It is generally accepted that the mental representation of numerical magnitude consists of a spatial “mental number line” (MNL) with smaller quantities on the left and larger quantities on the right. However, the amount of dissociations between tasks that were believed to tap onto this representational medium is accumulating, questioning the universality of this model. The aim of the present study was to unravel the functional relationship between the different tasks and effects that are typically used as evidence for the MNL. For this purpose, a group of right brain damaged patients (with and without neglect) and healthy controls were subjected to physical line bisection, number interval bisection, parity judgment, and magnitude comparison. Using principal component analysis, different orthogonal components were extracted. We discuss how this component structure captures the dissociations reported in the literature and how it can be considered as a first step toward a new unitary framework for understanding the relation between numbers and space.
Keywords: numbers, space, attention, working memory, SNARC, neuropsychology
Citation: van Dijck J-P, Gevers W, Lafosse C and Fias W (2012) The heterogeneous nature of number–space interactions. Front. Hum. Neurosci. 5:182. doi: 10.3389/fnhum.2011.00182
Received: 13 September 2011; Accepted: 19 December 2011;
Published online: 10 January 2012.
Edited by:Filip Van Opstal, Ghent University, Belgium
Reviewed by:Konstantinos Priftis, University of Padova, Italy
Copyright: © 2012 van Dijck, Gevers, Lafosse and Fias. This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited.
*Correspondence: Jean-Philippe van Dijck, Department of Experimental Psychology, Ghent University, H. Dunantlaan 2, B-9000 Ghent, Belgium. e-mail: firstname.lastname@example.org