Dyslexia Flashcards
how do we read?
by decoding words - when reading irregular words try and use the sounds
dyslexia history
1896
- Percy - 14 year old boy - inability to read due to deficit storing visual representations of whole words –> congenital word blindness
1925 - perceptual disorder - twisted symbols
DSM 5
has to be bwloe age level
inaccurate or slow and effortful word reading
have to have attempted and failed
refers to specific impairment in reading
- problems with: poor word recognition, decoding + spelling
- ENGLISH - inaccurate and slow single word reading
- other languages - reading accurate but slow
lots of risk factors - combination
who diagnoses and when?
educational psychologists - 8 years old
-heritable - environment provided
The rose review 2009
influential in how people viewed + approached dyslexia
- is a language learning disorder
-learning difficulty that affects the skills involved in accurate + fluent word reading
difficulties:
-PA, verbal memory, verbal processing speed- RAN task
continuum
-cooccuring difficulties in language, motor skills, mental calculation, concentration, personal organisation
how severe + persistent - how well intervention respond
Early school manifestation
- letter sound learning
- PA
- decoding
- spelling
- probems copying
middle school manifestation
slow reading
decoding
phonetic or non spelling
adolescent
poor spooners test
reading fluency
slow writing
organisation
Cognitive theories:
Visual theories:
motion processing/attention
- difficulty forming visual impressions
- word blindness
- twisted symbols
Magnocellular deficit: sensory/perceptual
- visual cells detect motion
- auditory cells detect changes
visual magnocellular system
-sensitive to motion
-RDK TESTS TO ASSESS function (motion vs fine details - parvo)
-see display of dots - how sensitive = how many dots need to be moving to detect the movement
dyslexic - poorer motion detection
affects reading - achieving perceptual stability
- have to coordinate eyes to work together to focus on one thing at a time
- if poor motion sensitivity - unsteady binocular vision leads to visual stress difficulties - cover one eye to treat
EVIDENCE FOR THEORY
Stein - visual symptoms dont affect all
-RDK only comes from one research group
-doesnt correlate well with reading or non word reading
Coloured overlay/lenses -certain colours speed up processing in magno pathway hawthorne effect -risk of bias -no control group
Auditory magnocellular system
domain general sensory deficit
-phonemes differentiated by rapid changes in frequency and amplitude
>phoneme difficulty?categorical deficit?phonological deficit=decoding words very hard
FM+AM tasks - what degree of modulation necessary to be detected
- more mod needed to detect
- correlated with PA
links with ceebellum
- involved incontrol of timing - muscle + eye movemens
- tumours have reading difficulties
Visual attention - Valdois
briefly show series of letters + ask if was present
-unique predictor of reading scores
Ziegler 2010
dyslexic - deficits in letter not symbol task
-problem converting symbols to verbal labels
video games - intervention study
improves visual attention
-improves reading difficulties
Gori 2016
group comparison - RDK moving circles - dyslexic poorer motion
assessing high risk but not diagnosed - poor readers worse
intervention study - faster nonsense reading after intervention
PHonological deficit hypothesis
PA correlates with reading + predicts growth
- poorer at phonological tasks
- learning to read improves phonologucal skills
Meta analysis of risk studies
have more severe preschool language difficulties
poor vocab + phonological memory persist
dyslexic FR - poor PA + RAN
dont become dyslexic - weak PA
evidence for endophenotype
Hulme 2015
intervention
-PA + LSK mediated gains in reading
speech perception
what causes phonological deficit? underlying problem in speech or auditory perception
- poor categorical perception
- allophonic perception - heightened perception of differences within cat
- less clear boundary but extra sensitive to differences at ends
-speech percep performance didnt correlate with phonological tasks or decoding
Auditory processing
Rapid auditory temporal processing decifit
deficit processing rapid auditory changes - short or gaps
frequency detection deficit
less sensitive to frequency differences to distinguish phonemes
onset rise time
less sensitive to amplitude changes - prosody
risk studies: auditory processing
finnish - sounds + ERP
- differences right hemisphere
- related to oral laguage 2.5yr
