Models of numerical cognition consider a visuo-spatial representation to be at the core of numerical processing, the ‘mental number line’. Two main interference effects between number and space have been described: the SNARC effect reflects a small number/left side and large number/right side association (number-location mapping); the size-congruity effect (SCE) reflects a small number/small size and large number/large size association (number-size mapping). Critically, a thorough investigation on the representational source for these two number-space mappings is lacking, leaving open the question of whether the same representation underlies both phenomena. Here, we build on a recent study (Viarouge and de Hevia in Front Hum Neurosci 15:750964, 2021) in order to address this question in three experiments, by systematically manipulating the presence of the two conditions that might elicit an interaction between SNARC and SCE: (i) an implicit task whereby numerical and spatial information are task-irrelevant, (ii) a design in which the number-space congruency relative to both mappings vary at the same level -either both within or between blocks. Experiment 1 replicated the interaction between the two mappings when both factors were present. Experiments 2 and 3 dissociated the two factors by varying the two mappings at the same level but using an explicit comparison task (Experiment 2), or by using an implicit task but with mappings varying at different levels (Experiment 3). We found that both factors, either in combination or used in isolation, drive the interaction between the two number-space mappings. These findings are discussed in terms of the weight given to each mapping, suggesting that a single representation encompassing both number-space mappings is therefore activated whenever both mappings are given equal weight through task requirements.

数值认知模型认为视觉空间表示是数值处理的核心，即“心理数轴”。描述了数字与空间之间的两个主要干扰效应：SNARC效应反映了小数字/左侧和大数字/右侧关联（数字-位置映射）；尺寸一致性效应（SCE）反映了小数量/小尺寸和大数量/大尺寸关联（数量-尺寸映射）。至关重要的是，缺乏对这两种数字空间映射的表征来源的彻底调查，从而留下了相同表征是否是这两种现象背后的问题。在这里，我们以最近的一项研究（Viarouge 和 de Hevia in Front Hum Neurosci 15:750964, 2021）为基础，通过三个实验系统地操纵可能引发 SNARC 和 SNARC 之间相互作用的两个条件的存在来解决这个问题。 SCE：（i）一种隐式任务，其中数字和空间信息与任务无关，（ii）一种设计，其中相对于两个映射的数字空间一致性在同一级别上变化 - 无论是在块内还是在块之间。实验 1 复制了两个因素都存在时两个映射之间的相互作用。实验 2 和 3 通过在同一级别改变两个映射但使用显式比较任务（实验 2），或使用隐式任务但在不同级别改变映射（实验 3）来分离这两个因素。我们发现，这两个因素，无论是组合使用还是单独使用，都会驱动两个数字空间映射之间的相互作用。这些发现是根据赋予每个映射的权重进行讨论的，这表明只要通过任务要求为两个映射赋予相同的权重，就会激活包含两个数字空间映射的单个表示。