The origins of the numerical distance effect: The same–different task

Abstract

One of the most frequently used markers in research on numerical cognition is the distance effect. Recently, we have suggested that a distance effect can have different origins depending on the experimental task. By dissociating the comparison distance effect from the priming distance effect we revealed the need to study the origin of this effect before drawing any conclusions from it (van Opstal, Gevers, de Moor, & Verguts, 2008). Because a distance effect in a same–different task is also commonly used to study number representations (e.g., Dehaene & Akhavein, 1995), the present study aimed at uncovering the origin of the effect in this task. Computational and empirical results indicate clearly that the distance effect in the same–different task originates from number representations rather than a decision process.