Language effects in magnitude comparison: Small, but not irrelevant q Hans-Christoph Nuerk a, * , Ulrich Weger b , Klaus Willmes a, * a Department of Neurology, Section Neuropsychology, University Hospital of the RWTH Aachen, D-52057 Aachen, Germany b Department of Psychology, State University of New York at Binghamton, USA Accepted 22 June 2004 Available online 10 August 2004 Abstract It is assumed that number magnitude comparison is performed by assessing magnitude representation on a single analog mental number line. However, we have observed a unit–decade–compatibility effect in German which is inconsistent with this assumption (Nuerk, Weger, & Willmes, 2001). Incompatible magnitude comparisons in which decade and unit comparisons lead to different responses (e.g., 37_52 for which 3 < 5, but 7 > 2) are slower and less accurately responded to than compatible trials in which decade and unit comparisons lead to the same response (e.g., 42_57, for which 4 < 5 and 2 < 7). As overall distance was held constant, a single holistic magnitude representation could not account for this compatibility effect. However, because of the inversion property of the corresponding German two-digit number words (‘‘einundzwanzig’’ <one-and-twenty>), the language-generality of the effect is questionable. We have therefore examined the compatibility effect with native English speakers. We were able to replicate the com- patibility effect using Arabic notation. Thus, the compatibility effect is not language-specific. However, in cross-linguistic analyses language-specific modulations were observed not only for number words but also for Arabic numbers. The constraints imposed on current models by the verbal mediation of Arabic number comparison are discussed. Ó 2004 Elsevier Inc. All rights reserved. Keywords: Mental number line; Number comparison; Distance effect; Language specificity; Abstract semantic representation 1. Introduction 1.1. Introduction: Magnitude representation and the unit–decade–compatibility effect Virtually every model of number processing assumes some sort of magnitude representation (Campbell, 1994; Dehaene, 1992; Dehaene & Cohen, 1995; McCloskey, 1992; Noel & Seron, 1993). However, the nature of this magnitude representation remains controversial. Deh- aene et al.Õs suggested the metaphor of a mental number line (Dehaene, 1989; Dehaene, Bossini, & Giraux, 1993; Dehaene, Dupoux, & Mehler, 1990; see Moyer & Lan- dauer, 1967; Restle, 1970, for early suggestions) which is thought to be logarithmically compressed. Logarith- mic compression means that the distance between two numbers corresponds to their logarithmic value rather than their linear numerical value (see also Brysbaert, 1995; Dehaene, 2001). Thus, the distance between the numbers 10 and 20 (10 1 and 2 · 10 1 ) on this logarithmi- cally compressed number line would be the same as the distance between the numbers 100 and 200 (10 2 and 2 · 10 2 ). In contrast to the holistic view, McCloskey 0093-934X/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.bandl.2004.06.107 q This research was supported by a grant of the Interdisciplinary Group for Clinical Research—CNS of the RWTH Aachen and a grant by the DFG (German Research Society, KFO 112-TP2) to Klaus Willmes supporting Hans-Christoph Nuerk. We are grateful to Stuart Fellows for his help with checking the English grammar and style of the paper. * Corresponding authors. Fax : +49-241-80-82-598. E-mail addresses: hcnuerk@ukaachen.de (H.-C. Nuerk), willmes@ neuropsych.rwth-aachen.de (K. Willmes). www.elsevier.com/locate/b&l Brain and Language 92 (2005) 262–277