Transcript Powerpoint for syntax 2

SYNTAX 2
NOV 11, 2015 – DAY 32
Brain & Language
LING 4110-4890-5110-7960
NSCI 4110-4891-6110
Fall 2015
11/11/15
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 before Thanksgiving will be in class & on
Blackboard.
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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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COMBINATORIAL NET 2
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The lexical interface
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The parts of speech/syntactic categories
• Major/content categories
• noun
• verb
• adjective
• adverb
• preposition/postposition?
• Minor/functional categories
• determiner: article, quantifier, demonstrative
• pronoun
• negation
• conjunction: coordinating, subordinating
• auxiliary verb?
• Interjection
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A fragment of a grammar of English
• “A grammar is an explicit set of rules for distinguishing the
well-formed sentences of a language from those that are
ill-formed (ungrammatical).”
• We have already seen a fragment of a grammar of
English:
S → NP VP
② VP → V NP
①
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What is syntactic processing?
• “Narrowly defined, syntactic processing involves the
assignment of syntactic structure to word strings that
qualify as a ‘sentences’”, e.g. "Mary kissed John".
• [S [NP Mary] [VP kissed [NP John]]]
S
NP
Mary
V
kissed
VP
NP
John
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But …
• … we very often utter incomplete sentences:
a) Who kissed John?
b) Mary.
c) What did Mary do?
d) Kiss John.
• So the missing information can be filled in by the context:
a) Who kissed John?
b) [S Mary [VP Ø]]
c) What did Mary do?
d) [S [NP Ø] [VP kiss John]]
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Compositionality
• Compare these next two sentences:
1. Mary kicked the mule.
2. Mary kicked the bucket.
• #2 has two readings
a. Mary applied force to the bucket with her foot.
b. Mary died.
• In the (a) reading, the sentence means what the sum of its
words mean; in the (b) reading, it means something special,
not predictable from the individual words.
• This happens in morphology, too:
a.
b.
the past tense of depart: departed
the past tense of go: *goed, went
• We call the (a) readings compositional, while the (b) readings
are non-compositional or lexical.
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SYNTAX 2
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Another example
• “A cat is on the couch.”
• We need to augment our grammar:
③ NP → Det N, where Det is one of {a(n), the, some}
④ VP → V PP
⑤ PP → P NP, where P is one of {on, in, at, by, etc.}
• Write down the syntactic structure for this example:
• [S [NP a cat] [VP is [PP on [NP the couch]]]]
S
VP
NP
a cat
V
is
PP
on the couch
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The problem of assigning syntactic
structure in real time
• So, how did you do that?
• You assigned a syntactic (or structural) description to the
sentence, following the rules of the grammar, presumably
from left to right, which is a process known as performing
a derivation.
• It is also known as parsing the sentence:
• "to state the parts of speech in a sentence”, 1550s,
• verb use of M.E. pars (n.) "part of speech" (c.1300),
• from O.Fr. pars, pl. of part "part”,
• from L. pars (see part (n.)) in school question, Quae pars orationis?
"What part of speech?"
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Start with the first word
“A cat is on the couch.”
• A – what do we know about it?
• Determiner, indefinite, singular = Lexical Access and Feature Retrieval
(LAFR)
• What does our grammar tell us about a determiner (Det)?
• It is followed by a noun, so let’s look for one to the right.
• And by the way, it should be singular, to agree with the determiner.
• Cat – what do we know about it?
• Noun, singular (LAFR)
• We also know a lot about the meaning of ‘cat’, but this theory of syntax
assumes that meaning is not relevant to the parse.
• What does our grammar tell us about Det+N?
• That they form an NP, so let’s merge them into one:
• [NP [Det a] [N cat]]
• What does our grammar tell us about NP?
• It is followed by a (tensed) verb, so let’s seek one to the right.
• Do the rest of the derivation yourself.
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Models of sentence processing
• Traditional generative model
• A separate mental 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.
• More recent interactive model
• There is no separate module 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?
• Agrammatism
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The lexical interface
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But first, a review: Thematic roles
• What is a thematic role?
• List of roles
• AGENT
• EXPERIENCER
• THEME
• GOAL
• SOURCE
• LOCATION
• RECIPIENT
• INSTRUMENT
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Review: Thematic roles
a. John gave a tomato a. AGENT gave THEME
to Mary.
b. John gave Mary a
tomato.
c. A brilliant idea
occurred to Mary.
d. Mary hates
tomatoes.
to RECEIPIENT
b. AGENT gave
RECEIPIENT THEME
c. THEME occurred to
EXPERIENCER
d. EXPERIENCER hates
THEME
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Syntax vs pragmatics
• How about these?
1) The cop arrested the teenagers.
2) The teenagers arrested the cop.
• How can we tell the difference?
• Syntactic info:
•
•
•
•
•
Subject agrees with verb;
subject precedes verb;
subject tends to be AGENT.
Direct object follows verb;
direct object tends to be THEME.
• Pragmatic info:
• Police are typical arresters;
• teenagers are typical arrestees.
• Note that syntax overrides pragmatics in (2).
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The two main aphasias
Ingram p. 49
Broca’s
Wernicke’s
• C: What brought you to the
• C: What brings you to the
hospital?
• P: yes … ah … Monday …
ah … Dad … Peter Hogan,
and Dad … ah … hospital …
and ah … Wednesday …
Wednesday … nine o’clock
and ah Thursday … ten
o’clock … doctors two …
two … an doctors and … ah
… teeth … yah … and a
doctor an girl … and gums,
an I.
hospital?
• Boy, I’m sweating, I’m awful
nervous, you know, once in
a while I get caught up, I
can’t mention the tarripote, a
month ago, quite a little, I’ve
done a lot well, I impose a
lot, while on the other hand,
you know what I mean, I
have to run around, look it
over, trebbin and all that sort
of stuff.
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Agrammatic aphasia (agrammatism)
One aspect of Broca’s aphasia
• Agrammatic aphasiacs may overlook agreement, but they
are still sensitive to word order.
• However, they often rely on pragmatics, so they may
understand (2) to mean (1):
1)
2)
The cop arrested the teenagers.
The teenagers arrested the cop.
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Public service announcement
• What is a Ponzi scheme?
• How is the passive voice formed?
• (someone) ended the Ponzi scheme quickly.
• AGENT
THEME
• The Ponzi scheme was ended quickly
• http://en.wikipedia.org/wiki/English_passive_voice
• Two sentences later, Madoff said, "When I began the Ponzi scheme, I
believed it would end shortly, and I would be able to extricate myself,
and my clients, from the scheme." As he read this, he betrayed no
sense of how absurd it was to use the passive voice in regard to his
scheme, as if it were a spell of bad weather that had descended on
him . . . In most of the rest of the statement, one not only heard the
aggrieved passive voice, but felt the hand of a lawyer: "To the best of
my recollection, my fraud began in the early nineteen-nineties."[9]
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Active vs. passive sentences
• Ask the patient to point
to the picture in which
• The dog bit the postman.
• The dog was bitten by
the postman.
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Reversible sentences
• Agrammatic aphasiacs find the following reversible active
sentences to be difficult to understand (75% accuracy):
3)
4)
The dancer applauded the actor.
The actor applauded the dancer.
• Reversible passive sentences are even harder (50%
accuracy):
5)
The actor was applauded by the dancer.
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Conclusions
• It may be that agrammatic aphasiacs rely on a rule of
thumb (heuristic) based on the canonical word order of
English or other frequent coincidences:
a)
b)
The NP which precedes the verb is assigned the thematic role of
AGENT.
The NP which follows the preposition by is assigned the thematic
role of AGENT.
• How they help
• (a) helps agrammatic aphasiacs understand reversible active
sentences.
• (a) and (b) conflict in reversible passive sentences, so agrammatic
aphasiacs do worse (they guess).
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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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NEXT TIME
More syntax
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