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Exp Brain Res (2012) 218:2739 DOI 10.1007/s00221-012-2998-7
RESEARCH ARTICLE
Number representation is inuenced by numerical processing level: an ERP study
Junying Liang Jun Yin Tong Chen
Hui Chen Xiaowei Ding Mowei Shen
Received: 4 May 2011 / Accepted: 1 January 2012 / Published online: 18 January 2012 Springer-Verlag 2012
Abstract The same numerical magnitude can be manifested in different physical notations. However, how the numbers with distinct notations are mentally represented is still unclear. Here, we hypothesized that how the number is mentally represented is inuenced by the numerical processing level of the tasks. If the task only needed a low-level processing, the representation would be dependent on the surface forms of the numbers, exhibiting a numerical notation-dependent effect. By contrast, if the task required a deeper magnitude processing, the processing would utilize an abstract numerical format whose effects are notation independent. To test this hypothesis, we manipulated the notation type and the numerical processing level of the tasks. An ERP component N270 was taken to index the mismatch between the internal representation and the probed number. The results showed that N270 was enhanced when the magnitude was mismatched between two numbers. More importantly, under the task requiring a low-level processing (e.g., magnitude comparison), compared with the same notations, the latency of N270 difference wave was delayed by different notations, exhibiting a notation-dependent effect. However, in the task involving a deeper processing (e.g., magnitude addition), the N270 latencies were earlier for probes having distinct notations (Mandarin or Arabic number) than for probes having the same notations as in the addition
operation (Mahjong). Moreover, no difference was found on N270 latencies between the two distinct notations but with similar degree of familiarity. Taken together, these results support our hypothesis that the numerical processing level affects the number representation.
Keywords Number representation Notation Processing level N270
Introduction
Numbers play an important role in human beings life (Rips et al. 2008) and can be conveyed by different notations such as 4 (Arabic numeral), IV (Roman numeral), (Mandarin numeral), and four (English numeral) (Cohen Kadosh and Walsh 2009). One key question of interest is whether these physically distinct forms of numbers are represented in a common abstract form or non-abstract forms1 (e.g., Blankenberger and Vorberg 1997; Eger et al....