Diagnostik und Kognitive Neuropsychologie

Automaticity of the SNARC effect

Apart from processing numbers deliberately when required in a given situation, we often process them automatically. This is reflected by the SNARC (Spatial-Numerical Association of Response Codes; Dehaene et al., 1993) effect, which describes faster responses to smaller/larger numbers with the left/right, respectively. It arises in semantic number-processing tasks both when number magnitude is task-relevant (e.g., magnitude classification task) and task-irrelevant (e.g., parity judgment task). However, findings on the SNARC effect in tasks requiring the processing of non-semantic number features are mixed: It has been observed in orientation judgment tasks, but mostly not in color judgment tasks. Importantly, previous studies were underpowered or did not control for confounding variables.

Our results:

In two highly powered online experiments, we found a small but significant SNARC effect in both nominal color judgment (blue vs. yellow; slope = 1.71) and color intensity judgment (light cyan vs. dark cyan; slope = 1.13) of Arabic digits, which did not differ in size. In contrast, we found no or at most little evidence for the MARC (Linguistic Markedness of Response Codes; Nuerk et al., 2004) effect in color judgment, which describes faster responses to odd/even numbers with the left/right, respectively. Taken together, number magnitude seems to be processed automatically and mentally mapped onto space even if participants respond to physical non-semantic features of presented numbers, whereas the processing of number parity is less automatic.


Categorical Color Judgment (blue vs. yellow)

Color Intensity Judgment (light cyan vs. dark cyan)



Nominal Color Judgment (blue vs. yellow)

Color Intensity Judgment (light cyan vs. dark cyan)



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

Nuerk, H.-C., Iversen, W., & Willmes, K. (2004). Notational modulation of the SNARC and the MARC (linguistic markedness of response codes) effect. The Quarterly Journal of Experimental Psychology. A, Human Experimental Psychology, 57(5), 835–863. https://doi.org/10.1080/02724980343000512