SYNTAX 6
NOV 20, 2015 – DAY 36
Brain & Language
LING 4110-4890-5110-7960
NSCI 4110-4891-6110
Fall 2015
11/20/15
Brain & Language - Harry Howard - Tulane University
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Course organization
• Schedule:
• http://www.tulane.edu/~howard/BrLg/t1-Intro.html#schedule-oftopics
• Today's chapter:
• http://www.tulane.edu/~howard/BrLg/t19-aIFG.html
• Fun with https://www.facebook.com/BrLg15/
• Quiz on Monday will be in class & on Blackboard.
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Brain & Language - Harry Howard - Tulane University
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Grades
Q1
Q2
Q3
Q4
Q5
Q6
Q7
MIN
6
5
5
4
7
3
4
AVG
9.0
8.8
8.8
8.4
9.2
7.5
8.7
MAX
10
10
10
10
10
10
10
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Brain & Language - Harry Howard - Tulane University
COMBINATORIAL NET 2
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The lexical interface
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Models of sentence processing
Traditional generative model
More recent interactive model
• A separate mental module
• There is no separate module
parses sentences just like
we just did.
• Lexical access happens
first.
• Then one syntactic
hypothesis is considered at
a time.
• There is no influence of
meaning.
for parsing
• Lexical access, syntactic
structure assignment, and
meaning assignment
happen at the same time (in
parallel).
• Several syntactic
hypotheses can be
considered at a time.
How to decide?
On-line processing
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Two types of processing
on-line
off-line
• Happens in real time.
• Happens after the fact.
• Instructions for an
• Instructions for an
experiment to test it:
experiment to test it:
• You will read a sentence,
• You will read a sentence.
one word at a time.
• Push a key after each word.
• Point to the picture that
describes it best.
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Brain & Language - Harry Howard - Tulane University
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The working memory needed for parsing …
… is part of a general purpose
working memory
• Individual differences in
working memory are
implicated in strategies for
understanding complex
spoken sentences.
… constitutes its own specialized
store of working memory.
• Some patients who share
severe deficits of general
purpose working memory
are still able to
understand complex
spoken sentences.
• Individual differences in
working memory are
usually not implicated in
on-line language
understanding.
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Brain & Language - Harry Howard - Tulane University
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Why?
• ‘Cognitive capacity’
• Low span readers only have enough capacity to process syntactic
cues; nothing is left over to process pragmatics => modular
processing (syntax first).
• High span readers have enough capacity to process syntactic cues
and pragmatics => interactive processing (all cues considered
simultaneously).
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Brain & Language - Harry Howard - Tulane University
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Center embedding
9) The rat the cat hunted nibbled the cheese.
The rat which the cat hunted nibbled the cheese.
10) The rat the cat the dog chased hunted nibbled the cheese.
The rat which the cat which the dog chased hunted nibbled the cheese.
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How might this be processed?
The parser encounters …
the rat > look for a predicate to supply a
thematic role …
the cat > wait, put the previous search on
hold & look for another predicate to supply
a thematic role …
the dog > wait, put the previous search on
hold & look for yet another predicate to
supply a thematic role …
Ok, now I am lost.
thematic role for ‘the dog’
thematic role for ‘the cat’
thematic role for ‘the rat’
push-down stack
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Brain & Language - Harry Howard - Tulane University
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‘Edge’ embedding does not create this problem
i) The dog chased the cat that hunted the rat that nibbled the cheese.
ii) The dog that chased the cat that hunted the rat that nibbled the cheese was a dachshund.
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Brain & Language - Harry Howard - Tulane University
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Interim conclusion
• The limit on center embedded is 2.
• Given that Miller’s number is much larger, it would appear
that there is a working memory specialized for parsing.
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Brain & Language - Harry Howard - Tulane University
Ockham’s razor, simplicity, economy
lex parsimoniae
• Ockham’s razor is a
principle that generally
recommends selecting
from among competing
hypotheses the one
that makes the fewest
new assumptions.
• Einstein-ish: “Make
things as simple as
possible, but not
simpler.”
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Brain & Language - Harry Howard - Tulane University
Filler-gap constructions
though the gap is also called a trace
• How to get rid of the leprechauns
a. Mary bought a book for John.
b. Which booki did Mary buy ____i for John?
c. John asked Mary about a student.
d. Which studenti did John ask Mary about ____i ?
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Brain & Language - Harry Howard - Tulane University
SYNTAX 4
Sentence comprehension and syntactic parsing
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Cross-modal priming & trace reactivation
sentence presented auditorily; prime & probe visually
prime
16) Which booki did the harassed parent almost purchase ti for her child?
faster for related
probe:
library/
vehicle
same for both
faster for related
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Gaps/traces in relative clauses
• The dog chased the cat.
• Subject relative clause
• The dog that chased the cat … =
• The dogi that ti chased the cat …
• Object relative clause
• The cat that the dog chased … =
• The cati that the dog chased ti …
• Which one should be harder to process?
• The object relative clause, because the relationship between the
real filler (the cat) and the gap has to ignore the potential filler (the
dog).
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Brain & Language - Harry Howard - Tulane University
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Self-paced reading & subject-object
• The data: reading time for us
20a) My brother wanted to know if Ruth will bring us home to Mom at Xmas.
20b) My brother wanted to know who will bring us home to Mom at Xmas. =
20b) My brother wanted to know whoi ti will bring us home to Mom at Xmas.
20c) My brother wanted to know who Ruth will bring us home to at Xmas. =
20c) My brother wanted to know whoi Ruth will bring us home to ti at Xmas.
• Which one should be slowest?
• (20c) because us is a possible site for the gap/trace of who.
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Brain & Language - Harry Howard - Tulane University
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NEURAL IMAGING & ON-LINE
SENTENCE PROCESSING
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Dipoles, 3
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Result of electrical currents: EEG
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Scalp EEG
• Scalp EEG is collected
from tens to hundreds
of electrodes
positioned on different
locations at the surface
of the head.
• EEG signals (in the
range of millivolts) are
amplified and
digitalized for later
processing.
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Brain & Language - Harry Howard - Tulane University
The 10-20 system
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• The "10" and "20" refer to the fact that the
actual distances between adjacent electrodes
are either 10% or 20% of the total front-back
or right-left distance of the skull.
• Each site has a letter to identify the lobe and a
number to identify the hemisphere location.
The letters F, T, C, P and O stand for Frontal,
Temporal, Central, Parietal, and Occipital,
respectively.
•
Note that there exists no central lobe, the "C"
letter is only used for identification purposes only.
• A "z" (zero) refers to an electrode placed on
the midline.
• Even numbers (2,4,6,8) refer to electrode
positions on the right hemisphere, whereas
odd numbers (1,3,5,7) refer to those on the left
hemisphere.
• Two anatomical landmarks are used for the
essential positioning of the EEG electrodes:
first, the nasion which is the point between the
forehead and the nose; second, the inion
which is the lowest point of the skull from the
back of the head and is normally indicated by
a prominent bump.
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Brain & Language - Harry Howard - Tulane University
Semantic vs. syntactic ERPs
• The data
a. The boat sailed down the river and sank.
b. The boat sailed down the river and ate.
c. The boat sailed down the river sank.
• How would you characterize these sentences?
a. well-formed
b. semantically anomalous
c. syntactically anomalous
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Brain & Language - Harry Howard - Tulane University
ERPs to last verb in sentence
What does the
scale mean?
Where does
the dashed
line diverge
most from the
solid line?
Where does
the dotted line
diverge most
from the solid
line?
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What do they do?
• N400
• A temporarily localized increase in processing load caused by a
discrepancy between the meaning of a word and its sentential
context.
• P600
• A sustained effort to reinterpret or re-parse a garden path sentence.
• However, these two may be too slow to reflect modular
lexical or syntactic processing.
• So lets look at a faster ERP.
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Brain & Language - Harry Howard - Tulane University
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The early left anterior negativity
N150 or ELAN
Basic flaws in phrase structure:
The shirt was on the hanger.
The shirt was ironed.
*The shirt was on ironed.
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Modular vs. interactive processing
Modular: an error found early could turn off additional processing.
Interactive: errors should add up.
English example
(orig. German)
Phrase
structure
obeyed
Argument
structure
obeyed
N150
N400
P600
The old cat slept in
the garden and …
✔
✔
--
--
--
The cat old slept in
the garden and …
✖
✔
✔
✖
✔
The old cat slept
the garden and …
✔
✖
✖
✔
✔
The cat old slept
the garden and …
✖
✖
✔
✖
✔
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Final project
• Improve a Wikipedia article about any of the topics
mentioned in class or any other topic broadly related to
neurolinguistics.
• Write a short essay explaining what you did and why
you did it.
• Print the article before you improve it, highlighting any
subtractions.
• Print the article after you improve it, highlighting your
additions.
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Brain & Language - Harry Howard - Tulane University
NEXT TIME
P10 on Blackboard & in class
More syntax
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