Numerical and nonnumerical estimation in children with and without mathematical learning disabilities

Area of Science:

• Cognitive Psychology
• Developmental Psychology
• Neuroscience

Background:

• Mathematical learning disabilities (MLD) have multiple proposed explanations.
• A prominent theory suggests MLD stems from deficits in representing and manipulating number magnitude or accessing this representation from numerical symbols.

Purpose of the Study:

• To investigate the numerical abilities of children with MLD using tasks involving both symbolic (Arabic numerals) and nonsymbolic (dot collections) number formats.
• To determine if MLD is associated with a basic numerical deficit, specifically in number magnitude representation and symbolic-nonsymbolic mapping.

Main Methods:

• Carefully selected children with MLD and control children performed numerical estimation tasks.
• Tasks involved contrasting symbolic and nonsymbolic numbers as input or output, including mapping between formats.
• Performance was assessed on accuracy and reliance on perceptual cues.

Main Results:

• Children with MLD were less accurate than controls across all estimation tasks.
• MLD children showed greater deficits when mapping between symbolic and nonsymbolic numbers compared to nonsymbolic-nonsymbolic mapping.
• MLD children relied more on perceptual cues (e.g., dot area) for nonsymbolic numerosity estimation.
• Mapping from nonsymbolic to symbolic format best predicted MLD.

Conclusions:

• The findings support the hypothesis that MLD is linked to an impoverished number magnitude representation.
• An initial deficit in mapping number symbols to magnitude representations may underlie MLD.
• These results provide a unified explanation for existing literature on MLD.