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Some putative hallmarks of human
language
Creativity of linguistic meaning
•  ! 50k words in a language
–  Open class words
•  Concrete: dog, woman, house
•  Abstract: belief, believe, jealousy
–  Closed class words
•  the, of, from, without, …
•  Infinitely many combinatory meanings, including
impossible ones:
–  I met a green cyclops in the garden today.
–  John thought Jane knew that I met a green cyclops in the garden
today.
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Human linguistic creativity and
semantic and pragmatic operations.
•  Semantic combinations can be fickle
–  The blue …
•  sky, bruise, eyes, ribbon, water of the Caribbean.
•  And metaphorical
–  The meeting was a zoo.
•  And shaped by pragmatics
–  Do you have the time? And can you pass the salt?
–  It’s cold in here.
Human linguistic creativity and
grammatical structure
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Grammatical knowledge is represented
independently of meaning.
Colorless green ideas sleep furiously.
Furiously sleep ideas green colorless.
Human linguistic creativity and
grammatical structure
•  Grammar changes meaning
–  The dog bit the man.
–  The man bit the dog.
–  The man was bitten by the dog.
–  The dog was bitten by the man.
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And grammar allows us to combine
“infinitely”
•  Bob thinks I told Jane to order Sarah to fire the new guy.
Recursion
•  S ! NP VP
•  NP ! Det N S
•  VP ! V NP
•  “the man that the cops saw was a drug dealer”
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Influential idea in the cognitive
science of language:
human brains are computational
systems for processing
generative grammars.
Classical view of parsing in NLP:
Parser + Grammar
The student forgot the answer.
Parser
S
Grammar: !
S ! NP VP !
NP ! D N!
VP ! V NP!
VP ! V S!
VP ! V !!
VP ! V NP NP
!
V ! {forgot, ate} !
N ! {student, answer}!
NP
VP
NP
!!
D
N
V
D
N
The student forgot the answer.
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Levels of Representation and Processing
Semantics: EXAMINED [DETECTIVEAGENT, EVIDENCETHEME]
Agent and Theme
are “thematic roles”
(Who did what to whom?)
S
Syntactic
structure:
NP
VP
NP
D
N
V
D
N
The detective examined the evidence.
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Humans are limited-resource
language processors
•  Chomsky’s distinction between
–  “competence”: knowledge of the abstract
rules of the grammar
–  “performance”: the ability to apply those rules
to linguistic input in producing or
comprehending a sentence
•  Limited by memory, attention, etc…
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just because it’s grammatical
doesn’t mean we can understand it
•  The dog that the rat that the cat ate bit died
Center embedding.
•  The dog that the rat that the cat ate bit died
–  The dog
died
–
that the rat
bit
–
that the cat ate
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Center embedding
isn’t always this difficult
•  The patient that the doctor I know treated recovered from the illness.
•  The airstrip that the plane the pilot flew landed at was tiny.
•  The gazelle that the cheetah the tourists watched hunted escaped into the
forest.
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Ambiguity
Lung Cancer in Women Mushrooms
Teacher Strikes Idle Kids
Stud Tires Out
Shot Off Woman's Leg Helps Nicklaus to 66
Enraged Cow Injures Farmer with Axe
Miners Refuse to Work after Death
Squad Helps Dog Bite Victim
Juvenile Court Tries Shooting Defendant
Stolen Painting Found by Tree
Killer Sentenced to Die for Second Time in 10 Years
Drunk Drivers Paid $1,000 in 1984
Grandmother of Eight Makes Hole in One
Two Convicts Evade Noose, Jury Hung
16!
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Garden Path Errors and syntactic
ambiguity
•  The horse raced past the barn fell.
•  The horse was raced past the barn (by somebody). CORRECT
INTERPRETATION
•  The horse fell.
•  The horse raced past the barn.
•  The barn fell.
WRONG
INTERPRETATION
•  The cotton clothing is made of grows in Mississippi.
•  The old man the boat.
•  We painted the wall with cracks.
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The modularity of syntactic processing?
•  Language understanding is controlled by a
syntactic processing system, which:
–  Builds phrase structural representations (parses)
–  Is fast and automatic
–  Is functionally independent from outside influences
(such as semantic or pragmatic processing).
–  Operates with limited resources
– Precedes and guides semantic
interpretation
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Fodor (1983): many mental functions are accomplished
by “modules”, which fulfill certain properties (“at least to
some interesting extent”):
1.
2.
3.
4.
5.
6.
7.
8.
9.
Domain specificity
Vulnerable to selective breakdown
Informational encapsulation
Obligatory firing
Fast, probably due to 3 and 4 above
Shallow outputs, the output of modules is very simple
Limited accessibility
Characteristic ontogeny, there is a regularity of development
Fixed neural architecture
Syntax First models of syntactic ambiguity
resolution (e.g., Frazier, 1987; 1989).
The witness examined …
•  Stage 1: Syntactic commitment (strictly serial)
–  Minimal processing of input word (e.g., D, N, V, etc.)
–  Knowledge of phrase structure grammar
–  Syntactic processing heuristics (e.g., avoid complexity)
•  Stage 2: Semantic interpretation
–  Assign thematic roles (e.g., Agent & Theme)
–  Evaluate and revise if implausible.
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The Garden-Path model: syntax first
(Frazier, 1987; 1989).
•  Initial commitments based on limited syntactic
information:
–  Coarse-grained lexical input: POS-only
–  Temporary ambiguities resolved by syntactic heuristics
•  Minimal Attachment
•  Late Closure
•  Second stage assigns thematic roles (Agent,
Theme, etc)
–  Stage 1 Commitments can be revised in second stage.
•  Predicts frequent and highly uniform pattern of
misanalysis.
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