (13) and too many artifacts/too much non-looking (12)

  • On average, children were looking to the monitor about 85% of the session

  • Children were split into two groups by the median comprehended words (37): low vs. high comprehenders

    • To assess whether ERP effects are related to children’s comprehension of the presented words in the experiment


Erp recording
ERP recording Processing known words in picture contexts

  • Reference electrodes: left and right mastoids

  • Trial exclusion:

    • Trials with a SD exceeding 40 μV (for adults) and 100 μV (children) in a 200ms time window were rejected

    • Mean number of trials accepted: 32 (out of 44)


Adults erps
Adults’ ERPs Processing known words in picture contexts

Figure 1


Adults spatial distribution of erps
Adults’ spatial distribution of ERPs Processing known words in picture contexts

Figure 3


Spatial distribution of adults difference wave
Spatial distribution of adults’ Processing known words in picture contextsdifference wave

A prominent effect at central-parietal midline sites

Figure 4


Adults condition main effects
Adults’ condition main effects Processing known words in picture contexts

Table 1


Summary of adult erps
Summary of adult ERPs Processing known words in picture contexts

  • An early effect of condition at temporal sites

    • 100-250ms: Congruous words more (-) than Incong. words

       Word-processing is affected by picture contexts early on

  • A broadly distributed long-lasting semantic incongruity effect

    • 300-1300ms: Incong. words more (-) than Congruous words

    • Most prominent at centro-parietal sites

    • Stronger & more extended in the right hemisphere

    • Anterior regions are also involved

       This spatial distribution matches that of the typical N400 effect in semantic priming paradigms


  • Children s erps
    Children’s ERPs Processing known words in picture contexts

    Figure 2


    Children s spatial distribution of erps
    Children’s spatial distribution of ERPs Processing known words in picture contexts

    Figure 3


    Spatial distribution of children s difference wave
    Spatial distribution of children’s difference wave Processing known words in picture contexts

    Negativity effect mostly in the left parietal & frontal areas

    Figure 4


    Children s condition main effects
    Children’s condition main effects Processing known words in picture contexts

    Table 2


    Summary of child erps
    Summary of child ERPs Processing known words in picture contexts

    • An early effect of condition at lateral front sites

      • 150 – 400ms: Congruous words more (-) than Incong. words

         Word-processing is affected by picture contexts early on

  • A broadly distributed long-lasting semantic incongruity effect

    • 700-1400ms: Incong. words more (-) than Congruous words

    • At centro-parietal & frontal sites

    • Possibly more contribution from the left hemisphere

       The spatio-temporal distribution of the semantic incongruity in 19-month-olds differs from that in adults.


  • Comprehension groups
    Comprehension groups Processing known words in picture contexts

    • Median for comprehended words: 37 (out of 44)

    • Children were divided into two groups by the median:

      • High-comp. (N=27): group median 42, range 38-44

      • Low-comp. (N=28): group median 33, range 6-37


    Results high vs low comprehenders
    Results: high- vs. low-comprehenders Processing known words in picture contexts

    • Early context effect did not change between groups

    • For the later negative incongruity effect, there were group differences:

      • High comprehenders:

        • Earlier (starting 300ms) & in right hemisphere

        • More negative to incongruous words


    Erps of high low comprehenders
    ERPs of high & low comprehenders Processing known words in picture contexts

    Figure 5


    Main condition effects
    Main condition effects Processing known words in picture contexts

    High comprehenders

    Adults

    Table 3

    Table 1


    Spatial distribution of erps
    Spatial distribution of ERPs Processing known words in picture contexts

    More negativity in R hemisphere for high-comprehenders

    Figure 6


    Summary of high vs low comp groups
    Summary of high- vs. low-comp. groups Processing known words in picture contexts

    • Low-comprehension group

      • a small semantic incongruity effect in the left hemisphere that occurs much later (from 700ms)

    • High-comprehension group:

      • Much like adults:

        • a large semantic incongruity effect starting early (300-400ms)

        • stronger effect in right hemisphere

      • Unlike adults:

        • frontal areas are more involved


    Discussion
    Discussion Processing known words in picture contexts

    Auditory-evoked response

    • Adults: N1-P2 complex (adults)

    • Children: early positive-negative waveform

      Early context effect: greater negativity for congruous words

    • Earlier for adults (100-250ms vs. 150-400ms)

    • Not about better known vs. less known words (cf. Mills et al., 1993)

    • Possibly reflects top-down priming that facilitates early phonological-lexical processing

      • Known primed vs. unknown primed words


    Later incongruity effect greater negativity for incong words
    Later incongruity effect Processing known words in picture contexts(greater negativity for incong. words)

    • First N400-like semantic incongruity effect in children under 2 years

    • Stronger involvement of frontal areas in children may reflect:

      • enhanced image-specific semantic processing, and/or

      • increased processing load


    Later incongruity effect (cont’d) Processing known words in picture contexts

    • Negative response in children to congruous words as well

      • stronger in low-comprehenders

      • may reflect child’s effort in accessing meaning of words

    • Effect stronger in high- than in low-comprehenders

       Effect reflects different semantic processing w/ cong. & incong. words, representing a child N400!


    Comprehension group differences
    Comprehension group differences Processing known words in picture contexts

    • No difference in the early context effect

      • This suggests both groups were creating appropriate lexical expectations from picture

      • Differences between groups may lie in whether phono-lexical representations of presented words primed semantic representations (to be integrated)

    • Hemispheric differences in the incongruity effect

      • These may reflect processing differences as a function of the child’s general language abilities (e.g., Mills et al., 1993)


    Comprehension group differences cont d
    Comprehension group differences (cont’d) Processing known words in picture contexts

    • High-comprehenders as fast as adults in incongruity effect

      • Possibly due to child-friendly stimuli or high-comprehenders’ knowing all (or most) word stimuli

      • Latency difference in low-comprehenders may reflect difficulties in perceptual & semantic processing


    Conclusion
    Conclusion Processing known words in picture contexts

    • 19-month-olds show a child N400 in response to hearing words that do not match pictured objects

    • The strong involvement of anterior regions in children for the incongruity effect may reflect image-specific semantic processing.

    • Adult mechanisms of semantic integration of words are present early on.

    • Children’s comprehension abilities are reflected in strength, latency & hemispheric differences of the incongruity effect.


    N400 in even younger children
    N400 in even younger children! Processing known words in picture contexts

    • 14-month-olds (N=30)

    • Picture-word matching task, with words that one-year-olds already know

      Results:

    • Early context effect

      • 200 to 400ms

      • Congruous words more negative

      • Lateral front regions

         Lexical expectations from pictures!

    • N400-like Incongruity effect

      • 400 to 1000ms, incong. words more negative

      • Mostly over central and parietal regions, some frontal

         Semantic integration & influence of priming!

    (Friedrich & Friederici, 2005)


    Questions
    Questions Processing known words in picture contexts

    • Is it really easier to go from pictures to lexical-phonological representations of words, than from representations of words to semantic representations?

    • What ERP components are observed for mismatch of grammatical gender of words to pictures?

    • If the incongruous word and its preceding article were additionally of mismatching gender (to the picture), would one expect to see stronger and/or faster N400 semantic incongruity effect?


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