Disorders%20of%20Lexical%20Selection%20Garret%201992b - PowerPoint PPT Presentation
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Disorders%20of%20Lexical%20Selection%20Garret%201992b
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Field Effects stable across time. Rare or common words had no affect on Field effects ... Case study of Wernicke's aphasia patient with no difference between high ... – PowerPoint PPT presentation
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Title: Disorders%20of%20Lexical%20Selection%20Garret%201992b
1
Disorders of Lexical SelectionGarret 1992b
- Brian Nisonger
2
4 types of Linguistic errors
- Message to Lemma Representation
- Lemma to Word Form Representation
- Word Forms to phonetic representation for
connected speech - Speech representation to motor representation
- This paper deals with the first two
3
Lexical Disorders
- Aphasias
- Loss of usage or comprehension of words
- Brocas Aphasia
- Characterized by the inability to produce
complete grammatical sentences - May be missing function words, pronouns or other
categories - Comprehension may or may not be impaired
- Wernickes Aphasia
- Can produce fluent sentences
- Usually semantically nonsensical
- Comprehension is impaired
4
Lexical Disorders-II
- Dyslexias
- A reading based learning disability that impairs
the ability to read - Deep Dyslexia
- A reading disorder where semantic errors occur
- BushgtTree
- AntiquegtVase
- UnclegtNephew
- Alzheimer's disease
5
Semantic Deficits of Lexical Selection
- Normal Errors vs Lexical Disorders
- Similarities
- Word Substitution Errors
- Synonymic
- Antonymic
- Associative
- TOT states
- Differences
- Grammatical Categories
- Hypernyms
6
Hypernym Problems
- Object Oriented Programming
- Inheritance
- AnimalgtHorse
- PlantgtFlower
- Supertype
- Generally if W1 entails W2 then W2 is a hypernym
of W1 - Substitution rare in normal speech errors, common
in lexical disorders
7
Categorical Organization
- Alzheimers Patients
- Visual Naming Task
- Hypernym substitution
- General substituted for Specific
- Errors may be related to normal speech when a
word is unavaliable - I bought a plant
- I bought a flower
8
So what does it mean so far?
- Lexical Representations in the brain
- MessagegtLemma
- LemmagtWord Form
- Word FormgtPhonetic/Orthographic representation
- Specifically divided Phonetic from Orthographic
- Deep Dyslexia only orthographic
- Other aphasias can be both phonetic and
orthographic - Concepts Space
- Hierarchical in nature
- Semantic Fields
- Garret 1992a
9
Lexical Retrieval System
- Parallel Featural Tests
- Linked Decision Tables
- Table internal test parallel
- Table -gt Table serial
- Might account for loss within categories
- But ability to categorize within fields
10
Semantic Field Effects
- Selective Impairments
- Loss of ability to generate words from specific
domains - Major
- Concrete/Abstract
- Living/non-living
- Animate/Non Animate
- Interesting cross phenomena with Worlds
Languages? - Minor
- Color Items
- Food Items
- Numbers
- Baseball Players
- Still possible to recognize words are of a
certain category for some aphasia and other
disorders but not produce them
11
More Field Effects
- Affected categories
- As low as 10 generation
- Non-affected categories
- Near normal performance
- Field Effects stable across time
- Rare or common words had no affect on Field
effects - For example
- Animal-gtBear
- Fruit-gtPrickly Pear
12
How does it fit in with the model?
- Semantic Fields are a set of Lemmas
- Grouped by specified functional similarity of
concepts - Possibly used for rapid evaluation of
alternatives in production - Lexical Ambiguities
- In normal errors we see this affect as well
- Garret 1992a
- Aphasic Loss
- Major vs Minor categories
13
Some Distinctions and Cross Classification
- Examples
- Possible to have losses in Concrete Inanimate
category - No loss in Concrete Animate category
- Living vs NonLiving
- Seems to have less cross classifications
- Sensory description
- May not be relevant for inanimate non-concrete
- Functional
- Not relevant for living things but very relevant
for inanimate - May be explained by other factors, but interesting
14
Higher Level Feature Errors
- Wheel-gtFoot
- Analogical relation between target and intrusion
- Function
- Mode of motion
- Limbs
- Foot
- Mode of motion
- Drive Train system
- Wheel
15
Where are we at
- Clear field effects in aphasic errors
- Similar to effects noted in normal speech
- Evidence for difference between
- concept representationgtlemma representation
- concept representationgtperceptional represention
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Causes of Semantic Error
- Need to categorize errors
- Components of lexical system
- Production
- Comprehension
- Most accounts dont separate
- Concept
- Lemma
- Two major categories of errors
- Conceptual impairment
- Lemma processing
- ConceptgtLemma
- Lemma Replacement Failure
- LemmagtWord Form
- Word Form Output System Error (Possible 4th
category)
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Possible Reasons for Multiple Semantic Activation
- Semantic Spreading
- Multiple words are activated
- MessagegtLemma
- Message fragments can activate multiple lemmas
which then are filtered through by more completed
message fragments
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Failure of the Output System
- Generation
- Failure to filter alternative lexical candidates
- Failure to produce lexical candidates
- Possible correlation to normal speech errors
- No real evidence besides intuition
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Auditory vs Orthographic
- Loss of category can be specific to either
auditory or orthographic forms - Loss of abstract for example may be present in
auditory experiments but absent in orthographic
experiments
20
Modality-Specific Failures
- Modality
- Verbal
- Non-verbal systems
- Semantics may be independent of the verbal system
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Semantic Modality
- Tactile naming experiments
- Ability to mime usage of object
- Inability to name the object
- No knowledge of name
- Not TOT
- May cross classify with semantic field effects
- Loss of specific categories in non-verbal naming
tasks such as tactile naming
22
What is semantics?
- Possible that semantics may not be just limited
to lexical meaning - Usage
- Visual recognition
- Relative Size
- Relative Location
- Visual problem solving intersections
23
Syntactic Category Effects
- Open Class
- Nouns, verbs, adjective, adverbs
- Closed Class
- Determiners, Prepositions, modals, negation,
predicate markers
24
Closed Class Retrieval Failures
- Comprehension
- May or may not have inability to comprehend
grammatical function words - Production
- Telegraphic
- Doctor office Monday teeth
- No link between inability to produce grammatical
words and comprehension of grammatical words
25
Types of closed class failures
- Agrammatical
- Inability to produce grammatical categories
- Paragrammatical
- Producing the wrong grammatical categories
- Usually comprehension problems
- Overlap
- In Hebrew grammatical category cannot be omitted
- Brocas aphasia patients often pick incorrect
endings - Brocas aphasia Agrammatical
26
Closed Classes Failures of Deep Dyslexia
- Fewest errors with concrete nouns
- Highest errors for closed classes
- Inability to read closed class words in isolation
- Longer passages may provide context for guessing
- Possible failure of lemmagtword processing
27
Alternate Retrieval System for Closed Classes
- Failures in open class not found in closed class
- Phonemic paraphasias
- Substitutions of non-correct sounds
- Neologisms
- Non-words being introduced as words
- Possibility that grammatical structure selects
for specific words within specific domains within
the closed classes instead of as a whole - Activation of multiple meanings may be different
in closed classes and open classes
28
Major Category Contrasts
- Normal speech substitutions do not cross
grammatical categories - Nouns substitute for Nouns, etc.
- Wernickes Aphasias patients
- Substitutions do not cross grammatical category
29
Nouns and Verbs
- Categories can be lost in modality specific tasks
- Ex Two patients showed loss of verbs in oral
output, but not in written - Agrammatics
- More Loss of verbs in tasks across all modalities
- Anomics
- Disorder associated with dysfunction in word
finding - No other disorder-frequent circumlocution
- More loss of nouns across all modalities
30
Nouns and Verbs-IIWhat does it mean?
- Anomics the failure may be at the word-form
retrieval level - Agrammatics the failure may be at the phrasal
construction or lemma level
31
Frequency and Grammatical Category Effects
- Be/Bee wood/would
- Show opposite effects for Brocas vs. Wernickes
aphasia regardless of frequency - Case study of Wernickes aphasia patient with no
difference between high frequency and low
frequency words - Possibly only affects open class words and not
closed class words
32
Summary
- The effects of aphasia illustrate some of the
mechanisms of the lexical retrieval system - Specifically
- ConceptgtLemmagtPhonological/Orthographic form
- By studying aphasias we can understand how
lexical retrieval works and what that means for
lexical ambiguity
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