Attention allows the SNARC effect to operate on multiple number lines.

Area of Science:

• Cognitive Psychology
• Numerical Cognition
• Spatial Representation

Background:

• Investigating the mental representation of numbers is crucial for understanding numerical cognition.
• Previous research suggests numbers are often mapped onto spatial dimensions, but the simultaneous activation of multiple spatial representations is less understood.

Purpose of the Study:

• To determine if individuals can activate a single spatial number line or multiple number lines concurrently.
• To explore how attention to different numerical attributes (units vs. decades) influences spatial number line activation.

Main Methods:

• Participants performed unit magnitude comparison and parity judgment tasks on two-digit numbers.
• A secondary task was introduced, varying in its relevance to number decades (Experiment 1: magnitude comparison; Experiment 2: color judgment).
• Behavioral data were analyzed to assess the influence of units and decades on spatial associations.

Main Results:

• In Experiment 1, where decades were relevant for the secondary task, both units and decades influenced spatial number associations independently.
• In Experiment 2, where decades were irrelevant, only units showed a spatial association with magnitude.
• This indicates that distinct magnitude attributes can support separate spatial representations.

Conclusions:

• Multiple, distinct spatial number lines (e.g., for units and decades) can be activated simultaneously.
• The ability to activate multiple number lines depends on attentional focus on separate magnitude attributes.
• This provides evidence for a flexible and multi-component system for representing numerical magnitude.