Human number understanding is thought to rely on the analogue number system (ANS), working according to Weber's law. We propose an alternative account, suggesting that symbolic mathematical knowledge is based on a discrete semantic system (DSS), a representation that stores values in a semantic network, similar to the mental lexicon or to a conceptual network. Here, focusing on the phenomena of numerical distance and size effects in comparison tasks, first we discuss how a DSS model could explain these numerical effects. Second, we demonstrate that DSS model can give quantitatively as appropriate a description of the effects as the ANS model. Finally, we show that symbolic numerical size effect is mainly influenced by the frequency of the symbols, and not by the ratios of their values. This last result suggests that numerical distance and size effects cannot be caused by the ANS, while the DSS model might be the alternative approach that can explain the frequency-based size effect.Keywords: Numerical cognition; Numerical distance effect; Numerical size effect; Analogue number system; Discrete semantic system 1 An alternative to the analogue number system According to the current models understanding numbers is supported by an evolutionary ancient representation shared by many species (Dehaene, Dehaene-Lambertz, & Cohen, 1998;Gallistel & Gelman, 2000;Hauser & Spelke, 2004), the analogue number system (ANS). One defining feature of the ANS is that it works similarly to some perceptual representations in which the ratio of the stimuli's intensity determines the performance (Weber's law) (Cantlon, Platt, & Brannon, 2009;Moyer & Landauer, 1967;Walsh, 2003). Two critical phenomena supporting the ratio based performance is the distance and the size effects: when two numbers are compared, the smaller the distance between the two values is or the larger the two numbers are, the slower and more error prone the comparison is (Moyer & Landauer, 1967) (Figure 1 and 2). Thus, in the literature, the numerical distance and size effects are considered to be the sign of an analogue noisy numerical processing system working according to Weber's law. The distance and the size effects are observable both in non-symbolic and symbolic number processing, reflecting that the same type of system processes numerical information, independent of the number notations (Dehaene, 1992;Eger, Sterzer, Russ, Giraud, & Kleinschmidt, 2003).However, the distance and size effects in symbolic comparison can also be explained by a different representation. Quite intuitively, one might think that symbolic and abstract mathematical concepts, Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 7 September 2016 doi:10.20944/preprints201609.0025.v1
PREPRINTThe source of the symbolic numerical distance and size effects 2 like numbers could be handled by a discrete semantic system (DSS), similar to conceptual networks or to the mental lexicon, i.e., representations that process symbolic and abstract concepts. In this DSS model, numbers are stor...