Notation-dependent processing of numerical magnitude: Electrophysiological evidence from Chinese numerals

To investigate whether the semantic processing of numbers is notation-dependent or notation-independent, three notation stimuli—Arabic digits, Chinese numerals written in simple form (Ch-S), and Chinese numerals written in complex form (Ch-C)—were presented to participants. The participants were asked to judge which target numeral (numerical values 1-4 and 6-9) was “smaller or larger than 5” while event-related potentials (ERPs) were recorded. Electrophysiological results revealed that the voltage activity associated with numerical semantic processing was largest across temporo-occipital-parietal electrode sites, regardless of input formats. However, the time windows for the semantic processing of numerals did not overlap across notations. Furthermore, the main effects of notation and notation/distance interaction were still observed at the stage of numerical magnitude processing, suggesting that notation might affect the semantic processing of numbers. In addition, a right-lateralized N1 for both Arabic digits and Ch-C numbers, and a bilateral N1 for Ch-S numbers, were observed; these data imply that number processing in Chinese speakers may be different from that in Western speakers.