L6 - neural basis of reading Flashcards
three types of peripheral dyslexia
- pure alexia
- attentional
- neglect
pure alexia:
- type
- lesion
- symptoms
- implications
type: peripheral
lesion: occipito-temporal
symptoms: reading times proportionate to word length: impaired letter identity representation (no impairment of spelling, writing or verbal language)
Implications: impaired visual word form procesisng
attentional dyslexia:
- type
- lesion
- symptoms
- implications
type: peripheral
lesion: parietal
symptoms: inability to focus while suppressing flanking stimuli and letter migration error (e.g. WIN FED > FIN FED)
Implications: impaired attention to visual processing
Neglect:
- type
- lesion
- symptoms
- implications
type: peripheral
lesion: parietal
symptoms: neglects one side of word (e.g. reads clock as block)
implications: impaired attention in visual processing
types of central dyslexia:
- surface
- phonological
- deep
surface dyslexia:
- type
- lesion
- symptoms
- implications
type: central
lesion: superior temporal
symptoms: cant read irregular words (e.g. pint reads as p-i-nt)
implications: impaired phonological lexicon
phonological dyslexia:
- type
- lesion
- symptoms
- implications
type: central
lesion: temporo-parietal
symptoms: cant read non-words (e.g. reads CHURSE as NURSE)
implications: impaired grapheme-to-phoneme conversion
deep dyslexia:
- type
- lesion
- symptoms
- implications
type: central
lesion: temporal (Extensive)
symptoms: semantic errors (CAT > DOG), derivational errors (BEG > BEGGAR), read concrete words better than abstract words
implications: impaired semantic memory
the writing system:
- alphabetic versus logographic
- i.e. English versus Japanese
- transparent versus opaque orthography
- i.e. opaque = leicester
grapheme
the smallest meaningful unit of written language (analogous to the term ‘phoneme’ in spoken language)
word length?
actual visual process of recognising words is not strongly affected by word length
visual word recognition?
appears to be greater then the sum of its parts
word superiority effect
it is easier to detect the presence of a single letter presented briefly if the letter is presented in the context of a word.
- suggests that there are units of representations corresponding to letter clusters
lexical decision task
participants must make a two-way forced-choice judgement - whether a letter string is a word or not.
Pseudo-words are much faster to reject if they don’t resemble real words e.g. BRINJ versus BRINGE.
how are lexical decision tasks carried out:
- performed by matching perceived letter string with a store of all known letter strings that make up words
this is termed the VISUAL LEXICON
