NC4 Flashcards
Characteristics of MLD/DD
Math skills (3)
- Not unitary
- Large inter-individual diffs.
- Different trajectories
- Low performance on test
Characteristics of MLD/DD
MLD/DD is not unitary. What does this mean?
Might be excellent at one aspect of math but struggle with another
Characteristics of MLD/DD
“Large inter-individual differences” what does this mean?
Children of the same age will exhibit different characteristics of MLD/DD
Characteristics of MLD/DD
“Different trajectories in different children.”
What was the method?
4 assessments over 2 years (5-7 y/os)
Characteristics of MLD/DD
“Different trajectories in different children.” (Jordan et al., 2009)
What was found?
Linear/quadratic/sigmoidal + flat trajectories
Characteristics of MLD/DD
“Different trajectories in different children.”
What is the exclusion criteria? (3)
Low performance must not be explained by bad education/neurology/psychiatry
Severe math difficulties, i.e.
DD (Development Dyscalculia)
How many children are estimated to have DD?
3%-10%
Less severe mathematical difficulties might affect
Education/occupational outcomes
__% of children have MLD (mathematical learning disorder)
25
Which term is used to describe the more severe math difficulty conditions?
DD
Developmental Dyscalculia
Dyscalculia is a ______ condition, and different ______ have been proposed
Heterogenous
Subtypes
Have the subtypes of DD received empirical validation?
No
Comorbidity of DD
Between 1/2 and 2/3 of DD children have an additional learning disorder
Moll et al., 2015
Between 1/2 and 2/3 of DD children….
Suffer from additional learning disorder
4 disorders associated with DD
Reading difficulties
ADHD
Language delay
Motor deficits
Reduced ______ in MLD/DD
Subitizing
Moeller et al., 2009
Subitizing in MLD/DD
Findings (3)
- Reduced 1-3 subitizing
- Increased fixations
- Evidence of counting
Why might children with MLD/DD have counting difficulties?
- Delay in acquisition of principles
2. Slower in counting/reciting
Geary et al., 1999
Counting errors
Findings (1)
Children with DD reported PSEUDO ERRORS as INCORRECT and REAL ERRORS as CORRECT
PSEUDO ERROR
E.g. counting right-to-left
REAL ERROR
Double counting
Bugden + Ansari (2016)
ANS acuity reduced in MLD/DD, especially…
If the stimuli was incongruent
Incongruent stimuli is an example of
A confounding perceptual cue
Bugden + Ansari (2016)
____ acuity reduced in MLD/DD
ANS
De Smedt + Gilmore, 2011
How are MLD/DD children when symbolic number processing?
Poor performance (slower RTs)
De Smedt + Gilmore, 2011
What about non-symbolic number processing? (2)
Similar performance across DD/TD
DD still worse
Size congruity effect –>
DD children need longer to access numerical magnitude info
Geary et al., 1999
Transcoding
Reduced ability to name/write numbers when presented in another modality (transcoding)
Children with MD are less accurate in identifying and ______ numbers
Transcoding
If a child struggles to name a number read out loud to them, they struggle with
Number identification + transcoding
Number line task –>
Worse performance in DD children
DD children were worse at number fact retrieval than… (2)
Dyslexics
Control
In terms of strategy use, DD children are more likely
To use immature strategies
Geary (1990)
What strategies are DD children likely to use when solving problems
Finger counting
Kaufmann et al., (2011)
Sometimes the use of fingers
Persists into adulthood
Chan + Ho, 2010
When do children with DD move onto direct retrieval of learned strategy?
Significantly later than TD children
Chan + Ho, 2010
Children with DD move later from counting on fingers to…
Direct retrieval of the learned strategy
Place-value understanding
DD children have poor understanding
Understanding, for example the ‘tens digit’ in a number means understanding
Place-value
Lander 2013, Chan + Ho 2010
Place-value understanding
DD children display higher error rates when
Comparing large numbers in an INCOMPATIBLE condition
Theories have been categorised into 2 groups:
Domain-specific theories
Domain-general théories
Currently there is no agreement on the _________ of DD
Core cognitive deficit
What evidence is there to suggest that both domain-specific and domain-general theories might be right?
Many DD children show impairments in BOTH functions (Cowan + Powell, 2014)
Domain-specific theories believe the core deficit of DD is
Numerical
Domain-general théories believe the core deficit of DD is
Non-numerical mechanisms (that are important for number processing)
2 Domain-specific theories
ANS deficit
Symbolic number processing (access) deficit
Domain-specific theory
ANS
Children with DD
Have impairment in the ANS (low number acuity, large weber fraction)
Domain-specific theory
ANS
Having low number acuity can lead to a
Weak representation of number words
Domain-specific theory
ANS
Methodological issue regarding this theory?
Not all studies find a relation
Domain-specific theory
Symbolic number processing
Children with DD
Have difficulties accessing numerical magnitude info (symbolic)
Domain-specific theory
Symbolic number processing
DD children have difficulties accessing symbolic magnitude info. This is shown by
Slow RTs in digit comparison tasks
Two domain-general theories of DD
LTM
Working memory
Working memory is subdivided into (3)
Verbal WM
Visuospatial sketchpad
Central executive
Verbal working memory a.k.a
Phonological loop
Domain-general theory
LTM
How might DD be affected by memory?
Difficulties memorising arithmetic facts
Domain-general theory
LTM
Critical Evaluation (2)
Little evidence: DD children can encode/retrieve non-numerical content
Visuo-spatial sketchpad is responsible for what kind of math problem?
Written arithmetic problems
Verbal working memory (phonological loop) is responsible for what kind of math problem?
Number facts retrieval/holding in memory-partial results
Strongest evidence for VS deficit or V WM deficit?
Visuospatial WM
Domain-general theory
Out of verbal WM and visuospatial WM deficit theories, which has the weakest evidence?
Verbal WM
Math problems
How is central executive involved? (3)
Complex procedures
Overlaps with inhibition/attention
How might central executive be involved in WM-deficit DD theories?
Overlaps with inhibition and attention, which might be compromised in DD
