title: Human infants' preference for left-to-right oriented increasing numerical sequences.
abstract: While associations between number and space, in the form of a spatially oriented numerical representation, have been extensively reported in human adults, the origins of this phenomenon are still poorly understood. The commonly accepted view is that this number-space association is a product of human invention, with accounts proposing that culture, symbolic knowledge, and mathematics education are at the roots of this phenomenon. Here we show that preverbal infants aged 7 months, who lack symbolic knowledge and mathematics education, show a preference for increasing magnitude displayed in a left-to-right spatial orientation. Infants habituated to left-to-right oriented increasing or decreasing numerical sequences showed an overall higher looking time to new left-to-right oriented increasing numerical sequences at test (Experiment 1). This pattern did not hold when infants were presented with the same ordinal numerical information displayed from right to left (Experiment 2). The different pattern of results was congruent with the presence of a malleable, context-dependent baseline preference for increasing, left-to-right oriented, numerosities (Experiment 3). These findings are suggestive of an early predisposition in humans to link numerical order with a left-to-right spatial orientation, which precedes the acquisition of symbolic abilities, mathematics education, and the acquisition of reading and writing skills.
authors.affiliation: Université Paris Descartes, Laboratoire Psychologie de la Perception, CNRS, UMR 8158, Paris, France; Cognitive NeuroImaging Unit, NeuroSpin, INSERM, U992, Saclay, France.
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: de Hevia
authors.affiliation: Universita' degli Studi di Milano-Bicocca, Department of Psychology, Milano, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Girelli
authors.affiliation: Universita' degli Studi di Milano-Bicocca, Department of Psychology, Milano, Italy.
authors.forename: Margaret
authors.initials: M
authors.lastname: Addabbo
authors.affiliation: Universita' degli Studi di Milano-Bicocca, Department of Psychology, Milano, Italy.
authors.forename: Viola
authors.initials: V
authors.lastname: Macchi Cassia
mesh_terms: D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007223:Infant; D007802:Language; D008297:Male; D008433:Mathematics / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D013028:Space Perception / Q000502:physiology*