A brain imaging experiment found a shared organization for fractions and integers while adults compared their values. Nearby numerical magnitudes elicited related patterns in parietal brain regions. The peer-reviewed study used a small, educated sample; it leaves open whether the task strengthened an existing representation or encouraged participants to construct one.
Science··Night
Quantities share a cortical arrangement
Fractions and integers followed a shared brain map when adults compared their numerical values. In a peer-reviewed imaging experiment, nearby magnitudes elicited related activity patterns in the anterior inferior parietal cortex, part of the brain’s number-processing network. The common arrangement appeared during a task that required participants to focus explicitly on magnitude.[1], [2]
Participants saw numbers in sequence and indicated whether each was larger or smaller than its predecessor. The stimuli comprised 6 integers and 6 fractions. Comparisons were harder when values were close together, and participants were slower and made more errors with fractions. The researchers examined both numerical magnitude and the distinction between the two number formats.[1]
Two runs test the pattern
The imaging analysis included 20 adults, while behavioural analysis included 19 because one response button failed. All were right-handed native French speakers with a scientific high-school background. Imaging used a 7-tesla scanner at 1.2 mm resolution. The team located mathematics-responsive regions independently with a task containing no numerals, separating region selection from the main comparison.[1]
Numerical preferences identified in one run were tested against activity in the other; the runs then exchanged roles. This reduced dependence on choosing and confirming the same pattern from one dataset. The analyses also corrected for multiple comparisons. Similar magnitude preferences appeared in nearby cortical locations for both fractions and integers.[1]
The study initially recruited 22 healthy adults. One participant with a temporal-lobe cyst was excluded; another left the experiment following a panic attack in the scanner. The response buttons exchanged meanings between runs, and eligible transitions between numbers appeared equally often. The authors also report that the curved geometry depended on the analytical representation: a simpler principal-component analysis yielded a one-dimensional organization.[1]
The task and numerical range matter
Fractions and integers covered different ranges, but removing the largest integers preserved the main result. The authors note that alternating the formats may have encouraged construction of a common number line. An existing representation strengthened by the task and a representation assembled during it remain possible explanations. Data, code and outputs for reproducing the main findings are publicly available.[1]
Related columns
For more information on this topic, you can read the related columns.
