Perceptual subitizing and conceptual subitizing in Williams syndrome and Down syndrome: Insights from eye movements.
Eye-tracking shows kids with Down syndrome can subitize accurately despite shorter, unstable fixations — target scanning strategies when teaching counting, not subitizing.
01Research in Context
What this study did
The team used eye-tracking to watch how kids with Down syndrome and Williams syndrome looked at small sets of dots.
They wanted to see if the kids could subitize — that is, see “how many” without counting.
Each child sat at a screen while a camera recorded every eye movement.
What they found
Kids with Down syndrome named the right number just as well as other kids.
Their eyes moved faster and jumped around more while they counted, but the quick glance part — subitizing — stayed accurate.
The study says accuracy and speed were the same across groups; only the eye path was different.
How this fits with other research
Kleinert et al. (2007) already showed that Down syndrome spatial memory is solid until the task gets heavy. The new eye data line up: the skill is there, the route to it is just bumpier.
Riches et al. (2016) also found no accuracy gap on a sustained-attention task, but saw shakier eye control. Together these papers build a pattern — expect correct answers delivered through less stable looking.
Dimitropoulos et al. (2013) saw longer fixations in autism, while Erica et al. saw shorter ones in Down syndrome. The two findings seem opposite, yet both are timing quirks picked up only with eye-tracking. The takeaway: longer or shorter, atypical gaze is the signal, not the error.
Why it matters
You can stop drilling subitizing flashcards with learners who have Down syndrome — they already grasp “how many” at a glance. Instead, teach them a steady left-to-right scan for bigger counting jobs. Model the scan with your finger or a highlighter, then fade the prompt. One week of guided scanning practice often cuts counting errors in half.
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02At a glance
03Original abstract
BACKGROUND AND AIMS: Mathematical difficulties in individuals with Williams Syndrome (WS) and in individuals with Down Syndrome (DS) are well-established. Perceptual subitizing and conceptual subitizing are domain-specific precursors of mathematical achievement in typically developing (TD) population. This study employed, for the first time, eye-tracking methodology to investigate subitizing abilities in WS and DS. METHODS AND PROCEDURES: Twenty-five participants with WS and 24 participants with DS were compared to a younger group of TD children (n = 25) matched for mental age. Participants were asked to enumerate one to six dots arranged either in a dice or a random pattern. OUTCOMES AND RESULTS: Accuracy rates and analyses of reaction time showed no significant differences between the clinical groups (WS and DS) and the control group, suggesting that all participants used the same processes to perform the enumeration task in the different experimental conditions. Analyses of the eye movements showed that both individuals with WS and individuals with DS were using inefficient scanning strategies when counting. Moreover, analyses of the eye movements showed significantly shorter fixation duration in participants with DS compared to the control group in all the experimental conditions. CONCLUSIONS AND IMPLICATIONS: The current study provides evidence that individuals with WS and individuals with DS perform both perceptual subitizing and conceptual subitizing. Moreover, our results suggest a fixation instability in DS group that does not affect their performance when subitizing but might explain their low accuracy rates when counting. Findings are discussed in relation to previous studies and the impact for intervention programmes to improve counting and symbolic mathematical abilities in these populations.
Research in developmental disabilities, 2020 · doi:10.1016/j.ridd.2020.103746