The development of number symbol processing: A fast periodic visual stimulation study

In our cultures the meaning of number symbols is acquired and reinforced through education. Accordingly, it is critical to understand how children become experts in the use of Arabic numbers (AN).
Here, we used fast periodic visual stimulation (FPVS) combined with a repetition-suppression paradigm (Rossion & Boremanse, 2011) to measure rapidly and objectively the sensitivity to symbolic numerical stimuli of 6-to-12-y.o. children (n=20) and adults (n=11). Participants were presented four sequences: two of AN and two of AN-like sham stimuli. Half of the sequences consisted of different stimuli (“10”, “18”, “12”,...), the other half of same stimuli (“10”) presented repeatedly. Stimuli appeared at 3.5 items/second (fundamental frequency=3.5 Hz), for 60 seconds.
We observed a large increase of the EEG response at 3.5 Hz (a steady-state visual-evoked potential; Regan, 1966) over parieto-occipital electrodes. This response was larger during different than same sequences, especially when participants saw real (vs. sham) AN. The amplitude of this specific response to numbers increased with children’s age. Moreover its location changed from posterior occipital electrodes in childhood to more lateral parietal electrodes in adulthood. These results indicate that FPVS of AN is a promising tool to study the sensitivity to numerical magnitude in children and adults.