Parallels in stimulus-driven oscillatory brain responses to numerosity changes in adults and seven-month-old infants.

Previous studies provide indirect evidence for an ontogenetically continuous Approximate-Number System. We employed a rapid steady-state visual-presentation paradigm combined with electroencephalography to measure stimulus-driven neural oscillatory responses to numerosities in infants and adults. Steady-state repetition of the same numerosity across a 2.4-sec time block yielded an increase in the stimulus-locked neural entrainment in both groups. Entrainment changes following a numerosity switch varied by the ratio of the numerosities, consistent with Weber's Law. These similarities thus provide direct evidence for an ontogenetically continuous Approximate-Number System. Moreover, the degree of neural entrainment significantly predicted infants' number discrimination measured behaviorally two months later.