Ishihara Masami, Jacquin-Courtois Sophie, Flory Vasantha, Salemme Romeo, Imanaka Kuniyasu, Rossetti Yves
Espace et Action, UMR-S 534 INSERM-UCBL, Institut National de la Santé Et de la Recherche Médicale, 16 Avenue du Doyen Lépine, 69676 Bron, France.
Neuropsychologia. 2006;44(7):1009-16. doi: 10.1016/j.neuropsychologia.2005.11.008. Epub 2006 Jan 10.
The existence of a spatial component in the representation of number magnitude has been repeatedly supported by the demonstration that the left hand responds faster to smaller numbers, whereas the right hand responds faster to larger numbers. These results support the view that the 'mental number line' is oriented such that smaller numbers are associated with the left side of space while larger numbers are associated with the right side. We investigated whether the link between spatial and number processing arises from a continuous or categorical mapping between space and number representations. The investigation was designed to study all aspects of the motor act, including both planning and execution phases. For this purpose we measured reaction times (RTs), movement times (MTs), spatial accuracy, and endpoint pressure of manual aiming, while subjects reached with the right hand towards the location of a visual digit target. Five different digits were equiprobably presented at five positions along the horizontal axis. A GO/NO-GO choice task paradigm was used to ensure that digit parity (i.e., odd/even) was being processed. Analyses of MT, accuracy, and pressure data showed no digit effects. However, two number-related effects were observed on RTs. First, shorter RTs were obtained for smaller digits independent of target location, despite the use of the right hand. Second, an interaction was observed between target location and number magnitude whereby relative RTs were shortest when there was a congruity between target magnitude and location. These results imply that motor preparation is contaminated both by the direct activation of number magnitude and by the congruity between the spatial location of a target number and its magnitude. We conclude that continuous mapping intervenes between mental number representation and physical space.
数字大小表征中空间成分的存在已多次得到证实，即左手对较小数字的反应更快，而右手对较大数字的反应更快。这些结果支持了这样一种观点，即“心理数字线”的方向是较小数字与空间左侧相关联，而较大数字与空间右侧相关联。我们研究了空间与数字处理之间的联系是源于空间与数字表征之间的连续映射还是分类映射。该研究旨在考察运动行为的各个方面，包括计划和执行阶段。为此，我们测量了反应时间（RTs）、运动时间（MTs）、空间准确性以及手动瞄准的终点压力，同时让受试者用右手伸向视觉数字目标的位置。五个不同的数字以等概率出现在水平轴上的五个位置。采用了“是/否”选择任务范式来确保对数字奇偶性（即奇数/偶数）进行处理。对MT、准确性和压力数据的分析未显示数字效应。然而，在RTs上观察到了两个与数字相关的效应。首先，无论使用右手与否，较小数字的RTs更短，且与目标位置无关。其次，观察到目标位置与数字大小之间存在交互作用，即当目标大小与位置一致时，相对RTs最短。这些结果表明，运动准备既受到数字大小直接激活的影响，也受到目标数字空间位置与其大小一致性的影响。我们得出结论，连续映射介于心理数字表征和物理空间之间。
