A left-to-right bias in number-space mapping across ages and cultures

Abstract Number and space are inherently related. Previous research has provided evidence that numbers are aligned to a so-called “mental number line”, which is malleable and affected by cultural factors mostly linked to literacy-related habits. However, preverbal humans and non-human animals also m...

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Main Authors: Elena Eccher, Mathilde Josserand, Serge Caparos, Esther Boissin, Marco Buiatti, Manuela Piazza, Giorgio Vallortigara
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-024-55685-x
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author Elena Eccher
Mathilde Josserand
Serge Caparos
Esther Boissin
Marco Buiatti
Manuela Piazza
Giorgio Vallortigara
author_facet Elena Eccher
Mathilde Josserand
Serge Caparos
Esther Boissin
Marco Buiatti
Manuela Piazza
Giorgio Vallortigara
author_sort Elena Eccher
collection DOAJ
description Abstract Number and space are inherently related. Previous research has provided evidence that numbers are aligned to a so-called “mental number line”, which is malleable and affected by cultural factors mostly linked to literacy-related habits. However, preverbal humans and non-human animals also map numerosities into space, in a consistent left-to-right direction. These contrasting findings raise the question of whether Spatial Numerical Associations (SNA) are culturally or biologically determined. Here, we investigated Italian adults, Italian preschoolers, and Himba adults (an indigenous population with an oral cultural system) to examine whether cultural influences are necessary for SNA to emerge. We found that, when explicitly asked to order numerosities, only Italian adults showed a consistent left-to-right preference, while preschoolers and Himba adults did not have a consistent preference for one direction or the other. On the other hand, in a numerosity comparison task, all groups performed better when small numerosities were presented in the left hemispace. These results suggest that humans may display two forms of SNAs, one that emerges mostly in implicit tasks and is biologically determined, and one that emerges in explicit ordering tasks and is determined by cultural habits.
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issn 2041-1723
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spelling doaj-art-921a13d49e014622b4e51cf38d22fd322025-01-12T12:30:14ZengNature PortfolioNature Communications2041-17232025-01-0116111110.1038/s41467-024-55685-xA left-to-right bias in number-space mapping across ages and culturesElena Eccher0Mathilde Josserand1Serge Caparos2Esther Boissin3Marco Buiatti4Manuela Piazza5Giorgio Vallortigara6Center for Mind/Brain Science, University of TrentoCenter for Mind/Brain Science, University of TrentoLaboratoire DysCo, Université Paris 8LaPsyDé, Université Paris CitéCenter for Mind/Brain Science, University of TrentoCenter for Mind/Brain Science, University of TrentoCenter for Mind/Brain Science, University of TrentoAbstract Number and space are inherently related. Previous research has provided evidence that numbers are aligned to a so-called “mental number line”, which is malleable and affected by cultural factors mostly linked to literacy-related habits. However, preverbal humans and non-human animals also map numerosities into space, in a consistent left-to-right direction. These contrasting findings raise the question of whether Spatial Numerical Associations (SNA) are culturally or biologically determined. Here, we investigated Italian adults, Italian preschoolers, and Himba adults (an indigenous population with an oral cultural system) to examine whether cultural influences are necessary for SNA to emerge. We found that, when explicitly asked to order numerosities, only Italian adults showed a consistent left-to-right preference, while preschoolers and Himba adults did not have a consistent preference for one direction or the other. On the other hand, in a numerosity comparison task, all groups performed better when small numerosities were presented in the left hemispace. These results suggest that humans may display two forms of SNAs, one that emerges mostly in implicit tasks and is biologically determined, and one that emerges in explicit ordering tasks and is determined by cultural habits.https://doi.org/10.1038/s41467-024-55685-x
spellingShingle Elena Eccher
Mathilde Josserand
Serge Caparos
Esther Boissin
Marco Buiatti
Manuela Piazza
Giorgio Vallortigara
A left-to-right bias in number-space mapping across ages and cultures
Nature Communications
title A left-to-right bias in number-space mapping across ages and cultures
title_full A left-to-right bias in number-space mapping across ages and cultures
title_fullStr A left-to-right bias in number-space mapping across ages and cultures
title_full_unstemmed A left-to-right bias in number-space mapping across ages and cultures
title_short A left-to-right bias in number-space mapping across ages and cultures
title_sort left to right bias in number space mapping across ages and cultures
url https://doi.org/10.1038/s41467-024-55685-x
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