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Sentence Processing: Overview
Basic Terms
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Lexical Category: Parts of speech such as noun, verb, adjective, adverb,
preposition, conjunction, pronoun, determiner etc.
Phrasal category: a category whose members are composed of one or more words
that form a phrase such as noun phrase, verb phrase, preposition phrase, adjective
phrase etc.
Phrase structure rule: rule that shows the possible (grammatical) relationships
between phrasal categories and the words (e.g. ‘NP  Det N’ says that the phrasal
category noun phrase is composed of a determiner and a noun)
In general, XP  X Y Z means X phrase (= XP) consists of (= ) X, Y, and Z.
Simplified phrase structure rules of English:
S’  C S
S  {NP/S’} (T) VP
VP  (AP+) V ({NP/S’}) (PP+)(AP+)
NP  (D) (AP+) N (PP+)
PP  P (NP)
AP  (AP) A
XP  XP conj XP
X  X conj X
S’: sentence with conjunction
C: conjunction
T: Tense
AP: adjective phrase
PP: preposition phrase
+: can occur more than once
 : consists of
S: sentence
VP: verb phrase
NP: noun phrase
{}: can occur optionally
 Two major properties of the phrase structure rules:
1) Recursivity: The rules we have written here have a very important property. Notice
the following thing: The S rule has a VP under it. Similarly, the VP rule can taken
an (S’) under it This means that the two rules can forma loop and repeat endlessly:
Fred said that Mary believes that Susan wants that Peter desires that … etc.
2) Structural Ambiguity: a prepositional phrase (PP) can be generated from NP rule
or VP rule. Given a PP (i.e. with a telescope), in a verb phrase “saw the man with a
telescope”, it is not sure whether the PP is generated as a part of VP, or as a part of
an NP (attachment problem, ambiguous modification relation).
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5.
6.
The boy laughed.
The man in the kitchen drives a truck.
Pat and Leslie raised llamas.
Robin drove her car into a tree.
Many executives eat at really fancy restaurants.
Many retired workers spend their time on relaxing hobbies.
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Thematic relations: Who-does-what-to-whom relations
a. Thematic role: the set of semantic roles in a sentence that conveys
information about who is doing what to whom, as distinct from the syntactic
roles of subject and object. Examples include agent and theme.
i. agent: the thematic role describing the entity that instigates an action
ii. theme: the thing that is being acted upon or being moved
Sentence Processing (Parsing) and ambiguous sentences
1. Sentence Processing is a process of
a. grouping words into a unit; and
b. connecting (attaching) the unit to another unit
2. Sentence processing concerns the processes where people make sense out of strings
of words (i.e. comprehend sentences).
3. Studying people’s linguistic behaviors in processing ambiguous sentences suggest
certain facts about sentence processing. Consider the following sentences:
1. The old man the boat.
2. The boat floated downstream sank.
3. The daughter of the king’s son admired himself.
4. The florist sent the flowers was pleased.
5. The cotton clothing is made from grows in Mississippi
6. They told the boy the girl met the story.
7. The spy saw the cop with a telescope.
8. The horse raced the barn fell.
4. Ambiguity (more than one choice)
a. Lexical ambiguity: one word with two different meanings
e.g. John went to the bank after lunch yesterday.
b. Structural ambiguity (attachment ambiguity, Part-of-speech ambiguity)
i. Local (temporary) ambiguity
e.g. The horse raced past the barn fell.
ii. Global ambiguity
e.g. I saw the man with binoculars.
Consider the following sentence
The cop informed the motorist that he had noticed, to avoid overtaking the school bus.
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o The cop informed the motorist ...
o ... that he had noticed ... (ambiguity region)
o ... to avoid overtaking the school bus (disambiguation region)
Decision Principles
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How many choices are taken? One or more? In what manner?
Serial Parsing: by choosing just one analysis
Parallel Parsing: by projecting all possible analyses of the ambiguous string
Minimal Commitment: by delaying making any decision about the analysis (wait-andsee)
5. See the chart (next page)
Information Use Principles
Constraints on Information Use: All the sources of information are available to the
processor equally immediately and likely? Or, a particular source information is only
available to the processor?
1. Modular model: Parsing is performed initially by a syntactic module that is not
influenced by higher-order contextual variables such as the meaning of the sentence or
by general world knowledge (Parsing is executed by a syntactic module, and these
contextual factors influence comprehension at a later stage)
2. Interactive Model: Syntax and semantics interact during the comprehension process.
We simultaneously use all available information in our initial parsing of a sentence:
syntactic, lexical, discourse, as well as nonlinguistic, contextual information.
Theoretical Proposals and evaluation
Decision Making
Principle
Information Use
One choice
Serial
Parsing
Deterministic
Probabilistic
More than
one choice
Parallel
Parsing
Unbiased
Weighted
No choice
Minimal
Commitment
Reading Time Prediction @
ambiguous
disambiguating region
In the case of
In the case of
correct choice incorrect choice
Modularity Interactive
X
X
No effect
No effect
X
X
Empirical Evidence a
Slowed-down
Slowed-down
No effect
Slowed-down
Faster
--
--
No effect
No effect
Slowed Down