lecture 4 - acquired dyslexia syndromes

Question 1

what are the two types of acquired dyslexias

Answer 1

1 - peripheral dyslexias

2 - central dyslexias

Question 2

what is periphereal dyslexia ?

Answer 2

Refers to any reading disorder in which seeing a word as a stable orthographic object fails.

Due to a failure at an earlier stage – I.e. before recognizing the linguistic relevance of the stimulus.

Question 3

what is central dyslexia ?

Answer 3

Refers to any reading disorder in which impairment occurs after the stage of visual word form.

Concern the reading system per se. They are therefore psycho/neurolinguistic in nature.

Question 4

main symptom of peripheral dyslexias?

Answer 4

Main symptom: Word identification impossible, except via explicit sequential identification of individual letters (slow and painful).

Question 5

what is the ‘Saffran effect’?

Answer 5

The ‘Saffran effect’ (Saffran & Coslett, 1998):

Pure alexics are well above chance in categorizing the meaning of a word (is it an animal?) or lexical status of a letter string (is it a real word?), despite their inability to “consciously” identify the word.

Question 6

what cerebral area is involved in peripheral dyslexias?

Answer 6

visual word form area (VWFA; ventral occipito-temporal region) damaged or disconnected.

Question 7

what are two types of peripheral dyslexias?

Answer 7

1. attentional dyslexia

2. neglect dyslexia

Question 8

Attentional dyslexia – shallice and warrington 1977

Answer 8

Very rare

Associated with left parietal lesion

Difficulty in identifying letters or words when flanked by other items of the same category

However, naming of a letter or a word in isolation preserved.

‘o’ on its own is fine, but errorprone in ‘word’;

‘word’ on its own is fine, but erroprone in ‘when the word is in a sentence’.

Question 9

Neglect dyslexia – ellis, flude, and young 1987

Answer 9

failure to identify the initial or final letter(s) of a word or group of words, resulting in omissions, substitutions or additions.

Question 10

types of central dyslexias

Answer 10

1. phonological dyslexia
2. deep dyslexia
3. semantic dyslexia
4. surface dyslexia

Question 11

phonological dyslexia -

Answer 11

Main symptoms – impaired ability to read new or made up word (or nonwords), and to sound out individual graphemes.

Lesion of the temporal lobe dominant

Question 12

deep dyslexia -

Answer 12

Associated with extensive damage to the dominant (L) hemisphere, and consists of:

Impaired ability to read nonwords.

Semantic errors: ill > ‘sick’, bush > ‘tree’, bad > ‘liar’

Visual errors: life >’wife’, sword >’words’

Derivational errors: card > ‘cards’, fleeing > ‘flee’, entertain > ‘entertainment’, beg > ‘beggar’

Effect of syntactical class:

nouns > adjectives > verbs > functors

Effect of imageability: concrete > abstract words

Question 13

semantic dyslexia -

Answer 13

reading without meaning

Disorder associated with neurological disease (e.g. Alzheimer, semantic dementia).

Main symptom: ability of patients to read fast and fluently (even irregular words in some patients), but inability to comprehend what they are reading.

‘I don’t know the word, I can only read’ (from McCarthy & Warrington, 1982).

Question 14

surface dyslexia -

Answer 14

Main symptoms:

Regularisations (typical pronunciation chosen), especially for low frequency irregular words, e.g., ‘pint’ rhyming with ‘mint’

Stress shift, e.g. guiTAR > ‘GUItar’

Comprehension based on pronunciation, e.g., bear as ‘alcoholic beverage’ (beer).

Failures to apply contextual rules, e.g. insect > ‘insist’, guest > ‘just’

Incomplete decoding of digram vowels, e.g. niece > ‘nice’