Knowledge Media Research Center, Tuebingen Germany ; Department of Psychology, Eberhard Karls University, Tuebingen Germany.
Knowledge Media Research Center, Tuebingen Germany ; Section Neuropsychology, Department of Neurology, University Hospital, Rheinisch-Westfälische Technische Hochschule Aachen University Germany.
Front Hum Neurosci. 2014 Apr 1;8:172. doi: 10.3389/fnhum.2014.00172. eCollection 2014.
Decimal fractions comply with the base-10 notational system of natural Arabic numbers. Nevertheless, recent research suggested that decimal fractions may be represented differently than natural numbers because two number processing effects (i.e., semantic interference and compatibility effects) differed in their size between decimal fractions and natural numbers. In the present study, we examined whether these differences indeed indicate that decimal fractions are represented differently from natural numbers. Therefore, we provided an alternative explanation for the semantic congruity effect, namely a string length congruity effect. Moreover, we suggest that the smaller compatibility effect for decimal fractions compared to natural numbers was driven by differences in processing strategy (sequential vs. parallel). To evaluate this claim, we manipulated the tenth and hundredth digits in a magnitude comparison task with participants' eye movements recorded, while the unit digits remained identical. In addition, we evaluated whether our empirical findings could be simulated by an extended version of our computational model originally developed to simulate magnitude comparisons of two-digit natural numbers. In the eye-tracking study, we found evidence that participants processed decimal fractions more sequentially than natural numbers because of the identical leading digit. Importantly, our model was able to account for the smaller compatibility effect found for decimal fractions. Moreover, string length congruity was an alternative account for the prolonged reaction times for incongruent decimal pairs. Consequently, we suggest that representations of natural numbers and decimal fractions do not differ.
十进制分数符合自然阿拉伯数字的基数-10 表示系统。然而，最近的研究表明，十进制分数的表示可能与自然数不同，因为两个数字处理效应（即语义干扰和兼容性效应）在十进制分数和自然数之间的大小存在差异。在本研究中，我们检验了这些差异是否确实表明十进制分数的表示与自然数不同。因此，我们为语义一致性效应提供了另一种解释，即字符串长度一致性效应。此外，我们认为与自然数相比，十进制分数的兼容性效应较小是由于处理策略（顺序与并行）的差异所致。为了评估这一说法，我们在一个大数字比较任务中操纵了十分位和百分位，同时记录了参与者的眼动，而单位位保持不变。此外，我们评估了我们的计算模型的扩展版本是否可以模拟我们的经验发现，该模型最初是为模拟两位数自然数的大小比较而开发的。在眼动追踪研究中，我们发现有证据表明，由于相同的前导数字，参与者对十进制分数的处理更具顺序性，而不是自然数字。重要的是，我们的模型能够解释十进制分数的兼容性效应较小的原因。此外，字符串长度一致性是对不一致的十进制分数对的延长反应时间的另一种解释。因此，我们认为自然数和十进制分数的表示没有区别。
