The Spatial-Numerical Association of Response Codes (SNARC) effect denotes faster responses to small/large magnitude numbers on the left/right side, respectively (Dehaene et al., 1993). It is observed both in the magnitude classification task (MC), where participants decide whether numbers from 1 to 9 (excluding 5) are smaller or larger than 5, and in the parity judgment task (PJ), where participants decide whether these numbers are odd or even. While number magnitude is task- relevant in MC, it is task-irrelevant in PJ. At the behavioral level, the SNARC effect is categorical (i.e., same left-hand advantage between 1 and 4, and same right-hand advantage between 6 and 9) in MC, but continuous (i.e., increasing right-hand advantage with increasing number magnitude) in PJ. Strikingly, no matter the task, the standard analysis assumes the SNARC effect to be continuous. Only few studies thoroughly investigated similarities and differences between MC-SNARC and PJ-SNARC, and they often lack statistical power. In this registered report, we therefore propose an extensive online study to investigate thoroughly the shape of the MC-SNARC and the PJ-SNARC in a within-subject design and explore other potential differences between the two tasks. Moreover, we will investigate the correlation of the MC-SNARC and the PJ-SNARC. Our main research question is whether we can talk about the SNARC effect, or whether several SNARC effects exist.

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References

Dehaene, S., Bossini, S., & Giraux, P. (1993). The mental representation of parity and number magnitude. Journal of Experimental Psychology: General, 122(3), 371–396. https://doi.org/10.1037/0096-3445.122.3.371