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3019PSY > M4, T2, Types of dyslexia and explaining dyslexia via word recog models > Flashcards

M4, T2, Types of dyslexia and explaining dyslexia via word recog models Flashcards

1
Q

Dyslexia

A

Dyslexia – reading deficit/problems
Acquired Dyslexia – reading problems and deficits due to brain injury or damage
Developmental Dyslexia – failing to meet age relevant reading standards with normal intellectual functioning and educational opportunities for reading

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2
Q

Earliest cases of dyslexia

A
  • Dejerine (1891) patient with dyslexia and dysgraphia, (i.e., deficit in reading and spelling/writing respectively) due to infarction in left parietal lobe
  • Dejerine (1892) patient demonstrated a dissociation between reading and writing
  • Patient could write well but could not read printed words aloud or for comprehension
  • He could therefore not read things he had written
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3
Q

Types of dyslexia

A

Peripheral dyslexias: affect early stages in word recognition
visual analysis of letters or words

Central dyslexias : affect deeper processes
- grapheme-phoneme conversion
- orthographic input lexicon
- semantic access

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4
Q

Types of peripheral dyslexia

A
  • neglect dyslexia
  • pure alexia
  • letter position dyslexia
  • attentional dyslexia
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5
Q

Neglect dyslexia, Brain (1941)

A
  • Right hemisphere damage (parietal lobe) -> unilateral neglect
  • Patient does not attend to left side of space

Neglect Dyslexia – described by Brain (1941)
- Neglect dyslexia patient does not read left/right half page or word (Haywood & Coltheart, 2000)
- Not a consequence of unilateral neglect, can co-occur with unilateral neglect
- Errors for reading printed words – failure to identify part of/portion of word, page of text

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6
Q

Neglect dyslexia - examples

A

Neglect Dyslexia Left side
liquid -> squid
cage -> rage
yellow -> pillow

Neglect Dyslexia Right Side
book -> boot
milk -> mill
pen -> pet

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7
Q

Neglect dyslexia - defining symptoms (errors)

A
  • Errors are spatially determined visual errors consistently in left/right side of a word -> a neglect point in visual word reading
  • All letters correct on preserved side
  • Letters incorrect on the neglected side
  • Errors – very similar to original word in length
  • reading deficit occurs due to difficulty in specification of the word at the level of visual orthographic analysis
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8
Q

Pure alexia

A
  • Letter-by-Letter Reading or Alexia without Agraphia
  • Writing and spelling unaffected
  • Reading printed words is problematic
  • Brain damage/lesion typically located inferior portions of occipital lobe bordering on temporal lobe in left hemisphere also damage to posterior portion of corpus callosum
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9
Q

How pure alexia presents

A
  • Can identify letters
  • Reads words aloud - say one letter at a time – defining symptom
    CHAIR -> C…H…A…I…R -> “chair”
  • Patient names (or misname) some or all of the letters before a response is made
  • If patient can name all letters, then will correctly say word
  • Response times increase as word length increases (e.g., 10 seconds per letter within a word)
  • Occasionally patient can name short words without spelling e.g. ball
  • Role of letter confusability in pure alexia reading ability
    X, J vs C, G, Q
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10
Q

Pure alexia and the word recog model

A
  • Brain damage results in problem with early visual processing letter features
  • Impaired visual orthographic analysis
  • Word information going to reading system is noisy
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11
Q

Letter position dyslexia

A
  • Primary error – letter transposition e.g., broad -> board
  • Migration or transposition letters tend to be within word not initial or final letters
  • Patient data Hebrew readers – lot of possible transposition words compared to English
  • Correct letter identification but position coding of letters problematic
    jugde vs. judge
  • deficit at visual orthographic analysis
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12
Q

Attentional dyslexia

A
  • Person can read a single letter or a single word in isolation but cannot read the same word or letter if it is shown with items of the same type
  • Between-word letter migration errors – letter in one words appears within the other word
    -> Presented with WIN FED says FIN FED
    -> BFXQL asked to identify centre letter, says F or Q not X
  • Problem with narrowing attention
  • Deficit letter to word binding
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13
Q

Attentional dyslexia - brain stuff and particular region of word recog model

A
  • Exact location of brain lesion unknown but patients typically have damage to posterior left-hemisphere including subcortical structures
  • Difficulty with the visual specification of the word at the visual orthographic analysis level
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14
Q

Types of central dyslexia

A
  • surface dyslexia
  • phonological dyslexia
  • direct-route dyslexia (lexical non-semantic reading)
  • deep dyslexia
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15
Q

Surface dyslexia

A
  • Regular words read better than irregular words
    -> MINT FEAR VS PINT BEAR
  • Preserved regular word and nonword reading
  • Many patients worse at reading nonwords than matched real words
  • Errors
    -> Regularisations (yacht, sew)
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16
Q

Surface dyslexia - impaired pathways

A
  • intact grapheme-phoneme conversion rules
  • impairment of lexical route to reading aloud
    -> Orthographic Input Lexicon
    -> Orthographic Input Lexicon to Semantic System
    -> Orthographic Input Lexicon output to the Phonological Output Lexicon
17
Q

Phonological dyslexia

A
  • Poor or flawed nonword reading
  • Problems reading new words
  • Nonwords might be read as visually similar words
    SOOF -> soot
  • OK for well known (familiar) words
  • Impaired sub-lexical (non-lexical) route to reading aloud
18
Q

Phonological dyslexia - impairment pathways

A

Impaired sub-lexical (non-lexical) route to reading aloud
-> impaired grapheme-phoneme conversion module
-> impaired access to the grapheme-phoneme conversion module
-> impaired output from the grapheme-phoneme conversion module to the phonological output buffer

19
Q

Phonological dyslexia - impaired grapheme-phoneme conversion module

A
  • Non-word reading is non-existent
  • Learning to read new words is non-existent via sounding out
20
Q

Phonological dyslexia - impaired (slowed) output from the grapheme-phoneme conversion module to the phonological output buffer

A

Some phonological dyslexics better at reading nonwords when these are pseudo-homophones (nonwords that sound like real words e.g. brane) than when they are non-words unlike a real word (e.g. frane)

21
Q

Phonological dyslexia - impaired input into grapheme-phoneme conversion

A
  • Some non-words have one-to-one mapping between letters and sounds (graphemes and phonemes) e.g. trov
  • Some non-words have a letter that must be combined to form a sounds (phoneme) e.g., thoo, which is graphemic parsing
  • If there is a problem (noise) in the letter information coming into the Grapheme-Phoneme Conversion module phonological dyslexics will have more problems with non-words that need graphemic parsing
22
Q

Direct-route dyslexia

A
  • also known as lexical-nonsemantic reading
  • patient does not know the meaning of the word
  • patient can still read printed irregular words aloud
23
Q

Deep dyslexia

A
  • First systematic study – Marshall & Newcombe (1966)
  • Typically an acquired reading impairment
  • Cases of developmental Deep Dyslexia in the literature
  • Defining symptom semantic error in reading aloud
  • Symptoms of Deep Dyslexia typically unvarying across cases
24
Q

Deep dyslexia - symptoms when reading aloud

A
  • Semantic errors
  • Visual errors
  • Visual-then-semantic errors
  • Morphological errors
  • Very poor non-word reading
  • Imageability effect in reading words
  • Content word reading better than function word reading
  • Function word substitutions
25
Q

Deep dyslexia - semantic errors

A

Key symptom
Tandem -> cycle
Cost -> money
Decay -> rubbish

26
Q

Deep dyslexia - visual errors

A

Visual errors
Signal -> single
Decree -> degree

Visual-then-semantic errors
Sympathy (symphony) -> orchestra
Favour (flavour) -> taste
Charter (chart) -> map

27
Q

Deep dyslexia - morphological errors and poor nonword reading

A

Morphological errors (derivational errors)
Edition -> editor
Courage -> courageous

Very poor nonword reading (nonsense words)
Wux -> don’t know
Nol -> no idea

28
Q

Deep dyslexia - imageability effect

A

Better at reading concrete than abstract words

  • Better at saying ‘butter’ and ‘windmill’ than ‘grief’ and ‘wish’
  • Errors abstract words -> visually related imageable words
29
Q

Deep dyslexia - content v function words

A

Content words (nouns, verbs, adjectives)
Function words (was, quite, of)

Function word errors
Was -> with
If -> yet
Quite -> perhaps
Yes -> small words are the worst

30
Q

Deep dyslexia - spelling and writing

A
  • Spelling and writing may be impossible
  • If spelling and writing possible then symptoms are equivalent to those listed for reading printed words aloud
  • Majority of patients with deep dyslexia show all of these symptoms
31
Q

Explanations for deep dyslexia

A

Impairment(s) to the normal left hemisphere reading system through many different locations of damage
OR
Reading occurs via a secondary right hemisphere reading system

32
Q

Deep dyslexia and the left hemisphere reading model part 1

A
  • Damage Grapheme-phoneme conversion– inability to read non-words
  • Damage Semantic System - semantic errors, and imageability effect
  • Damage Orthographic Input Lexicon- visual errors
  • Impaired connection between orthographic input lexicon and phonological output lexicon – poor word reading and function word errors
33
Q

Deep dyslexia and the left hemisphere reading model part 2

A
  • Damage to connection between semantic system and phonological output lexicon – patient correctly understands a printed word but makes a semantic error reading it
  • Damage to component syntactic system processes prefixes and suffixes (morphological errors)
34
Q

Deep dyslexia and right hemisphere hypothesis

A
  • If the left hemisphere cannot complete (orthography, semantics or phonology) then the right hemisphere reading system must take over
    -> Coltheart (1980, 2000) Deep Dyslexia is a loss access in the Orthographic Input Lexicon in the left hemisphere (cannot read printed words)
    Deep Dyslexic reads “words”
  • via Orthographic Input Lexicon in the Right Hemisphere
  • Activates semantic system representation in the Right Hemisphere
  • Information from Right Hemisphere semantic system sent to the Phonological Output Lexicon in the Left Hemisphere (needed to say word aloud)
    *look up image
35
Q

Explaining deep dyslexia errors via the right hemisphere reading

A
  • Grapheme-Phoneme conversion non-existent in right hemisphere - nonword reading errors
  • Imageability effect - visual field studies show better performance for concrete than abstract words in right hemisphere
  • Semantic errors made in patients with no left hemisphere
  • Semantic errors may also result from incorrect target selection being transferred to left hemisphere or incomplete semantic word representation to start with
  • Function words are poorly represented within the right hemisphere
36
Q

Deep dyslexia and right hem reading, syntactic processing and visual errors

A

Syntactic processing in right hemisphere not as good as left hemisphere - morphological errors

May also explain the visual errors – poorer word representation in right hemisphere and therefore visually close word is selected as target words

37
Q

Deep dyslexia relevant brain regions (Coltheart, 2000)

A
  • Coltheart (2000) imaging study relevant areas include:
  • Orthographic processing – left occipital and occipitotemporal regions
  • Semantic processing – border between superior and middle temporal gyrus, areas BA21 and BA22 (Left Hemisphere)
  • Phonological output – left hemisphere frontal operculum
    *look up images (3)

3019PSY (23 decks)

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