Science2 publishers2 min readPublished
Children with dyscalculia clung to slower counting methods as the problems got harder
A Stanford team recorded which route 68 children aged 8 to 10 took through arithmetic problems and imaged their brains, and the children with dyscalculia were slow to change method and never got better at choosing.
The Scientist · Science desk
What happened
- A Stanford team led by Oliver Lasnick reported in The Journal of Neuroscience on how children with developmental dyscalculia choose arithmetic strategies and how their brain networks coordinate that choice.
- Among 68 children aged 8 to 10 working problems of varying difficulty, those with dyscalculia took significantly longer to move from one computational method to another.
- Over repeated trials the same children did not get better at picking the ideal strategy for a problem, and often stayed with a slow procedure when the problem grew harder.
- Developmental dyscalculia affects roughly 5% to 7% of school-aged children, who struggle with arithmetic despite normal intelligence and standard schooling.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- constraint Because the brain and behaviour measures come from the same children observed once, the study cannot separate a control deficit that caused years of slow arithmetic from a habit those years produced, and the researchers' own wording leaves the direction open.
- decision Anyone designing a remediation study now has a per-child outcome to score: how long a child takes to change method, and whether strategy choice improves across trials, alongside accuracy on fact recall.
- precedent Lasnick's emphasis on individual variability points the next round of work toward subtypes, since a single group average describes children whose cognitive profiles he says differ.
Each child in the Stanford cohort worked arithmetic problems that varied in difficulty while the experimenters recorded the method used on each one: direct fact retrieval, decomposition, or iterative counting on fingers or in the head [3]. Earlier dyscalculia research concentrated on how children represent number in the first place [10]. Scoring the route to the answer, and how long a child stays on it, makes a switching deficit visible.
The flat learning curve is the strongest result. Across repeated trials, the children with dyscalculia did not improve at selecting the best strategy for a given problem [6]. A child who cannot recall a sum can still learn which route to it is quickest. The Stanford group places the difficulty in cognitive control circuits that govern strategy selection and flexible problem solving [13], and describes the profile as interconnected dysfunction across attention, executive working memory and cognitive flexibility [14].
The write-ups do not report how many of the 68 children had the diagnosis [15]. Developmental dyscalculia affects roughly 5% to 7% of school-aged children [9], so a random sample of 68 eight- to ten-year-olds would be expected to hold about three to five of them [16].
Brain-system activity differed between the children with dyscalculia and those who were more proficient with math strategies [7], and according to the phys.org account it predicted how well children counted and how well they switched methods [8]. The neural measure and the behavioural measure come from the same children, so the analysis establishes that the two covary. The researchers keep the direction open: they say persistent struggles with problem-solving strategies and with controlling attention, thinking and memory may lead to the onset of the condition, and point to altered brain activity that may drive those behaviours [12].
This design cannot answer whether teaching flexible strategy use would help these children more than practice at fact recall. Ranking two approaches means assigning children to each and measuring arithmetic later. These data show how two groups of eight- to ten-year-olds differed on one task and in one set of brain measures [1].
Oliver Lasnick, who led the study, said: "Importantly, this study also emphasizes the individual variability observed in dyscalculia, further demonstrating that the disorder reflects cognitive and neural dysfunction across multiple processes" [11].
What to watch
- Whether the full JNeurosci paper reports the size of each group and effect sizes for the switching measures.
- A randomized trial that trains flexible strategy use in children with dyscalculia and measures arithmetic months later.
- Whether follow-up work splits the dyscalculia group into subtypes instead of comparing one group average.