Download ERP Background 2 100406

Some Different Kinds of Things
You Know as English Speakers
 What’s wrong with each of the following?
!ort
sfort
bort
‘Twas brillig, and the slithy toves
Did gyre and gimbel in the wabe.
The cats won’t bake the meat loaf.
The cats won’t eating the meat loaf.
Some ERP Components Related to Language
N400 = ERP component related to meaning
- Bigger when word’s meaning doesn’t fit context
- Bigger for unfamiliar words
- May reflect amount of work required to
integrate with context
P600 = ERP component related to form
- Bigger when word property other than meaning
wrong or hard to process
- May be a type of P300
- Sometimes called Syntactic Positive Shift (SPS)
Can evoke both at once
- But not always as nice as here!
- Depending on size of each component
& timing of P600, can partially or
completely cancel each other out
Priming in Word Comprehension
 A word preceded by something related to it is
recognized & understood faster & more easily
tree
tree
blanket
job
doctor
nurse Faster
pencil
window
…
blanket
job
sports
nurse Slower
pencil
window
…
Coulson, Federmeier, Van Petten, & Kutas
(2005)
How do priming effects of lexical & sentence-level
context compare, & do they add or interact?
Stimulus Materials:
Congruous sentence plus highly associated word:
They were truly stuck, since she didn’t have a spare TIRE.
Congruous sentence but no associated word:
During the test, Ellen leaned over and borrowed my spare PENCIL.
Incongruous sentence plus highly associated word:
During the test, Ellen leaned over and borrowed my spare TIRE.
Incongruous sentence but no associated word:
They were truly stuck, since she didn’t have a spare PENCIL.
N400
Word pairs only
__ spare tire
… spare pencil
Word-in-sentence fx
__ …stuck… spare tire
…test… spare pencil
… …stuck … spare pencil
…test … spare tire
N400
Sentence context fx
__ …stuck… tire
…test… pencil
--- …stuck… pencil
…test… tire
Conclusions
 When a word is at the end of a sentence it fits
into well, it doesn’t matter much whether the
word right before it is an associate
 But out of sentence context, does matter
 So, by the end of a sentence, sentence context
trumps individual word associations
 Word associations (& word familiarity) have more
influence for words near the beginnings of sentences
Relationships Among Words in Sentences
“A University student charged with threatening to kill
the President via email was arrested Thursday,
following issuance of a complaint and warrant,
officials said.”
- Daily Illini, 2/27/94
Being Led “Down the Garden Path”
“A University student charged with threatening to kill
the President via email
Y
X
A Slightly More Subtle Example
“Marge Schott, managing partner of the Cincinnati
Reds, at first did not want to apologize for her
remark that Hitler‘was good at the beginning
but he just went too far’. Under pressure, she
finally said that she regretted her remarks
‘offended many people’.”
- NY Times, 7/21/96,
Tannen, I’m sorry, I won’t apologize
that
"Under pressure, she finally said that she regretted
^
her remarks 'offended many people'."
 What did she regret?
 Not her remarks, only their consequences
 But her choice of wording gives the appearance
of expressing regret for what she said
 Including an optional that would have made
it clearer
Temporary Structural Ambiguity
that
The referees warned the spectators against heckling the other team.
would probably get too rowdy.
^
Temporary ambiguity about relationship between
the Verb & the Noun after it
Is the noun
A Direct Object (DO) , or
Subject of an Embedded Clause?
Ambiguity arises because that optional (in English)
Verb Bias
Verbs differ in how often they're used in
particular sentence structures
Compare The referees warned the spectators ...
with The bus driver worried the passengers ...
warned = Direct-Object Biased Verb
worried = Clause-Biased Verb
In English, verb's most likely use guides
choices about initial interpretation of
words following it
Plausibility of Noun
as Direct Object
Plausibility of particular Verb + Noun
combinations varies
Compare The referees warned the spectators ...
with The referees warned the game ...
In English, plausibility of a particular
Verb + Noun combination sometimes
guides initial interpretation
Example Sentences
DO-Bias Verbs: (e.g., warned, discovered, heard ...)
The referees warned the spectators would probably get too rowdy.
The referees warned the game
would probably go into overtime.
Clause-Bias Verbs: (e.g., worried, realized, suspected ...)
The bus driver worried the passengers were starting to get annoyed.
The bus driver worried the tires
were starting to go flat.
EQ-bias Verbs: (e.g., regretted, predicted, knew, ...)
The senior senator regretted the decision had ever been made public.
The senior senator regretted the reporter had ever seen the report.
Results of Reading Time Studies
DO-Bias Verbs:
The referees warned the spectators would probably get too rowdy.
The referees warned the game
would probably go into overtime.
read slowly
Clause-Bias Verbs:
The bus driver worried the passengers were starting to get annoyed.
The bus driver worried the tires
were starting to go flat.
EQ-Bias Verbs:
read slowly
The senior senator regretted the decision had ever been made public.
The senior senator regretted the reporter had ever seen the report.
Verb Bias Rules (in English)!
 No effect of the Plausibility of the
Verb + Noun combination when the Verb
had a strong bias
 But Plausibility did have an effect when
the Verb had no bias
 So, the two factors interact, with
Verb Bias dominating the interaction
Limitation of Eyetracking Study
 Verb Bias & Plausibility both have the same
kind of effect on reading time
 People slow down when expectations based on either
kind of information are violated
 Are there other measures that would better
distinguish the two kinds of information?
 Yes, Event-Related brain Potentials (ERPs)
Stimulus Presentation
in ERP Study
Were the referees
expecting
overtime.
probably
referees
warned
would
game
The
into
the
go 1 a long game?
READY
QUESTION
Waveforms Starting at Temporarily Ambiguous Noun
Pz
DO-Bias Verbs (warned)
Plausible Noun:
The referees warned the spectators ...
Final
word
-6
-3
0
3
6
0
650
1300
1950
2600
Msec
spectators
Question
Waveforms Starting at Temporarily Ambiguous Noun
N400
Pz
DO-Bias Verbs (warned)
Plausible Noun:
The referees warned the spectators ...
Implausible Noun
The referees warned the game ...
-6
-3
0
3
6
0
650
1300
Msec
spectators/
game
1950
2600
Waveforms Starting at Temporarily Ambiguous Noun
DO-Bias Verbs (warned)
Plausible Noun:
The referees warned the spectators ...
Implausible Noun
The referees warned the game ...
N400
Pz
-6
-3
0
3
6
0
650
1300
1950
2600
1950
2600
Msec
spectators/
game
Clause-Bias Verbs (worried)
-6
-3
Plausible Noun:
The bus driver worried the passengers ... 0
3
Implausible Noun:
6
The bus driver worried the tires ...
0
650
1300
Msec
passengers/
tires
Waveforms Starting at Temporarily Ambiguous Noun
DO-Bias Verbs (warned)
Plausible Noun:
The referees warned the spectators ...
Implausible Noun
The referees warned the game ...
N400
Pz
-6
-3
0
3
6
0
650
1300
1950
2600
1950
2600
Msec
spectators/
P600
game
Clause-Bias Verbs (worried)
-6
-3
Plausible Noun:
The bus driver worried the passengers ... 0
3
Implausible Noun:
6
The bus driver worried the tires ...
0
650
1300
Msec
passengers/
tires
Summary
 In both reading time & ERP studies,
Verbs rule
 Difficulty at an Implausible Noun only after
a Verb that strongly predicts a Direct Object
 Difficulty at the disambiguating region
only after a Verb that strongly predicts a
Direct Object
Why do verbs rule?
 Principled reasons:
 They provide the most useful information
 Information about them may be simply retrieved,
while plausibility requires combining information
from multiple words
 More accidental reasons:
 They precede the critical nouns in these sentences
[ but, see Trueswell (1996) ]
 They generally appear early in English sentences,
leading English speakers to rely on them
Individual Differences
Osterhout (1997)
 Another harder kind of Garden Path sentence
that was
 The boat floated down the river sank.
^
 (The evidence examined by the lawyer turned out to be unreliable.)
 Stimulus Sentences
 The boat floated down the river and sank.
 The boat floated down the river and ate.
 The boat floated down the river sank.
Results Across All Subjects
N400
N400
P600
Results across just “P600 Subjects”
P600
Results across just “N400 Subjects”
N400
Individual Differences
 So, different people produce different ERP
components in response to exactly the same
stimuli !
 What does that mean both about
 How people respond to Garden Path sentences?
 & The nature of the different ERP components?
Kim & Osterhout (2005)
 Experiment 1 Stimulus Sentences
The hearty meal was devoured …
The hungry boys were devouring …
The hearty meal was devouring …
 N400 or P600 at devouring???
Experiment 1 Results
P600
P600
Experiment 2
 Stimulus Sentences
 The hearty meal was devoured …
 The dusty tabletops were devouring …
 The hearty meal was devouring …
 N400 or P600 at devouring after dusty tabletops???
Experiment 2 Results
N400?
P600
McGurk Effect
 Acoustic stimulus = /ba/
 Visual stimulus = face /ga/
 Hear /da/ = fused audiovisual stimulus
Mismatch Negativity (MMN)
(Naatanen & many colleagues)
 Deviant sound occurring infrequently in train of
frequent sounds
 Evokes a frontal negativity around 200 msec = MMN
 Initially thought to be purely auditory change
detection
 Source localization points to auditory cortex
 e.g., polarity reversal between Fz & Mastoids
Colin et al. (2002, 2005)
Auditory-only conditions show MMN
MMN
MMN
Visual-only conditions show no MMN
(as expected)
McGurk conditions do show MMN
/gi/Dev = hear /bi/, see /gi/
MMN
/bi/Dev = hear /gi/, see /bi/
MMN
Conclusions
 MMN tracks perception rather than simple
acoustics
 If generated in auditory cortex,
 Shows that visual info influences early sound
processing, probably in auditory cortex itself