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Clinical Trial
. 2014 Apr 23;9(4):e95756.
doi: 10.1371/journal.pone.0095756. eCollection 2014.

The cognitive mechanisms of the SNARC effect: an individual differences approach

Arnaud Viarouge  1 , Edward M Hubbard  2 , Bruce D McCandliss  3
Affiliations
Clinical Trial

The cognitive mechanisms of the SNARC effect: an individual differences approach

Arnaud Viarouge et al. PLoS One. .

Abstract

Access to mental representations of smaller vs. larger number symbols is associated with leftward vs. rightward spatial locations, as represented on a number line. The well-replicated SNARC effect (Spatial-Numerical Association of Response Codes) reveals that simple decisions about small numbers are facilitated when stimuli are presented on the left, and large numbers facilitated when on the right. We present novel evidence that the size of the SNARC effect is relatively stable within individuals over time. This enables us to take an individual differences approach to investigate how the SNARC effect is modulated by spatial and numerical cognition. Are number-space associations linked to spatial operations, such that those who have greater facility in spatial computations show the stronger SNARC effects, or are they linked to number semantics, such that those showing stronger influence of magnitude associations on number symbol decisions show stronger SNARC effects? Our results indicate a significant correlation between the SNARC effect and a 2D mental rotation task, suggesting that spatial operations are at play in the expression of this effect. We also uncover a significant correlation between the SNARC effect and the distance effect, suggesting that the SNARC is also related to access to number semantics. A multiple regression analysis reveals that the relative contributions of spatial cognition and distance effects represent significant, yet distinct, contributions in explaining variation in the size of the SNARC effect from one individual to the next. Overall, these results shed new light on how the spatial-numerical associations of response codes are influenced by both number semantics and spatial operations.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Diagram of the predicted relations.
This graph shows the predicted constructs of the SNARC effect according to the account of the spatial mental number line. The connectors show the tested correlations (non-predicted relations are shown with dashed lines).
Figure 2
Figure 2. Split-half reliability of the SNARC effect.
This graph shows the scatterplot of the correlation between the amplitudes of the SNARC effect computed from two halves of the trials, and the corresponding regression line.
Figure 3
Figure 3. Test-retest reliability of the SNARC effect.
This graph shows the scatterplot of the correlation between the amplitudes of the SNARC effect computed from the two experimental sessions, and the corresponding regression line.
Figure 4
Figure 4. Correlation between the SNARC and the distance effect.
This graph shows the scatterplot of the correlation between the mean amplitudes of the SNARC effect and the amplitude of the distance effect, and the corresponding regression line.
Figure 5
Figure 5. Correlation between the SNARC effect and the 2D Mental Rotation.
This graph shows the scatterplot of the correlation between the mean amplitudes of the SNARC effect and the amplitude of the angle effect observed in the 2D mental rotation task, and the corresponding regression line.
See this image and copyright information in PMC

References

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    1. Hubbard EM, Piazza M, Pinel P, Dehaene S (2005) Interactions between number and space in parietal cortex. Nature Reviews Neuroscience 6(6): 435–448. - PubMed

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