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.