Semantic numerical representation in blind subjects: The role of vision in the spatial format of the mental number line

Abstract

Does vision play a role in the elaboration of the semantic representation of small and large numerosities, notably in its spatial format? To investigate this issue, we decided to compare in the auditory modality the performance of congenitally and early blind people with that of a sighted control group, in two number comparison tasks (to 5 and to 55) and in one parity judgement task. Blind and sighted participants presented exactly the same distance and SNARC (Spatial Numerical Association of Response Codes) effects, indicating that they share the same semantic numerical representation. In consequence, our results suggest that the spatial dimension of the numerical representation is not necessarily attributable to the visual modality and that the absence of vision does not preclude the elaboration of this representation for 1-digit (Experiment 1) and 2-digit numerosities (Experiment 2). Moreover, as classical semantic numerical effects were observed in the auditory modality, the postulate of the amodal nature of the mental number line for both small and large magnitudes was reinforced.

Space and time in the sighted and blind

“…Like temporal relationships, numerical relationships are also represented spatially by means of a horizontal Mental Number Line (MNL) where lower numbers are associated with the left side of space and higher numbers with the right side (Dehaene, Bossini & Giraux, 1993). Although a space-number mapping can also be observed in the early blind (Castronovo & Seron, 2007), they use a different FoR to represent numbers compared to sighted or late blind (who lost their sight after age ~3; Crollen, et al 2013). In a space-number congruity task, participants pressed buttons on the left and right side of space to judge number magnitude.…”

Representational Structures of Arithmetical Thinking: Part I

“…Up to now, SNARC effects have been observed in the presentation of Arabic digits, Indo-Arabic numerals ), Chinese numerals (Hung et al 2008), written verbal numerals (Fias et al 1996;Nuerk et al 2005), spoken verbal numerals (Nuerk et al 2005;Castronovo and Seron 2007) and non-symbolic numerals in the form of the arrangement of dots on a die (Nuerk et al 2005) and various, randomly scattered elements on a computer screen (Patro and Haman 2012). Furthermore, analyses of experimental results also show that the strength of the effect under discussion is not dependent upon whether numerals are read or heard (Nuerk et al 2005;Wood et al 2008;.…”

“…In one experiment (Castronovo and Seron 2007), numerals were reproduced from speakers to blind people. Blind participants were asked to judge the parity of heard numerals or, in the second version of the experiment, they had to decide whether a numeral being heard was greater than five.…”

Algebraic Models of Mental Number Axes: Part II

“…One may distinguish the following main categories of evidence: (i) experimental data given in SNARC experiments (in particular, see: Dehaene et al 1993;Zhou et al 2008;Brysbaert 1995;Tlauka 2002;Castronovo and Seron 2007;Patro and Haman 2012) (ii) neurophysiological data concerned with processes of neuronal activations during acts of numerical reference; (iii) experimental data showing distance and size effects, and (iv) observational facts consisting in our peculiar numerical abilities, such as: subitizing small cardinalities, estimating quantificational sizes of numbers and, finally, counting high cardinalities in the case of savant syndrome.…”