Sylvia yuan october 13 2005 psych 593sg
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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

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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


Sylvia yuan october 13 2005 psych 593sg

Goal

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


Sylvia yuan october 13 2005 psych 593sg

N400

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


N400 semantic incongruity effect

N400 semantic incongruity effect

  • 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

  • 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?(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?

  • 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

  • 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

  • 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

  • Participants were seated in front of a computer screen

  • Session lasted 12 minutes


Trial structure

0 ms

1000 ms

2000 ms

3000 ms

4000 ms

Trial structure

“ball” (congruous)

“duck” (incongruous)

“A…”

Indef.

article

Picture

onset

Target

word


Participants

Participants

  • 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

  • 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

Figure 1


Adults spatial distribution of erps

Adults’ spatial distribution of ERPs

Figure 3


Spatial distribution of adults difference wave

Spatial distribution of adults’ difference wave

A prominent effect at central-parietal midline sites

Figure 4


Adults condition main effects

Adults’ condition main effects

Table 1


Summary of adult erps

Summary of adult ERPs

  • 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

    Figure 2


    Children s spatial distribution of erps

    Children’s spatial distribution of ERPs

    Figure 3


    Spatial distribution of children s difference wave

    Spatial distribution of children’s difference wave

    Negativity effect mostly in the left parietal & frontal areas

    Figure 4


    Children s condition main effects

    Children’s condition main effects

    Table 2


    Summary of child erps

    Summary of child ERPs

    • 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

    • 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

    • 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

    Figure 5


    Main condition effects

    Main condition effects

    High comprehenders

    Adults

    Table 3

    Table 1


    Spatial distribution of erps

    Spatial distribution of ERPs

    More negativity in R hemisphere for high-comprehenders

    Figure 6


    Summary of high vs low comp groups

    Summary of high- vs. low-comp. groups

    • 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

    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(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


    Sylvia yuan october 13 2005 psych 593sg

    Later incongruity effect (cont’d)

    • 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

    • 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)

    • 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

    • 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!

    • 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

    • 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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