Lecture 6: Dyscalculia and Dyslexia Flashcards
specific learning disability: traditionally
- (USA: IDEA 1999): Discrepancy of 1-2 standard deviations between intellectual functioning (IQ) and academic functioning (e.g. smart children who unexpectedly cannot read or do math)
- Problematic: How much discrepancy is arbitrary/Older and higher IQs are favoured/Failure based (“waiting to fail”)
modern view on specific learning disability
- Moving towards identification with Response to Intervention (RTI), see IDEA, 2004
- Achievement in key academic areas (reading, writing & arithmetic) is substantially below age norm and in excess of sensory deficit, linguistic processes, attention and memory
*Prevalence rates: 2-10% of population
response to intervention (Seidenberg)
- Tiered system (dus in lagen), empirically supported interventions, failure to respond => criterium for identification of SLD and more specific and intensive intervention
1. Screening for risk: simple tests basic prereading skills
2. family history reading/language difficulties
3. Tier 1 intervention: high quality classroom teachers
4. Tier 2 intervention: additional 1-1 instruction/small groups
5. Tier3 intervention: dyslexia specialist outside of school (but not yet special education)
prevalentie problemen met lezen
Poor readers (25%)
Children with serious reading problems (8,8%)
Children who do not progress and resist intervention (3,6%)
current definition of SLD in DSM
- Difficulties learning and using academic skills, as indicated by the presence of at least one of the following symptoms (see “Impairment in Reading” and “Impairment in Mathematics” later) that have persisted for at least 6 months, despite the provision of interventions that target those difficulties
- The affected academic skills are substantially and quantifiably below those expected for the individual’s chronological age, and cause significant interference with academic or occupational performance, or with activities of daily living, as confirmed by individually administered standardized
achievement measures and comprehensive clinical assessment. For individuals age 17 years and older, a documented history of
impairing learning difficulties may be substituted for the standardized assessment. - The learning difficulties begin during school-age years but may not become fully manifest until the demands for those affected academic skills exceed the individual’s limited capacities
(e.g., as in timed tests, reading or writing lengthy complex reports for a tight deadline, excessively heavy academic loads). - The learning difficulties are not better accounted for by intellectual disabilities, uncorrected visual or auditory acuity, other mental or neurological disorders, psychosocial adversity, lack of proficiency in the language of academic instruction, or inadequate educational instruction. So Differential Diagnosis needed!!!!
Note: The four diagnostic criteria are to be met based on a clinical synthesis of the individual’s history (developmental, medical, family, educational), school reports, and psycho-educational assessment.
specifiers for SLD
- mild (some difficulties in 1 or 2 domains)
- moderate (marked difficulties in 1 or more domains)
- severe (severe difficulties in several domains)
SLD and internalizing problems
- meer anxiety
- competence is biggest cocnern
- social skills deficits
- poor self concept
- lack of self esteem
can changing your mindset help?
- bv PPI’s (enhance wellbeing by increasing positive affect, cognition and behaviours)
- coping skills can help and make a difference
- but not sufficient: not all dyslectics have unique strenghts, and their problems need to be addressed
- Mindset can make a difference, but it is important to focus on the remediation and work on the obstacles in learning difficulties
how do you learn to read
- concept <-> spoken sound
- written word <-> sound <-> concept
word representations
semantics (meaning) - orthography (spelling) - phonology (sound)
driehoek, zie schrift
Ehri’s phases of word-reading development
- prealphabetic (visual features)
- early alphabetic (know some letter-sound correspondences)
- later alphabetic (recognize some words from memory, phoneme-grapheme correspondences, blending words)
- consolidated alphabetic (automatic vocab, patterns)
but always interaction between letters, syllables and words
integration between orthography and phonology: normal development
- children: letter by letter decoding (priming studies show no fast automatic phonology)
- adults: parallel activation of letters (priming studies do show fast automatic phonology) -> words are read faster (word superiority effect), we still read all individual letters but very fast
integration between orthography and phonology: dyslexia
decode letter by letter longer, problems in integrating letters and sounds which is central for reading
orthographic learning
- Words you have already heard: /jam/
- You read a text: I eat jam
- Decoding necessary: from visual to auditory code
- I eat a sandwich with a) jem b) jam
self-teaching
door context weet je wat het is
prevalence dyslexia and poor readers
dyslexia = 3.6%
poor readers = 8.8%
co-occurence of dyslexia in family
- siblings: 40%
- one parent: 23-65%
- twins: 70%
etiology of dyslexia
- left hemisphere posterior brain ssytem
- visual word form area
spelling is harder than reading because…
you need to be precise
reading impairment DSM
- inaccurate or slow and effortful word reading
- difficulty understanding the meaning of what is read
- difficulties with spelling
specifiers:
- word reading accuracy
- reading rate or fluency
- reading comprehension
Dutch Health System: criteria for dyslexia
- severe reading and spelling problems:
- A1: most severe problems in word reading (<-1.5 SD), less in pseudoword (<-1.28 SD)
- A2: most severe problems in pseudo word reading (<-1.5 SD) and also severe word reading (-1.28 SD)
- B1: most severe in spelling (<-1.5 SD), also severe in word reading (<-1.28 SD) - persistent reading problems and possible spelling problems despite adequate education, additional support, and at least 6 months receiving specific individual training
- not due to a general learning problem, broad neurological problems or severe sensory problems, e.g. in sight, hearing
Definition: No IQ reading discrepancy but below age expected levels
-> reading difficulties are identified in children and the limitations of relying solely on an IQ-reading discrepancy model
- poor readers can have different IQ levels but still the same behavioural characteristics 2. IQ not a strong predictor of intervention responses
- Reading ability and IQ are continua: discrepancy boundaries are arbitrary
- Low end of normal reading distribution: severe reading difficulties, treatment needed
- No dyslexia if secondary to other problems: very low IQ or hearing problems or bad schooling
lower end of the continuum: is this pathological?
- Many beginning readers falling behind age group catch up with ordinary support and effort. Dyslexics do not grow out condition and problems multiply
- Like other conditions on a continuum: Hypertension, Obesity, Addiction
- Identification and targeted treatment important for well-being, health and success (reading is culturally important)
- So purposeful medicalization! (= ensure that children get support)
characteristics of dyslexia
- Difficulties in reading
- Problems in decoding (sound-symbol association): phonological deficit
- Comprehension problems
- Fluency problems: leads to memory consolidation problems
- Negative effects on word identification (Word blindness!) and passage comprehension
- Reading is foundation for learning about the world!
- Non-fluent reading => less learning, so possible Matthew effect
Phonological deficit theory:
Simple phonological processing (sound-symbol association) -> Less awareness of sound structure -> Problems in making connections between spoken and written language
Phonological awareness=
- Awareness of the sound structure of words (phonemes)
- the sounds are central, not the letters!
- What is /stall/ without /s/ sound?
- Interchange the first letters of each word: ‘Winnie the pooh’
possible explanation for lack of phonological awareness
- Possible explanation: Underspecified word
representations (low quality/not sufficiently
specific /discriminative) - This suggests that the representation of the word “hek” is underspecified, meaning its phonological encoding lacks sufficient detail to be clearly distinguished from similar-sounding variants like “hok,” “hak,” “hes,” “gek,” “bek,” “hel,” and “hik.”
pseudowords
- words that could have existed (kes, woeg)
- decoding is essential: no word representations in memory/brain
- good test for adult dyslexics
Simple view of reading
phonological decoding * Language comprehension = reading comprehension
Language comprehension without reading refers to listening comprehension, as it involves understanding language solely through auditory input rather than visual text.
oke
Phonological decoding=
associating sound to the symbol (‘Technisch lezen), measured with Een Minuut Test or One Minute Test
Reading comprehension is conditional on ….
both phonological decoding and Language comprehension
Slow decoding leads to…
=> slow word reading fluency => poor reading comprehension
why is fast decoding important?
- according to Baddeley’s model, the phonological loop—a component of working memory that temporarily holds verbal information—has limited capacity, so when decoding is slow, too much cognitive effort is spent on holding individual words in memory rather than processing the overall message.
- Bottleneck theories, such as the Verbal Efficiency Theory, further support this idea by suggesting that when basic word recognition processes are efficient, the cognitive system can allocate more resources to higher-level tasks like syntactic processing and making inferences. This means that efficient decoding not only speeds up the reading process but also improves comprehension by freeing up mental capacity to integrate information across sentences and grasp more complex ideas.
hoe ontwikkelt leesvaardigheid zich in mensen met dyslexie?
- Many Dyslexic readers become accurate readers: they do improve over time!
- Yet.. Fluency problems are more persistent: effortful, slow and laborious reading
- Fluency is hard to remediate even with intensive and specialized instruction
- Essential to remediate reading fluency
double deficit theory=
Deficit 1: Phonological awareness problems
Deficit 2: Speed problems (RAN/naming tasks ‘benoem taken’)
* Children can have a. only phonological problems/b. only RAN problems/c. phonological and RAN problems
* Phonological + RAN problems = double deficit, resulting in more severe problems
rapid naming =
ease of access to representations stored in memory
bv. zo snel als mogelijk kleuren opnoemen, of logo’s
How Dyslexia manifests itself in different
languages
- Deficits in phonological awareness and rapid naming predict dyslexia across orthographies
- Deficits in phonological awareness are more predictive in opaque orthographies such as English and Danish
- Deficits in rapid naming are more predictive in more transparent orthographies such as Dutch and German
transparent vs. opaque orthographies
transperant: highly consistent grapheme-phoneme correspondence, meaning that each letter or letter combination almost always represents the same sound
opaque: have less consistent or predictable letter-sound relationships. The same letter or combination of letters may produce different sounds in different words, and sounds may be represented by various letters.
prevalence and heritability of dyscalculia
- Prevalence: 5% to 10%
- Heritability: 43%
dyscalculia=
- Limitations in mathematical understanding
- Deficit in Number sense; e.g. Mental Number line
- Impedes activities that involve problem solving or retrieving mathematical information (number facts)
- Problems in acquisition of number sense because of poor Approximate Number System
approximate number system=
- A portion of your cognition that is active across your entire life
- Gives a rapid and intuitive sense for numbers and their relations (e.g., how many blue versus yellow dots are on a screen
dyscalculia dsm 5
- difficulties mastering number sense, number facts or calculation
- difficulties with mathematical reasoning
specifiers dyscalculia
- number sense
- memorization of arithmetic facts
- accurate or fluent calculation
- accurate math reasoning
the triple code model (Dehaene)
in math 3 codes need to cooperate: two symbolic and 1 non-symbolic:
1. An auditory verbal code (/three/) = symbolic -> arithmetical facts learned by rote (addition, multiplication)
2. A visual code for Arabic digits (3) = symbolic -> parity judgements (two = 2) and multidigit operations
3. An analog magnitude code (e.g. *** vs ** vs **) = non-symbolic -> magnitude comparison & approximate calculation
Defective Number Module Hypothesis
This hypothesis posits that the problem lies in the fundamental representation of quantity itself—both in nonsymbolic (analog magnitude) forms and in symbolic forms (actual numbers). Essentially, individuals with this deficit struggle with processing quantities at a basic, underlying level, meaning their difficulties are broad and affect both symbolic and nonsymbolic numerical processing.
Access Deficit Hypothesis
In contrast, this hypothesis suggests that the core issue isn’t with the representation of quantity per se, but with accessing that quantity information through symbols. That is, the nonsymbolic representation of quantities (analog codes, ***) is intact, but the problem occurs in mapping or retrieving that information when it is presented in a symbolic format (like Arabic numerals, 3).
symbolic numerical magnitude comparison
a visual code for arabic digits
welke is groter: 1 / 9
numerical magnitude comparison analog
non symbolic
waar zitten meer gele vierkantjes in
De Smedt studie
3 groups:
* Children with severe mathematics learning
problems (MLD)
* Children with mild mathematics learning disabilities (low achievement or LA)
* Regular achievers (Typical Achievers or TA)
- Compare by Numerical magnitude comparison: symbolic (Arabic digits) and non-symbolic (Dots)
- Compare by Approximate addition (Dutch: ‘Schattend optellen’) : symbolic (5 +5 vs 50) and non-symbolic (5 dots + 5 dots vs 50 dots)
Numerical magnitude comparison:
* Symbolic task: MLD (severe mathematics learning problems) slower than regular TA, LA and TA no difference
* Non-Symbolic task: no group differences
Approximate addition (‘Schattend optellen’)
* Symbolic task: Regular TA more accurate than LA and MLD (LA = MLD)
* Non-Symbolic task: no group differences
conclusion:
Young children with Math problems (Severe and Mild) have specific problems with symbolic tasks and not with number in general (‘hoeveelheid’)
=> Evidence for Access deficit hypothesis
two hypotheses for comorbidity between dyslexia and dyscalculia
Common deficit: dyscalculia is also caused by
phonological problems, partial overlap in problems so less problems in total in comorbid group
Domain-specific: dyscalculia specific problem in number module, unrelated to dyslexia: problems are additive in comorbid group
design and results Landerl
- Control children (TA), Only Dyslexia, Only
Dyscalculia, comorbid Dyslexia and Dyscalculia - Typical Dyslexia diagnosis tasks: phonological
awareness, RAN etc. - Typical Dyscalculia diagnosis tasks: Comparison
tasks (both symbolic and nonsymbolic magnitude
comparison), number line etc - Typical Dyslexia tasks: problems only in Only
Dyslexia and Comorbid groups (also RAN digits!) - Typical Dyscalculia tasks : problems only in Only Dyscalculia and Comorbid groups
Comorbid group:
* Additive and both problems
* Problems appear independent from eachother
* Domain specific explanation
nonverbal learning disabilities (NLD)
Opposite profile from Dyslexia: significant strengths in verbal areas (e.g. single word reading) yet significant weaknesses in performance areas (visuospatial)
- Unclear how symptoms relate: perception and attention?
- No explanatory theory: white matter problem in right hemisphere not sufficient evidence
- Not clear what are essential characteristics: classification diagnosis impossible
- Not in DSM because no reliable and valid diagnosis. Label leads to tunnel vision and too limited selection of tests
voorbeeld case:
* Problems with learning from visual information (Pictures)
* Good at learning new words
* Poor ‘visual-constructive’ skills = difficult to translate what she sees in a motor response (e.g. build Lego from an example)
* Attention problems when visual information is offered
- The reliable and valid diagnosis of a symptom is problematic but the problems are real and children need help!
- Psychologists needs to establish a profile of strengths and weaknesses and do a differential diagnosis (what is it and what not)!
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