Attention allows the SNARC effect to operate on multiple number lines

Abstract

To investigate whether participants can activate only one spatially oriented number line at a time or multiple number lines simultaneously, they were asked to solve a unit magnitude comparison task (unit smaller/larger than 5) and a parity judgment task (even/odd) on two-digit numbers. In both these primary tasks, decades were irrelevant. After some of the primary task trials (randomly), participants were asked to additionally solve a secondary task based on the previously presented number. In Experiment 1, they had to decide whether the two-digit number presented for the primary task was larger or smaller than 50. Thus, for the secondary task decades were relevant. In contrast, in Experiment 2, the secondary task was a color judgment task, which means decades were irrelevant. In Experiment 1, decades’ and units’ magnitudes influenced the spatial association of numbers separately. In contrast, in Experiment 2, only the units were spatially associated with magnitude. It was concluded that multiple number lines (one for units and one for decades) can be activated if attention is focused on multiple, separate magnitude attributes.

The spatial–numerical association of response codes effect and math skills: why related?

“…Another method of quantifying the SNARC effect involves the variance explained by the regression predictor. This can be important because for some SNARC paradigms (parity judgment), a continuous predictor is the better predictor, while for other paradigms (e.g., magnitude classification), a categorical (contrast‐coded small‐ and large‐magnitude numbers) predictor is better suited to account for the actual data 25 . Importantly, the conclusions of studies we discuss below did not differ depending on which specific method was used to quantify the SNARC effect.…”

Automatic place-value activation in magnitude-irrelevant parity judgement

“…Appendix A; see also Weis, Nuerk, & Lachmann, 2018 for parallel SNARC effects for decades and units of two-digit numbers if both are attended). On the other hand, the MARC effect, i.e., faster left/right responses to odd/even numbers , was absent.…”

The Spatial Numerical Association of Response Codes effect and math skills: why related?

“…Another method of quantifying the SNARC effect involves the variance explained by the regression predictor. This can be important because for some SNARC paradigms (parity judgement) a continuous predictor is the better predictor, while for other paradigms (e.g., magnitude classification) a categorical (contrast coded small and large magnitude numbers) predictor is better suited to account for the actual data 25 . Importantly, the conclusions of studies we discuss below did not differ depending on which specific method was used to quantify the SNARC effect.…”

“…Numerical magnitudes can be semantically processed without the presence of spatial associations 54,55 . It seems that selective attention oriented towards numbers allows / facilitates the process of associating them with space 25 . This observation not only stems from typical SNARC bi-manual setups.…”