Groupitizing modifies neural coding of numerosity

Area of Science:

• Cognitive Neuroscience
• Neuroimaging

Background:

• Numerical estimation is enhanced by grouping objects, a process known as "groupitizing."
• Grouping allows for subitizing small sets and summing estimates, improving accuracy and speed.

Purpose of the Study:

• To investigate the neural basis of spatial grouping in numerical estimation.
• To determine if grouping strategies recruit distinct brain regions beyond those involved in basic numerosity processing.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to scan 14 adults.
• Participants estimated the numerosity or shape of randomly distributed or spatially grouped arrays.
• Multivariate pattern analysis (MVPA) was employed to decode neural patterns.

Main Results:

• Numerosity estimation of both random and grouped arrays activated a right frontoparietal network.
• Spatially grouped stimuli additionally recruited left hemisphere regions and the bilateral angular gyrus.
• Parietal neural patterns, not visual cortex patterns, decoded numerosities, and this correlated with behavioral acuity.

Conclusions:

• Spatial grouping in numerical estimation engages the approximate number system and recruits additional brain regions associated with calculation.
• The findings suggest a neural basis for how grouping enhances numerical cognition.