Disorders of Reading Flashcards
What is alexia with agraphia?
Impaired reading along with impaired spelling or writing
What is alexia without agraphia?
- Impaired reading but intact spelling or writing
- Paradoxial inability to read words that they had just written
Dejerine first coined the agraphia terms, what did he argue?
1) In the angular gyrus, there is a center for the visual images of letters that is necessary for both reading and writing
2) Damage to the center itself = would lead to alexia with agraphia
3) Dissconnection of the center from visual areas = alexia without agraphia
How did Marshall & Newcombe come to propose a two-route model of reading?
The model was based on the error patterns..
- Surface dyslexia
- Deep dyslexia
What is deep dyslexia associated with?
An impairment in the sound analysis system
What is surface dyslexia associated with?
An impairment in the meaning analysis system
What are the 3 potential routes for reading?
1) Visual Analysis System -> Visual Input Lexicon -> Semantic system -> Speech Output lexicon -> Phoneme level -> Speech
2) Visual analysis system -> Visual Input Lexicon -> Speech Output Lexicon -> Phoneme Level -> Speech
3) Visual analysis system -> Grapheme Phoneme Conversion -> Phoneme Level -> Speech
Describe Peripheral Dyslexias
Occur early on in the visual analysis process for reading
Describe Central Dyslexias
Disorders that happen once thye get past the analysis system
What are the 3 types of dyslexias?
1) Neglect Dyslexia
2) Attentional Dyslexia
3) Letter By Letter Reading
Define Neglect Dyslexia
Neglect half of the world
Ex. cowboy = boy
Ex. milk = chalk
Define attentional dyslexia
Can see the whole world but can’t identify individual letters
Define Letter-by-letter reading
Pure alexia completely abolished, you read letters better than words
- Very labored sequential process
- Shown the word book: “B-O-O-K… Book”
- Long words should take more time to read than short ones
- Script more difficult than print
- Can not read with breif presentations
- Impairment occurs after letter-form processing
What route is impaired in letter-by-letter peripheral dyslexia?
There is an imapirment in their visual analysis system which leads to the subsequent pathway not being utilized
- Patients develop a compensatory procedure to circumvent the visual analysis system impairment
Describe surface level dyslexia
Damage to sound analysis
1) Assigning inapproporatye sounds to ambiguous grapheme OR assigning phonetic value to silent grapheme
Ex. insect»_space; insist
Ex. listen»_space; liston
2) Regularization: Applying valid correspondence rules
Ex. disease»_space; decease
Ex. gone»_space; goan
3) Influenced by Regular vs. Irregular Word Manipulation
What route is impaired in surface dyslexia?
- What do surface dyslexia errors reflect?
Impairment in the
Visual Analysis System -> Visual Input Lexicon -> Speech
Errors reflect attempts to read soley through graphene-phoneme correspondence rules
What route is impaired in deep dyslexia?
the visual analysis system to visual input lexicon
Describe the behaviour of deep dyslexia patients
Specific errors?
They do not extract phonetic information from words, instead they read as if words are an ideogram
Semantic Error
- ill»_space; sick
- cheer»_space; laugh
Visual
- life»_space; wife
- sword»_space; words
visual then semantic
- sympathy»_space; orchestra
- favor»_space; taste
there is a lack of a phonological check
What is the right hemisphere hypothesis of deep dyslexia?
Patients aren’t reading though the left hemisphere AT ALL
- It’s not the selective damage of a single pathway, but BOTH pathways in one hemisphere
- Deep dyslexics have a damage LH system and are reading though the right hemisphere
- Word recognition is mediated by the visual input lexicon in the right hemisphere
- The RH doesn’t have the infrastructure to read phonologically leading to an over-reliance on semantic representations
What can the RH do?
- Analyze orthographic (visual/written text) input
- Orthographic analysis leads to the semanticization NOT phonological interpretation
- Cannot produce speech
What can the LH do?
- All functions
- Note that the speech production system is seperate and beleived to be in tact in deep dyslexia
Whats happending in deep dyslexia in terms of hemispheres?
- Patients can produce speech but cannot gain access from print to the orthographic lexicon in the LH
- Thius the orthographic input enters the RH, semantic info sent over to the LH, and then there is phonological output
What is evidence for lateralization in split brain patients?
When word stimuli shown to RH, cannot interpret rhyme or non-words
What is evidence for laterization in left hemispherectomy patients?
Make semantic errors akin to DD
Describe phonological dyslexia
In phonological dyslexia, patients have impaired non-word reading but intact lexical reading
They will “regularize” non-words: e.g. they will say the word “soot” when presented with “soof”
They respond with a real word because they can only read throguh their lexicon and can’t sound out the words phonologically
But wait! the marcel model might be flawed. what indicates that thier model is flawed?
Are there really two routes that bypass the semantic system?
Is there really a ‘pure’ GPC route seperate from the lexicon? why?
What do the errors made by surface level dyselxia patients indicate?
Errors have a hint of lexical involvement
- Ex. Show a patient “incense” and they say “increase” - increase is the more common word AND phonological pronounciation of incense
- Performance is also graded in a way that suggests word meaning/frequency knowledge
- In children: they try and mathc a new word to an old word that they know previously
- Sounding words out is a last resort
