The number decision task: Investigation of the representation of multi-digit numbers

Different theories try to account for the representation and storage of numbers with the common assumption that numbers are transformed from their symbolic format to an analogical quantity representation on the so-called mental number line (MNL;). On the MNL, numbers are represented in a continuous and quantity-based analogical format and are organized by their numerical proximity. Thus, small numbers are located on the left-hand side and large numbers are located on the right, at least in cultures with a reading direction from left to right (e.g., Moeller et al. 2009a, 2011). Although numbers are represented by their numerical proximity, there is increasing fuzziness in the mental representation for larger numbers resulting in less precise processing of larger numbers (Dehaene and Mehler 1992, Dehaene 2001). However, theories differ with regard to the number of MNLs. The holistic model assumes that numbers are represented as a “whole“ on one single MNL (e.g., Dehaene et al. 1990, Brysbaert 1995). According to decompositional models (Nuerk et al. 2001, Verguts and Fias 2004, Ratinckx et al. 2005, Verguts and