Mirror numbers activate quantity representations, but show no SNARC effect: A working memory explanation.

The Spatial-Numerical Association of Response Code (SNARC) effect refers to the finding that people respond to small numbers faster with the left hand and to large numbers faster with the right hand. This effect is often explained by hypothesizing that the mental representation of quantities has a spatial component: left to right in ascending order (Mental Number Line). Here we assess the relation between quantity and spatial representation by investigating mirror numbers. Although mirror numbers denote quantity, they are not generally encountered in a left-to-right spatial organization. In Experiments 1 and 2, we assessed whether numerical distance and SNARC effects were present for both mirror and normal numbers when participants were required to process semantic information in a magnitude classification task. In Experiment 3, we assessed whether the SNARC effect was present for both mirror and normal numbers when participants were not required to process semantic information in a mirror judgment task. Results show that participants access the quantity of both normal and mirror numbers, but only normal numbers are spatially organized from left to right. In addition, we show that the physical similarity between numbers successfully predicted the performance of participants. We concluded that the Working Memory account of the SNARC effect best explains our data. (PsycInfo Database Record (c) 2023 APA, all rights reserved).