week 9 Flashcards
(21 cards)
Reading as a learned expert system
Not innate abilities, but rely on aspects of spoken language processing and other skills (visual, memory, etc) that may have genetic component
Studies of Eye Movements
Accurate control of eye movements (for foveal vision) needed
Studies of saccades and fixations show we don’t focus on every letter.
Influenced by many factors:
Reading direction (e.g. English take in more info from right of fixation)
Length of the word
Predictability
Diversity of writing systems
Logographic: one symbol = one word (e.g. kanji)
Syllabic: one symbol – syllable (e.g., kana)
Alphabetic
Different orientations
Why is brain imaging useful to study reading?
Neuroimaging uses:
See what happens in the brain as reading happens and how it differs from spoken language
Changes in brain structure (MRI) and function (fMRI) as reading develops
Associate neural correlates with models of reading.
The main regions activated by reading
Left inferior frontal gyrus
Left temporoparietal cortex
Left infero-temporal cortex
Serial vs. parallel processing (global recognition)
Visual word recognition not strongly affected by word length (parallel processing)
May involve processing letter clusters rather then individual letters
Cf. Word superiority effect
Evidence for top-down effects on visual processing
The visual word form area
An area in the fusiform (occipitotemporal) gyrus responds to
words more than false-fonts or consonant strings (chair vs. ckmn)
Upper and lower case equally: chair vs. CHAIR vs. cHaIr
Real words more than non-words sounding the same: taxi > taksi
Orthographic identity of the word
Characteristics of Visual Word Form Area
Not strictly visual: responds to Braille reading in congenitally blind
Depends on experience: left lateralisation depends on level of literacy
Depends on interactions with spoken language: in left handers it goes in the language-dominant hemisphere
The visual word form area (VWFA) remains controversial
FMRI study shows activation for object naming and reading words
Fusiform face area in RH, so VWFA might result of developing expertise in reading
Adapted from areas dedicated to object/ face recognition
Cf.‘Neuronal Recycling Hypothesis’
Reading brain – emergence and modulation with experience
When a child learns to read – increased reading-related activity in this region of occipitotemporal cortex
Not just the VWFA: Across childhood and early adulthood, increased phonological skill is associated with increased reading activity (Turkeltaub et al., 2003) and increased cortical surface (Merz et al., 2019) in left perisylvian areas
Reading network modulated by environmental factors, e.g. SES
Acquired disorders of reading and writing
Central disorders
Central dyslexia and dysgraphia: problems with wordforms or meanings
Damage to ventral or dorsal language routes
Peripheral disorders
Peripheral dyslexias: visual analysis problems
pure alexia (letter-by-letter reading)
neglect/attention dyslexia
Peripheral dysgraphia
Control of motor commends, etc
Peripheral dyslexia: pure alexia (letter-by-letter reading)
Acquired reading disorder (loss/laborious) without impairment of spelling, writing or verbal language
Can arise from damage to VWFA or disconnection to meaning
All aspects of language are fine
Slow (serial) reading varying with length
Difficult letter identification
Peripheral dyslexia: neglect dyslexia and dysgraphia
In reading:
Miss one side of the page
Out loud: miss the beginning of words
Delete a sound/letter: CAGE > AGE
Substitute a sound/letter: PEACH > BEACH, LOG > DOG
Incomplete information reaching the VWFA
In writing:
Write in one side of the page
Miss beginning letter
Central reading processes
Reading up to the VWFA – encoded visual word form
Reading from the VWFA onwards…
How do we access the word meaning?
How do we transform the visual word into a spoken word?
Ventral and dorsal routes in reading
Ventral route connecting to auditory processing and meaning
Mapping visual word to meaning
Dorsal route connecting to phonological processing areas (STG) and motor areas
Mapping visual word to sounds and motor plans
The phonological route – sounding out written words
Is a PHOKS an animal?
Can you sail in a YOTT?
Should we build our HOWZIZ from straw?
Without ever seeing PHOKS before, we can pronounce it
We can pronounce non-words: KAL, MATAL, PILU
Mapping letters to sounds
Grapheme-to-phoneme conversion
Disorders of reading: Developmental Dyslexia
Difficulty in learning to read below standard appropriate to age
No issue with spoken language
Hereditary component
Phonological impairment: decomposing words into individual sounds (phonological word representations)
Phonological awareness
which words start with a different sound: bit, bat, cat? Say “cat” without the first sound, what word rhymes with “pie”?
Deficits: non-word repetition, naming pictures (expressive vocabulary), phonological working memory
Surface dyslexia/ dysgraphia
Overreliance on dorsal route (grapheme- to-phoneme conversion) due to damage in ventral route
Sounding out written letters
Surface dyslexia/dysgraphia is observed in semantic dementia
Link of word form to meaning is damaged
High-frequency words may have some semantic support
Phonological dyslexia (acquired)
Fine visual lexicon and comprehension, but can’t pronounce unfamiliar words
Familiar words are read better than non-words
Non-words are misread as a familiar word
“fint” > /fine/; poat > /boat/
Short-term memory for speech sounds and manipulation of sounds (phonological buffer)
Impaired grapheme-to-phoneme conversion in reading or writing
Deep dyslexia/dysgraphia
Unable to read non-words
Better at reading concrete words than abstract words (imageability effect)
Poor reading of function words (the, a, of)
Make characteristic errors
Convergence between functional organisation of cognitive models and the reading brain
Taylor, Rastle & Davis (2013): Meta-analysis of 36 neuroimaging studies - word vs. pseudoword reading activation - to relate cognitive model components to anatomical structures.
