Timing in mind and brain: lexical access

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Timing in mind and brain lexical access

• Liina Pylkkänen
• Linnaea Stockall
• Karen Froud

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Goals

• Isolate neural activity associated with
  linguistic processing by using linguistic theory
  and psycholinguistic models/results as guiding
  hypotheses about the neurobiology of language.
• Use neural activity associated with linguistic
  processing to address questions about linguistic
  processing and structure that are not easy to
  investigate behaviorally.

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Lexical access

• Manipulate the computational demands of lexical
  processing in such a way that response times
  (RTs) are affected in tasks that are believed to
  reflect the speed of lexical access.
• Identify a neural predictor of behavioral lexical
  effects.
• If such neural activity is associated with
  automatic lexical processing, rather than the
  experimental task, it should also be possible to
  manipulate RT without affecting the activity in
  question.
• Use neural activity associated with lexical
  processing to address questions about lexical
  processing and structure that are not easy to
  investigate behaviorally.

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Magnetoencephalography (MEG)
EEG
http//www.ctf.com/Pages/page33.html
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Magnetoencephalography (MEG)
EEG
MEG
http//www.ctf.com/Pages/page33.html
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Magnetoencephalography (MEG)
Distribution of magnetic field at 93 ms (auditory
M100)
Averaged epoch of activity in all sensors
overlapping on each other.
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Magnetoencephalography (MEG)
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Lexical access

• Manipulate the computational demands of lexical
  processing in such a way that response times
  (RTs) are affected in tasks that are believed to
  reflect the speed of lexical access.
• Identify a neural predictor of behavioral lexical
  effects.
• If such neural activity is associated with
  automatic lexical processing, rather than the
  experimental task, it should be possible to
  manipulate the activity independently of RT.
• Use neural activity associated with lexical
  processing to address questions about lexical
  processing and structure that are not easy to
  investigate behaviorally.

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Frequency (Embick et al. 2001) - high frequency
? faster response due to higher resting level
Repetition (Pylkkänen et al. 2001) - repeated
stimulus ? faster response due to priming
Open-class words from 6 frequency bins
nonwords.
4 stimulus categories repeated word DOG
DOG nonrepeated word DOG WIND repeated
nonword GULK GULK nonrepeated nonword DOG
GULK
(Embick, Hackl, Shaeffer, Kelepir, Marantz,
Cognitive Brain Research, 2001)
(Pylkkänen, Stringfellow, Flagg, Marantz,
Biomag2000 Proceedings, 2000)
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M170 M250 M350
CAT
0 200 300 400 Time msec
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M350 the 1st MEG component sensitive to lexical
factors
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CAT
0 200 300 400 Time msec
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Lexical access

• Manipulate the computational demands of lexical
  processing in such a way that response times
  (RTs) are affected in tasks that are believed to
  reflect the speed of lexical access.
• Identify a neural predictor of behavioral lexical
  effects.
• If such neural activity is associated with
  automatic lexical processing, rather than the
  experimental task, it should also be possible to
  manipulate RT without affecting the activity in
  question.
• Use neural activity associated with lexical
  processing to address questions about lexical
  processing and structure that are not easy to
  investigate behaviorally.

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Phonotactic probability/density early
facilitation

• Same/different task (low-level)
• RTs to nonwords with a high phonotactic
  probability are speeded up.

RT
Sublexical frequency effect
RT
(Vitevich and Luce 1998, 1999)
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Phonotactic probability/density later inhibition

• Lexical decision (high-level)
• RTs to nonwords with a high phonotactic
  probability are slowed down.

Competition effect
RT
High probability
MIDE
RT
YUSH
Low probability
(Vitevich and Luce 1998, 1999)
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Phonotactic probability/density early
facilitation -- later inhibition

• Would the M350s of high probability/density
  stimuli show facilitation or inhibition?

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Materials (visual)

• Four categories of 70 stimuli

• Lexical decision.

(Pylkkänen, Stringfellow, Marantz, Brain and
Language, 2002)
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Effect of probability/density (single subject)
RT 640.36
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Effect of probability/density (single subject)
RT 640.36
RT 620.03
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Effect of probability/density (n10)
(Pylkkänen, Stringfellow, Marantz, Brain and
Language, 2002)
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M350 (i) 1st component sensitive to
lexical factors (such as lexical frequency)
(ii) not affected by competition
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Earlier effect of probability/density on M250
amplitude (n10)

(Pylkkänen, Stringfellow, Marantz, Brain and
Language, 2002)
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Linnaea
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Lexical access

• Manipulate the computational demands of lexical
  processing in such a way that response times
  (RTs) are affected in tasks that are believed to
  reflect the speed of lexical access.
• Identify a neural predictor of behavioral lexical
  effects.
• If such neural activity is associated with
  automatic lexical processing, rather than the
  experimental task, it should also be possible to
  manipulate RT without affecting the activity in
  question.
• Use neural activity associated with lexical
  processing to address questions about lexical
  processing and structure that are not easy to
  investigate behaviorally.

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(No Transcript)
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Behavioral inhibition

• Words are sometimes harder to recognize when they
  are preceded by similar sounding words (e.g.
  Soto-Faraco, Sebastián-Gallés Cutler)

slower when preceded by
SPINACH
SPIN
than when preceded by
MUFFLER
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Behavioral inhibition

• Words are sometimes harder to recognize when they
  are preceded by similar sounding words (e.g.
  Soto-Faraco, Sebastián-Gallés Cutler, 2001)

slower when preceded by
SPINACH
SPIN
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Inhibited activation
activation level
time
time
RT
SPIN
s p i n a c h
PRIME
TARGET
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Alternative Inhibited recognition
activation level
time
RT
SPIN
s p i n a c h
PRIME
TARGET
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Mechanisms of recognition

• Inhibited activation
• Mismatching candidates are suppressed below their
  resting level
• Inhibited recognition
• Mismatching candidates are rejected simply
  because they receive less excitation from the
  input
• BUT make similar behavioral predictions

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Timing of activation
INHIBITED ACTIVATION
INHIBITED RECOGNITION
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M350
a tool for investigating inhibitory mechanisms
INHIBITED ACTIVATION
INHIBITED RECOGNITION
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Materials

• Crossmodal priming paradigm (materials from
  Gonnerman 2000)
• SOA Duration of prime
• Task Lexical decision

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Materials

• Two types of phonological similarity
• (embedded in a larger experiment)

1. ONSET-MATCHING
2. NON-ONSET-MATCHING
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Materials

• Two types of phonological similarity
• (embedded in a larger experiment)

• Would the M350 show inhibition or priming?
• If inhibition, activation is inhibited.
• If priming, RT inhibition originates in
  competition.

1. ONSET-MATCHING
2. NON-ONSET-MATCHING
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Materials

• Two types of phonological similarity
• (embedded in a larger experiment)

1. ONSET-MATCHING
2. NON-ONSET-MATCHING
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Results
n21
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Results
n21
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Results
n21
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Results
n21
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Results
n21
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Same behavior but different neurophysiological
effects
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Same behavior but different neurophysiological
effects

• Not all competitors are treated the same
• Some undergo complete deactivation

• Which ones?
• Onset-matching ones?
• Embedded ones?

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Asymmetry in mediated semantic priming (Isel and
Bacri 1999)

• If only onset-matching entries are suppressed,
  asymmetry is predicted

• If embedded words were suppressed, priming
  should fail in both cases

trombone RIB PRIMING (via BONE) cargo
BUS NO PRIMING (via CAR)
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The rest of the conditions (Gonnerman 1999)

• semantic idea-notion
• transparent morphological teacher-teach
• opaque morphological dresser-dress
• pseudoaffixed corner-corn

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Semantic idea-notion


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Transparent morphological teacher-teach



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Opaque morphological dresser-dress

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Pseudoaffixed corner-corn
p 0.06
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Opaque morphological dresser-dress



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Pseudoaffixed corner-corn





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Karen