PALPA - Columbia University

Report
Models of Language
Language and Cognition
Colombo 2011
Principals of Cognitive Models
• A means of conceptualising the stages involved in
a mental activity
• Examines components involved in processing
information and the interconnections between
them (“box and arrow”) or how information
flows between centres via pathways
• The boxes and arrows represent a function which
can be independently impaired
• Not yet able to link aphasic symptoms to discrete
anatomical structures
Principals of Cognitive Models
• Provide a framework for assessment and
treatment
• Different models consider different aspects e.g.
single words (Ellis and Young 1988) and sentence
processing (Garrett 1984).
• Different models share common features, e.g. all
have distinct semantic and phonological levels
• We will be focusing on one lexical model widely
applied in SLT
Assumptions
• Using this modelling make several assumptions:
– Functional modularity – modules/boxes can operate
independently of other components
– Anatomical modularity – modules represent different
parts of the brain. Lesions can affect selected
modules only, leaving others unimpaired
– Universality – all people have the same fundamental
language system (though we might not agree on the
system)
– Subtractivity - brain damage can only remove
elements from the system, not add them
• N.B:
• Lesions in the brain vary from person to person
dependent on:
– The precise location of the damage
– Which white matter fibre tracts are damaged
• Therefore identical patterns of deficit in any two
people unlikely.
• Helpful to look at which boxes/arrows are
damaged/intact to help explain pattern of
performance.
• Still attempting to relate to brain structures (Hillis
2001)
PALPA
Psycholinguistic Assessments of
Language Processing in Aphasia
Introduction
print
Mouse
mouse
Abstract Letter
Identification
“yes, these are letters”
m
o
e
Visual Input
Lexicon
Semantic
System
Phonological
Output Lexicon
speech
“yes, this is a word”
s
u
Mouse = N
“yes, this word means something”
“this word is pronounced /maUs/”
“mouse”
print
Blik
blik
Abstract Letter
Identification
“yes, these are letters”
b
l
i
Visual Input
Lexicon
c
k
“no, this is not a word”
Semantic
System
Phonological
Output Lexicon
speech
• This doesn’t fit with the
facts…
• So there must be another
way to read written words
print
Blik
blik
Abstract Letter
Identification
Visual Input
Lexicon
Semantic
System
Grapheme
to Phoneme
Conversion
b=/b/ , l=/l/, i=/I/, k=/k/
Phonological
Output Lexicon
“blik”
speech
• The lexical route cannot
read nonwords at all
• The nonlexical route cannot
read irregular spelling-sound
correspondences
• We need (at least) both of
these routes to be able to
read both real and pseudo
words
• What about naming an object or a picture?
pictures,
seen objects
print
Abstract Letter
Identification
Visual Object
Recognition System
Semantic
System
Phonological
Output Lexicon
speech
Visual Input
Lexicon
Grapheme
to Phoneme
Conversion
• What about recognizing or repeating speech
that you hear?
pictures,
seen objects
speech
Auditory Phonological
Analysis
“yes, I hear speech sounds”
Phonological Input
Lexicon
“yes, that’s a word”
print
Abstract Letter
Identification
Visual Object
Recognition System
Semantic
System
Phonological
Output Lexicon
speech
Visual Input
Lexicon
Grapheme
to Phoneme
Conversion
• What about being able to repeat a word you
never heard before – or a pseudoword?
pictures,
seen objects
speech
Auditory Phonological
Analysis
Phonological Input
Lexicon
print
Abstract Letter
Identification
Visual Object
Recognition System
Acoustic to
Phonological
Conversion
Semantic
System
Phonological
Output Lexicon
speech
Visual Input
Lexicon
Grapheme
to Phoneme
Conversion
• What about people who do not understand
what they hear, or what they read, but can still
say it?
pictures,
seen objects
speech
Auditory Phonological
Analysis
Phonological Input
Lexicon
print
Abstract Letter
Identification
Visual Object
Recognition System
Acoustic to
Phonological
Conversion
Semantic
System
Phonological
Output Lexicon
speech
Visual Input
Lexicon
Grapheme
to Phoneme
Conversion
• What about written output?
pictures,
seen objects
speech
Auditory Phonological
Analysis
Phonological Input
Lexicon
Abstract Letter
Identification
Visual Object
Recognition System
Acoustic to
Phonological
Conversion
Sound to
letter rules
print
Visual Input
Lexicon
Grapheme
to Phoneme
Conversion
Semantic
System
Phonological
Output Lexicon
speech
Orthographic
Output Lexicon
writing
The final product…..
• Kay, Lesser & Coltheart,
1996
• PALPA model
• Assessments for each box
and arrow – evaluating
effects of different inputs
and outputs on a damaged
language system
• NOT intended to be used in
its entirety
• Remains the only
psycholinguistically
motivated tool for language
assessment

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