Mental math's shortcut—pupil dilation suggests people start solving before all numbers are in

People often solve simple arithmetic problems, such as basic addition, subtraction, multiplication or division, in their minds. The precise mental processes they rely on to solve these problems, however, are not entirely clear. Researchers at Université de Bordeaux and UCLouvain recently tried to better understand how humans tackle simple math mentally by tracking the size of their pupils.

source https://phys.org/news/2026-04-mental-math-shortcut-pupil-dilation.html