The Spatial-Numerical Association of Response Codes (SNARC) effect refers to the fact that smaller numbers receive faster responses with the left hand, and larger numbers with the right hand (Dehaene et al., 1993). This robust finding implies that numbers are associated with space, being represented on a mental number line that progresses from left to right. The SNARC effect is held to depend on relative number magnitude, with the mental number line dynamically adjusting to the numerical range used in a given context. This characterisation is based on significant effects of relative number magnitude, with no significant influence of absolute number magnitude. However, a failure to reject the null hypothesis is not firm evidence for the absence of an effect. In this Registered Report, Roth and colleagues (2024) report two large-sample online experiments, with a Bayesian statistical approach to confirm—or refute—a role for absolute number magnitude in modulating the classic SNARC effect (smallest effect size of interest, d = 0.15).

 

Experiment 1 closely followed Dehaene’s (1993) original methods, and found strong evidence for an influence of relative magnitude, and moderate-to-strong evidence against an influence of absolute magnitude. Experiment 2 was designed to exclude some potential confounds in the original method, and this second experiment found strong evidence for both relative and absolute magnitude effects, of comparable effect sizes (in the range of d = .24 to .42). This registered study demonstrates that the SNARC effect is not ‘fully flexible’, in the sense of depending only on relative number magnitude; it is also shaped by absolute magnitude.

 

This Stage 2 manuscript was evaluated by the recommender and one external reviewer. Following appropriate minor revisions, the recommender judged that the manuscript met the Stage 2 criteria for recommendation.

 

URL to the preregistered Stage 1 protocol: https://osf.io/ae2c8
 
Level of bias control achieved: Level 6. No part of the data or evidence that was used to answer the research question was generated until after IPA.
 
List of eligible PCI RR-friendly journals:
 

• Advances in Cognitive Psychology
• Collabra: Psychology
• Experimental Psychology
• Journal of Cognition
• Peer Community Journal
• PeerJ
• Psychology of Consciousness: Theory, Research, and Practice
• Royal Society Open Science
• Studia Psychologica
• Swiss Psychology Open

 
References

 

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

 

2. Roth, L., Caffier, J., Reips, U.-D., Nuerk, H.-C., Overlander, A. T. & Cipora, K. (2023). One and only SNARC? Spatial-Numerical Associations are not fully flexible and depend on both relative and absolute magnitude [Stage 2]. Acceptance of Version 3 by Peer Community in Registered Reports. https://osf.io/epnd4