The effect of SNARC compatibility on perceptual accuracy: evidence from object substitution masking

If given a relatively small number and asked to make a speeded parity judgment using the left and right responses, people typically respond faster with their left response. Conversely, if given a relatively large number, people usually respond faster with their right response. This finding, however, has primarily been shown using speeded tasks with response time as the primary measure. Here, we report an experiment testing if this remains to be the case in a non-speeded target identification. Using an object-substitution masking paradigm with no emphasis on response speed, number magnitude compatibility with the response hand influenced the accuracy of parity judgments. Given the non-speeded nature of the task, accuracy changes indicate that compatibility affects perception, rather than just response selection. This is explained using a common coding, feature integration approach in which stimuli and responses are represented in a common code and bidirectionally influence each other.