Conceptual Size in Developmental Dyscalculia and Dyslexia Yarden Gliksman and Avishai Henik Ben-Gurion University of the Negev Objective: People suffering from developmental dyscalculia (DD) are known to have impairment in numerical abilities and have been found to have weaker processing of countable magnitudes. However, not much research was done on their abilities to process noncountable magnitudes. An example of noncountable magnitude is conceptual size (e.g., mouse is small and elephant is big). Recently, we found that adults process conceptual size automatically. The current study examined automatic processing of conceptual size in students with DD and developmental dyslexia. Method: Conceptual and physical sizes were manipulated orthogonally to create congruent (e.g., a physically small apple compared to a physically large violin) and incongruent (e.g., a physically large apple compared to a physically small violin) conditions. Participants were presented with 2 objects and had to choose the larger one. Each trial began with an instruction to respond to the physical or to the conceptual dimension. Results: Control and the dyslexic groups presented automatic processing of both conceptual and physical sizes. The dyscal- culic group presented automatic processing of physical size but not automaticity of processing conceptual size. Conclusion: Our results fit with previous findings of weaker magnitude representation in those with DD, specifically regarding noncountable magnitudes, and support theories of a shared neurocognitive substrate for different types of magnitudes. General Scientific Summary What is larger, an elephant or a mouse? One can answer this question without seeing these objects since we have a representation of them in our mind. This mental representation is named conceptual size. Recently, we showed that conceptual size is processed automatically. In this research, we explore whether populations with specific learning disabilities (in math or in reading) process conceptual size automatically, and look for the connection between size processing and specific learning disabilities. Keywords: conceptual size, developmental dyscalculia, developmental dyslexia, congruity, objects perception Supplemental materials: http://dx.doi.org/10.1037/neu0000432.supp Considerable research in the field of numerical cognition refers to magnitude comparisons. While many studies investigate count- able comparisons, mostly presented as symbolic and nonsymbolic numerical stimuli, a limited amount of research refers to noncount- able magnitudes. This article examines the automatic processing of conceptual size, a noncountable feature, in students diag- nosed with arithmetic disability. Our data provide evidence that basic processing of noncountable sizes might be deficient in this population. Traditionally, research in the area of numerical cognition held a widely accepted view of the existence of a domain-specific system, which enables perceiving and manipulating discrete quantities (e.g., enumeration of dots; Dehaene, 1997; Dehaene & Cohen, 1995). Moreover, a deficiency in this domain-specific ability is thought to be the basis for arithmetic disability (Butterworth, 2010). In contrast, recent discussions have emphasized the impor- tance of noncountable dimensions in quantities processing, and suggested that a framework in which different types of magni- tudes, both countable and noncountable, are connected to each other and share the same core system of processing (Cantlon, Platt, & Brannon, 2009; Gallistel & Gelman, 2000; Henik, Gliksman, Kallai, & Leibovich, 2017; Henik, Leibovich, Naparstek, Diesen- druck, & Rubinsten, 2012; Leibovich, Katzin, Harel, & Henik, 2016; Leibovich, Katzin, Salti, & Henik, in press; Lourenco, 2016; Walsh, 2003). Moreover, it was claimed that processing of non- countable magnitudes is more basic and automatic than the pro- cessing of discrete magnitudes (Gebuis & Reynvoet, 2012; Leibo- vich, Henik, & Salti, 2015; Zimmermann & Fink, 2016). Nevertheless, not much research has examined the processing of Yarden Gliksman and Avishai Henik, Department of Psychology and the Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev. This work was supported by the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP7/2007– 2013)/ERC Grant Agreement 295644. Correspondence concerning this article should be addressed to Yarden Gliksman, Department of Psychology, Ben-Gurion University of the Ne- gev, P.O Box 653, Beer-Sheva 84105 Israel. E-mail: yarden.gliksman@ gmail.com This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Neuropsychology © 2018 American Psychological Association 2018, Vol. 32, No. 2, 190 –198 0894-4105/18/$12.00 http://dx.doi.org/10.1037/neu0000432 190