When asked to compare two stimuli, participants are on average faster to respond Same than Different, an effect coined the fast-same. The dual-process theory argues that information about similarity is processed in priority over any other type of information, causing the fast-same effect. We tested this serial architecture of cognitive processes using a double factorial paradigm, suitable for a Systems Factorial Technology (SFT) analysis. Twenty participants completed a task in which they compared two letters, which were varied on two dimensions: the similarity and the clarity of the letters. Their task was to indicate if the second letter was the Same as the second letter (ranging from identical and clear to similar and slightly blurry) or if it was Different (if the stimuli were either dissimilar or very blurry). The SFT results show that most participants processed the information in serial, but in a mixed order. In other words, for some trials, participants processed similarity first, and for some other trials, they processed clarity first. This implies that participant indeed processed information in serial in the comparison task, but that it does not cause the fast-same effect.

当被要求比较两个刺激时，参与者平均响应“相同”比“不同”更快，这种效果造就了“快速相同”。双重过程理论认为，关于相似性的信息要比任何其他类型的信息优先处理，从而导致快速相同的效果。我们使用适用于系统阶乘技术（SFT）分析的双阶乘范式测试了这种认知过程的串行体系结构。二十名参与者完成了一项任务，他们比较了两个字母，它们在两个维度上有所不同：字母的相似性和清晰度。他们的任务是指出第二个字母是否相同作为第二个字母（范围从相同且清晰到相似且略有模糊）或是否不同（如果刺激不相同或非常模糊）。SFT结果显示，大多数参与者按顺序但混合顺序处理了信息。换句话说，对于某些试验，参与者首先处理相似性，而对于其他一些试验，他们首先处理清晰度。这意味着参与者确实在比较任务中按顺序处理了信息，但不会引起快速相同的效果。