Transcript Language - Victoria University of Wellington

Language
Ref: Banich pp. 286-298
Classical Model of Language
BUT:
1.
Predicted Patterns Never "Absolute“
2.
Symptoms can dissociate
Multi-component view
All of these can become selectively impaired:
Anterior (around Broca’s area):
• Articulation of speech
• Understanding syntactic relationships
Posterior (around Wernicke’s area):
• Retrieval of phonemes for production
• Selection of words for production
• Access to semantic info about words
Examples of Components
Articulatory Planning:
• Anterior (overlaps Broca’s area)
• Damage: halting, effortful, distorted
speech
Retrieval of Phonemes:
• Posterior (nr. Wernicke’s area)
• Damage: good articulation, but can’t recall
word sounds, make phonemic paraphasias
e.g. Turtle: um.. tornet, no that's not right....
(etc)... turking.. that's wrong what's the end
part?…
Examples of Components
Access to Semantic Info.
• Posterior (overlaps Wernicke’s area)
• Damage: P can’t understand word
meanings, produces semantic
paraphasias:
e.g. Turtle: That’s some kind of animal,
isn’t it. A seal, is it?
Anterior vs. posterior areas
Posterior language regions (LH) are involved in:
Storage/retrieval of familiar, well-learned relationships
e.g. phoneme sequences of common words
meanings of common words
Anterior regions are involved in:
Generation of new combinations
e.g. sentences (novel combinations of words)
articulation (must be done afresh each time)
Reading
Ref: Banich: Visual language,
pp. 295-299 (up to writing)
Coltheart’s Two Route Model
Lexical (or direct)
route
Print
Lexicon:
word sounds
and meanings
Grapheme-phoneme
(or phonological)
route
Grapheme-phoneme
Conversion
e.g. sh -> /s/
Pronunciation
Coltheart’s Two Route Model
Lexical route:
• Recognise whole word
• Look up in lexicon
• Good for known words (not unfamiliar words)
Grapheme-phoneme route:
• Identify graphemes (e.g. b, k th, sh)
• Convert each grapheme to a phoneme
• Good for regular words (e.g. cat) but not irregular
words (e.g. yacht)
Dyslexia
Acquired Dyslexia = reading impairment resulting from damage
to brain
(cf. Developmental dyslexia = reading impairment present
throughout development)
Two major types of acquired dyslexia:
Phonological dyslexia = Damage to grapheme-phoneme
route
Surface dyslexia = Damage to lexical route
Phonological dyslexia
Grapheme-phoneme route damaged:
Print
• can’t read nonwords, unfamiliar
words
Lexicon
Graphemephoneme
conversion
• lexicalisation errors
e.g. heef -> beef
• OK on familiar words: prob. may
go undetected
Pronunciation
• regularity not important
(yacht = yet)
Phonological dyslexia
Tests: PALPA (Psycholinguistic Assessment of
Language Processing in Aphasia)
-> Nonword reading subtest
ked
bem
nar
cug
fon
lat
shid
boak
doop
birl
dusp
soaf
Phonological dyslexia
Localisation:
Surface dyslexia
Lexical route damaged:
Print
Lexicon
- can’t read irregular words
e.g. yacht, pint.
Graphemephoneme
conversion
Pronunciation
- regularization errors
e.g. pint -> /pInt/, busy -> buzzy
One patient, when given the word
"listen" to read, pronounced it
"Liston", then exclaimed "Liston,
the boxer!“
- OK on regular words, even
unfamiliar ones
Surface dyslexia
Tests: PALPA spelling-sound regularity subtest
effort (R)
pretty (E)
middle (R)
barge (R)
break (E)
envy (R)
blood (E)
bowl (E)
plank (R)
navy (R)
ceiling (E)
iron (E)
cough (E)
context (R)
rub (R)
routine (E)
bury (E)
yacht (E)
flannel (R)
tail (R)
wolf (E)
island (E)
wedding (R) chicken (R)
colonel (E)
luck (R)
smog (R)
nerve (R)
Surface dyslexia
Localisation:
Double Dissociation
Irregular
words
Unfamiliar
words
Phonological dyslexics
Good
Poor
Surface dyslexics
Poor
Good
Other types of dyslexia
• Surface and Phonological are examples of Central
dyslexias (a third subtype to come)
• Peripheral dyslexias: visual analysis of word
e.g. letter-by-letter reading: can't perceive whole word
Deep Dyslexia
• Another kind of “central dyslexia”
• Can't read unfamiliar words (like in phonological
dyslexia)
• BUT also have problems with known words
(esp. function words, abstract words)
•
Complex errors:
semantic e.g. affection -> love
visual
e.g. science -> scene
Deep Dyslexia
Reading by Patient BM
sour:
bad
thirst:
thirsty
lamp:
lap
clothing:
clothes
insult:
imbecile? no...
decent:
I know what it is, but I can't say it
capacity:
absence
applause: its clapping
Deep Dyslexia
•
Both "routes" seem affected:
- can't use grapheme-phoneme route
- also unable to reliably access lexicon directly
• Sometimes partial access:
Patient AR:
Ostrich: "I get the impression of an animal“
Localisation: Extensive damage to LH
Explanations for Deep Dyslexia
1. Imperfect Lexicon:
• P can't use grapheme-phoneme route at all
• therefore, must rely on what's left of lexical route
• errors occur when word not available in lexicon
• evidence : similar errors in other language tasks
Explanations for Deep Dyslexia
2. “Right Hemisphere Reading":
• LH so damaged, P
relies entirely on RH
• RH word knowledge
limited
• Evidence : increased
RH activity in
dyslexics (fMRI)
Anterior
production
areas
LH lexicon
(damaged)
CAT CAT
RH lexicon
(intact but
limited)