Does the spatial-numerical association of response codes effect depend on digits' relative or absolute magnitude? Evidence from a perceptual orientation judgment task.

Many previous studies have demonstrated the SNARC effect-i.e., participants are faster to respond with their left/right hand to small/large numbers. However, there is a debate on whether it is based on working or long-term memory (i.e., relative or absolute magnitude). Here, we examined the flexibility of the spatial-numerical associations using orientation judgment tasks. Participants were asked to judge the orientation of a rotated frame surrounding an Arabic digit under numerical ranges 1-6, 4-9 (Experiment 1), and 1-9 (Experiment 2). The task difficulty was manipulated by rotating stimuli. We observed a significant SNARC effect for range 1-6 and a reversed SNARC effect for 4-9, regardless of the total numerical range presented in the task. Furthermore, the SNARC effect became more salient with increasing task difficulty. Our results suggest that the SNARC effect is based on the absolute magnitude of digits, supporting the long-term memory explanation.