Developmental Changes in Nonsymbolic and Symbolic Fractions Processing: A Cross-Sectional fMRI Study

Area of Science:

• Cognitive Neuroscience
• Developmental Psychology
• Educational Neuroscience

Background:

• The neuronal recycling hypothesis suggests that the brain repurposes existing neural architectures for new cognitive functions.
• Prior research indicates humans and animals can process nonsymbolic ratios, which may form a foundation for understanding symbolic fractions.

Purpose of the Study:

• To investigate if children possess neural sensitivity to nonsymbolic fractions before formal instruction.
• To determine if children leverage nonsymbolic processing networks for symbolic fractions acquisition.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to compare nonsymbolic and symbolic fractions processing in 2nd and 5th graders.
• Children performed ratio comparison tasks involving both nonsymbolic and symbolic fractions.

Main Results:

• Both age groups processed nonsymbolic and symbolic fractions, with performance influenced by numerical distance.
• 2nd graders used a right parietal-frontal network for nonsymbolic fractions only, while 5th graders used a bilateral network for both.
• Neural similarity between nonsymbolic and symbolic processing was higher in 5th graders, particularly in the intraparietal sulcus.

Conclusions:

• Neural substrates for nonsymbolic ratio processing exist in children before formal fractions instruction.
• Symbolic fractions processing appears to build upon these pre-existing nonsymbolic neural networks.
• Educational strategies supporting this neural recycling may improve symbolic fractions understanding.