Lecture_11_Language Processing Flashcards
Language Behavior
Using bits (symbols) and rules to communicate
Why interesting to cognitive psychologists?
- Unique to human species
- “Biological instinct”
- Highly structured signal, with specific rules
- Highly ambiguous
B.F. Skinner’s Verbal Behavior
Dominance of behaviorism
- Learning
- Imitation
- Reinforcement
Noam Chomsky
Nativist view of language (Innate)
- “Language is too complex to be learned through behaviorist principles only.”
- “Language knowledge and abilities are innate.”
Psycholinguistics
Cognitive psychology + linguistics (+ cognitive neuroscience)
- Cognitive & neural mechanisms in understanding, expressing, and learning language
- Language comprehension, production, acquisition
- Representation (storage) and real-time processing
Units of Language
Generated -> Stored
1. Phonemes
2. Words
3. Sentences
4. Discourse
Phonemes
- Phonology
- Combining speech sounds into words
Words
- Morphology
- Combining units of meaning into words (Affix) - Semantics: Assigning literal meaning
Sentences
- Semantics
- Assigning literal meaning - Syntax
- Combining words into sentences
Discourse
- Pragmatics
- Assigning situational meaning in context of discourse
Language Comprehension System
- Input
- Language perception: Sensory
- Word recognition: hear and retrieve
- Syntactic parsing: structure
- Semantic & pragmatic analysis
Ambiguities in Language
- Phonemes
- Words
- Sentences
- Discourse
Ambiguities in Language: Phonemes
- Coarticulation
- Variations in accents, talking speed, noise
- E.g. “Got a long list of Starbucks lovers”
- Phonemes do not appear as separate chunks
- Yet we usually perceive speech correctly
- The brain somehow extract the right word
Ambiguities in Language: Words
- Continuous stream of phonemes in the speech signal
- Segmentation problem
- More than one meaning
E.g. bat, bark - No clear space between words the brain has to determine the distinction
Ambiguities in Language: Sentences
- More than one meaning
- Due to ambiguous structure (syntax)
- E.g. Government plans to raise taxes failed
- Miners refuse to work after death
Ambiguities in Language: Discourse
- Meaning changes, depending on context
- Inferring meaning that wasn’t directly said or written
Speech Perception
- Categorical Perception
- Prior Knowledge & Contextual Cues
- Phoneme Restoration Effect
- Visual Cues: McGurk Effect
Categorical Perception
- To deal with coarticulation and immense variations in the speech signal…
- Categorical perception of phonemes helps us mentally perceive varied acoustic patterns as discrete, separate categories of phonemes
- The brain perception is categorical that helps solve ambiguity
Prior Knowledge & Contextual Cues
Top-down
- Knowledge and meaning
- Especially when the speech input is ambiguous, degraded, or noisy
Phoneme Restoration Effect
The brain restores the missing phoneme
- Silence -> missing/no restoration
- White noise -> clear speech/restoration
Visual Cues: McGurk Effect
Rely on visual articulatory information in speech perception
- When there is an ambiguous signal
Word Processing
- Mental Lexicon
- Semantic Network Theory
- Embodied Cognition
- Hubs-and-Spokes Model
Mental Lexicon
Stored representations of all the words a person knows, in their long-term memory
- Pronunciation, spelling, part of speech
- Meaning pointer (meanings are stored in a separate semantic network)
- TRACE model of auditory word
recognition
- Connectionist, interactive architecture
- Words and semantics are store in the different brain unit but at the end somehow cooperate
Semantic Network Theory
Concepts are represented in NODES, which are connected by LINKS (relationships)
- Meaning is based on physical features or similar things
Spreading activation
Activity at one node spreads to other nodes through links
- Automatic and fast
- Decreases in proportion to distance travelled
- Apple -> Pear = Faster
- Apple -> Red -> Roses = Slower
Criticism of Semantic Network Theory
Abstract view of meaning which embodied cognition approach suggest that meaning should use more of…
- Perceptual experience and
- Motor cortex or
- Interaction of the concept
- Not just abstract
- But with experience through 5 senses
Embodied Cognition
Words (symbols) and stored and learned through the perceptual experience of interacting with that concept
- E.g. APPLE
- Round-ish shape
- Usually red or green color
- A specific, sweet and fruity smell
- Sweet-sour taste
Hubs-and-Spokes Model
Storage and processing of word meanings in the brain
- Abstract + embodied representations
1) Abstract, amodal ‘hub’ (anterior temporal lobes)
2) Embodied semantics (distributed brain areas)
- E.g. Thunder sound activates other memory like what thunder sounds like
Sentence Processing
- Syntactic parsing
- Syntactic ambiguity
Syntactic Parsing
Constructing a syntactic structure from the words of the sentence, while you are hearing/reading
- Need to select a sentence interpretation
- Who did what to whom? (Where, when, how, why?)
Types of Syntactic Ambiguity
- Global
- Temporary
Global Syntactic Ambiguity
Overall meaning of sentence is ambiguous, even after reading the entire sentence
- Reason: at least 2 possible syntactic structures in your mind
- E.g. “The professor said on Monday he would give an exam.”
Temporary Syntactic Ambiguity
Sentence is initially ambiguous, but at the end there’s only 1 grammatical meaning
- Garden-path sentences
Garden-path Sentences
Temporarily ambiguous sentences that bias you towards a certain interpretation, which turns out to be wrong
- E.g. “The horse raced past the barn fell”
Costs of Syntactic Ambiguity
- Offline Processing: Subtle syntax
- E.g. “The horse raced past the barn fell” - Online Processing: Visible syntax
- E.g. “While Mary dressed, the baby played in the crib”
Ambiguous region: “While Mary dressed the baby played in the crib.”
- “baby” = Object of current phrase
- “baby” = Subject of new phrase
Disambiguating region: “While Mary dressed the baby played in the crib.”
- A verb, which needs a Subject!
- Need to fix the phrase structure
Principles of Online Sentence Processing
- Immediacy principle & incremental processing strategy
- Cognitive system needs to fix the initially-wrong interpretation
Immediacy Principle & Incremental Processing Strategy
- Interpret as much as possible, as soon as possible
- Use partial information to select 1 interpretation
- Don’t wait until you have all info from entire sentence
Cognitive system needs to fix the initially-wrong interpretation
- Initial interpretation: “baby” as Object of the verb “dressing”
- No place to attach the verb “play” !
- New interpretation: Move “baby” to be the Subject of the verb “play”
Discourse Processing
Construction-Integration Theory
Construction-Integration Theory
3 types of mental representations in processing cycles in working memory
1) Surface form
2) Text base
3) Situation model
- Create propositions
- Activate knowledge from LTM
- Connect propositions together & to the preceding text
Surface Form
Syntactic parsing
- Verbatim
- Precise, but short-lived
Text Base
Create propositions
- Abstract representation of event (with truth value)
- Predicate [agent, recipient, theme]
- Propositional approach to mental imagery
Situation Model
Building connections + Inferencing + Seeking coherence
- Meaning of overall discourse
Higher Number of Propositions
Lower amount and accuracy of recall
Inferencing
Essential to comprehension
- Use world knowledge to add information to situation model
- Information that was NOT directly stated in text
- E.g., missing link between 2
propositions
Common Types of Inferences
- Causal
- Bridging
- Instrument
- Elaborative
- Goal
Causal Inferences
The delicate vase fell from the shelf.
Inference: It broke.
Bridging Inferences
Timmy was riding his bike. He came home covered with bruises.
Inference: Timmy fell off his bike.
Instrument Inferences
The woman stirred her coffee.
Inference: She used a spoon.
Elaborative Inferences
Dan ate 20 plates of sushi.
Inference: Dan likes sushi.
Goal Inferences
Jan left early for the birthday party. She stopped at the mall on the way.
Inference: Jan wanted to buy a birthday gift.
Seeking Coherence
Incoherence makes texts difficult to comprehend
- More reading time
