Types of Linguistic Theories Prescriptive prescriptive linguistics is an oxymoron Prescriptive grammar how people ought to talk Descriptive provide account of syntax of a language Descriptive grammar ID: 626521
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Slide1
Chapter 5
Morphology and Syntax in NeurolinguisticsSlide2
Types of Linguistic Theories
Prescriptive
: “prescriptive linguistics” is an oxymoron
Prescriptive grammar:
how people ought to talk
Descriptive
: provide account of syntax of a language
Descriptive grammar
: how people do talk
often appropriate for NLP engineering work
Explanatory
: provide principles-and-parameters style account of syntax of (preferably) several languagesSlide3
What is morphology?
Morphology studies the structures of words in a language (root, affix – prefix and suffix)
Example:
Nation National International Internationalization
Fire fired firing Slide4
Linguistic Units
Phonetics – phoneme (allophones), distinctive features
Phonology – phoneme, distinctive features, syllable …
Morphology – morpheme (unit of meaning)
Bound morpheme: a morpheme that cannot stand alone as an independent word. Example: -MENT in ship-MENT.
Free morpheme: a morpheme that can stand alone as an independent word. Example: car, dog, pick. Slide5
Morphological analysis exercise
Online exercise:
http://www.arts.uwaterloo.ca/~raha/306a_web/morphological.swfSlide6
Problematic
cases
Receive reuse
Deceive deconstruction
Perform deformSlide7
Allomorphs
im - plausible
im - mature
im-possible
in
-
competent
il
- legal
ir
- relevantSlide8
Word formation rules
-Derivation
-Compounding
-InflectionSlide9
What is syntax?
Syntax is the study of the principles and rules for constructing sentences in natural languages.
While morphology examines how the smallest units of meaning are formed into complete words, syntax looks at how the words are formed into complete sentences.Slide10
What is Syntax Not?
Phonology: study of sound systems and how sounds combine
Morphology: study of how words are formed from smaller parts (morphemes)
Semantics: study of meaning of languageSlide11
What is Syntax? (2)
Study of structure of language
Specifically, goal is to relate an interface to morphological component to an interface to a semantic component
Note: interface to morphological component may look like written text
Representational device is
tree structureSlide12
The Big Picture
Empirical Matter
Formalisms
Data structures
Formalisms (e.g., CFG)
Algorithms
Distributional Models
Maud expects there to be a riot
*Teri promised there to be a riot
Maud expects the shit to hit the fan
*Teri promised the shit to hit the fan
Linguistic Theory
?
?
?
?Slide13
Syntax: Why should we care?
Grammar checkers
Question answering
Information extraction
Machine translationSlide14
key ideas of syntax
Constituency
(we’ll spend most of our time on this)
Subcategorization
Grammatical relations
Movement/long-distance dependencySlide15
What About Chomsky?
At birth of formal language theory (comp sci) and formal linguistics
Major contribution: syntax is
cognitive
reality
Humans able to learn languages quickly, but not all languages
universal grammar
is biological
Goal of syntactic study: find universal
principles
and
language-specific
parameters
Specific Chomskyan theories change regularly
General ideas adopted by almost all contemporary syntactic theories (“principles-and-parameters-type theories”)Slide16
Basic syntactic structure
Subject + Predicate
Subject of a sentence is the person, place, object, idea, event that is doing or being something.
Predicate is the completer of a sentence.
Example:
The glacier melted.
The glacier has been melting.
The glacier melted, broke apart, and slipped into the sea.
Interesting cases
Flying planes can be dangerous.
Colorless green ideas sleep furiously. Slide17
Syntactic TreesSlide18
Syntactic rules
Wh
-movement
He buys bread.
Who buys bread?
What does he buy?
He buys what?
I wonder what he bought.
*I wonder he bought what.
*I wonder what did he buy.Slide19
Types of syntactic constructions
Is this the same construction?
An elf
decided
to clean the kitchen
An elf
seemed
to clean the kitchen
An elf cleaned the kitchen
Is this the same construction?
An elf
decided
to be in the kitchen
An elf
seemed
to be in the kitchen
An elf was in the kitchenSlide20
Types of syntactic constructions (ctd)
Is this the same construction?
There is an elf in the kitchen
*There
decided
to be an elf in the kitchen
There
seemed
to be an elf in the kitchen
Is this the same construction?
It is raining/it rains
??It
decided
to rain/be raining
It
seemed
to rain/be rainingSlide21
Types of syntactic constructions (ctd)
Is this the same construction?
An elf
decided
that he would clean the kitchen
* An elf
seemed
that he would clean the kitchen
An elf cleaned the kitchenSlide22
Types of syntactic constructions (ctd)
Conclusion:
to seem:
whatever is embedded surface subject can appear in upper clause
to decide:
only full nouns that are referential can appear in upper clause
Two types of verbsSlide23
Types of syntactic constructions: Analysis
an elf
S
NP
VP
V
to decide
S
NP
VP
V
to be
PP
in the
kitchen
S
VP
V
to seem
S
NP
VP
V
to be
PP
in the
kitchen
an elf
an elfSlide24
Types of syntactic constructions: Analysis
an elf
S
NP
VP
V
decided
S
NP
PRO
VP
V
to be
PP
in the
kitchen
S
VP
V
seemed
S
NP
VP
V
to be
PP
in the
kitchen
an elfSlide25
Types of syntactic constructions: Analysis
an elf
S
NP
VP
V
decided
S
NP
PRO
VP
V
to be
PP
in the
kitchen
S
VP
V
seemed
S
NP
VP
V
to be
PP
in the
kitchen
an elfSlide26
Types of syntactic constructions: Analysis
an elf
S
NP
VP
V
decided
S
NP
PRO
VP
V
to be
PP
in the
kitchen
S
NP
i
VP
V
seemed
S
NP
VP
V
to be
PP
in the
kitchen
an elf
t
iSlide27
Agrammatism
in aphasia
Traditional theory
Broca’s aphasia
Lesion site: Broca’s area in the inferior frontal region (Brodmann’s areas 44 and 45)
Symptoms characterized by
agrammatism
: Sparse speech.
Parients
tend to speak in very short, simple sentences or even shorter structures mainly containing nouns, main verbs and adjectives, but omitting most grammatical morphemes (such as noun and verb inflections) and so-called function words (conjunctions, articles, etc
.).Slide28
Paragrammatism
in aphasia
Traditional theory
Wernecke’s aphasia
Lesion site: Wernecke’s area in the superior temporal region (Brodmann’s areas 21 and 22)
Symptoms (word salad): fluent (oftentimes nonsense) speech. Lacks semantic coherence. Patients tend to speak with frequent self-interruptions, restarts, and circumlocutions, caused by their anomic problems (word-finding difficulties). Grammatical frames appear unaffected. Slide29
Problems in traditional theory
1.
The relationship between comprehension and production.
Are disorders of
grammar central, thus affecting both comprehension and production, or can
production be selectively disturbed while comprehension is maintained?
2.
The relationship between
agrammatism
and
paragrammatism
. Are
agrammatism
and
paragrammatism
really two fundamentally different phenomena or are they different surface manifestations of grammatical problems that are basically similar but are accompanied by different sets of additional symptoms in Broca’s and Wernecke’s aphasia?Slide30
Some
findings in aphasia
Morphology
1. Free grammatical morphemes (e.g., function words) tend to be omitted, but they are sometimes substituted as well.
2. Bound grammatical morphemes (e.g., inflectional endings) are rarely omitted, but are often substituted.Slide31
Syntax
1.
Agrammatism
(defined only by short phrase length and slow speech rate) seems to exist in most languages and is usually combined with reduced variety in syntax.
2. There is great variation between languages, but a selective vulnerability of grammatical inflections and function words can be found in all aphasics.
3. A substantial number of main verbs are omitted. Many studies give verbs a central role in the formation of the syntactic structure of utterances.Slide32
Morphological and syntactic complexity interact
Morphological and syntactic complexity interact in making a grammatical structure hard to process. Processing conditions seem to matter in that
a. simplification is attempted, and
b. complex structures tend to break down and contain many errors. This points to “access problems” as a likely underlying cause.Slide33
Theories on
agrammatism
Mapping hypothesis
The main problem in
agrammatic
comprehension is the
mapping of
syntactic representations into semantic representations, whereas syntactic parsing is not affected.
Good: syntactic processing
Good: canonical order processing
Bad:
lexico
-inferential processing of thematic roles
Example: The man was eaten by the frog.Slide34
Adaptation Hypothesis (Ease of effort)
In this framework,
agrammatism
involves adaptation to the timing deficit. This adaptation to the “reduced temporal window” leads to three types of strategies:
1. simplification: reduced variety, isolated phrases (as a result of preventive adaptation or economy of syntactic computation);
2. restart: faster activation by restarting and profiting from the activation of the first attempt (corrective adaptation);
3. slow rate of speech.Slide35
The Trace Deletion Hypothesis and Tree-pruning Hypothesis (Syntactic Trees).
The aphasic disturbance specifically affects
traces, or the empty positions that are left when movement transformations are performed.
When a node is impaired, the tree is “pruned” upward, so that all nodes above it become inaccessible.