Department of Psychology, Southwest University, Chongqing, China.
PLoS One. 2013 Jul 24;8(7):e69487. doi: 10.1371/journal.pone.0069487. Print 2013.
This study explored event-related potential (ERP) correlates of common fractions (1/5) and decimal fractions (0.2). Thirteen subjects performed a numerical magnitude matching task under two conditions. In the common fraction condition, a nonsymbolic fraction was asked to be judged whether its magnitude matched the magnitude of a common fraction; in the decimal fraction condition, a nonsymbolic fraction was asked to be matched with a decimal fraction. Behavioral results showed significant main effects of condition and numerical distance, but no significant interaction of condition and numerical distance. Electrophysiological data showed that when nonsymbolic fractions were compared to common fractions, they displayed larger N1 and P3 amplitudes than when they were compared to decimal fractions. This finding suggested that the visual identification for nonsymbolic fractions was different under the two conditions, which was not due to perceptual differences but to task demands. For symbolic fractions, the condition effect was observed in the N1 and P3 components, revealing stimulus-specific visual identification processing. The effect of numerical distance as an index of numerical magnitude representation was observed in the P2, N3 and P3 components under the two conditions. However, the topography of the distance effect was different under the two conditions, suggesting stimulus specific semantic processing of common fractions and decimal fractions.
本研究探讨了常见分数（1/5）和小数分数（0.2）的事件相关电位（ERP）相关性。13 名受试者在两种条件下执行数值大小匹配任务。在常见分数条件下，要求非符号分数判断其大小是否与常见分数的大小匹配；在小数分数条件下，要求非符号分数与小数分数匹配。行为结果显示条件和数值距离有显著的主效应，但条件和数值距离没有显著的交互作用。电生理数据显示，当非符号分数与常见分数进行比较时，它们的 N1 和 P3 振幅比与小数分数进行比较时更大。这一发现表明，在两种条件下，非符号分数的视觉识别不同，这不是由于感知差异，而是由于任务要求。对于符号分数，在 N1 和 P3 成分中观察到了条件效应，这表明存在刺激特异性的视觉识别处理。在两种条件下，P2、N3 和 P3 成分中都观察到了数值距离作为数值大小表示的指标的效应。然而，在两种条件下，距离效应的地形图不同，这表明对常见分数和小数分数的刺激有特定的语义处理。
