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

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N400-like semantic incongruity effect in
19-month-olds Processing known words in picture
contextsManuela Friedrich and Angela D.
FriedericiJ. of cognitive neuroscience, 2004,
168, 1465-1477

• Sylvia Yuan
• October 13, 2005
• Psych 593SG

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Goal

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

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N400

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

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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

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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

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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

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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 childrens cognitive
  development
• Concepts, semantic memory

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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

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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

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Procedure

• Participants were seated in front of a computer
  screen
• Session lasted 12 minutes

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Trial structure
ball (congruous) duck (incongruous)
A
Indef. article
Picture onset
Target word
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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
  childrens comprehension of the presented words
  in the experiment

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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)

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Adults ERPs
Figure 1
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Adults spatial distribution of ERPs
Figure 3
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Spatial distribution of adults difference wave
A prominent effect at central-parietal midline
sites
Figure 4
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Adults condition main effects
Table 1
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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

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Childrens ERPs
Figure 2
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Childrens spatial distribution of ERPs
Figure 3
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Spatial distribution of childrens difference wave
Negativity effect mostly in the left parietal
frontal areas
Figure 4
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Childrens condition main effects
Table 2
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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.

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Comprehension groups

• Median for comprehended words 37 (out of 44)
• Children were divided into two groups by the
  median
• High-comp. (N27) group median 42, range 38-44
• Low-comp. (N28) group median 33, range 6-37

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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

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ERPs of high low comprehenders
Figure 5
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Main condition effects
High comprehenders
Adults
Table 3
Table 1
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Spatial distribution of ERPs
More negativity in R hemisphere for
high-comprehenders
Figure 6
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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

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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

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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

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Later incongruity effect (contd)

• Negative response in children to congruous words
  as well
• stronger in low-comprehenders
• may reflect childs 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!

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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 childs general language
  abilities (e.g., Mills et al., 1993)

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Comprehension group differences (contd)

• 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

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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.
• Childrens comprehension abilities are reflected
  in strength, latency hemispheric differences of
  the incongruity effect.

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N400 in even younger children!

• 14-month-olds (N30)
• 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)
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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?