Response to Comments on “Number-space mapping in the newborn chick resembles humans’ mental number line”

et al. 2019

Developmental Science

Self Cite

115

Humans represent numbers on a mental number line with smaller numbers on the left and larger numbers on the right side. A left‐to‐right oriented spatial–numerical association, (SNA), has been demonstrated in animals and infants. However, the possibility that SNA is learnt by early exposure to caregivers’ directional biases is still open. We conducted two experiments: in Experiment 1, we tested whether SNA is present at birth and in Experiment 2, we studied whether it depends on the relative rather than the absolute magnitude of numerousness. Fifty‐five‐hour‐old newborns, once habituated to a number (12), spontaneously associated a smaller number (4) with the left and a larger number (36) with the right side (Experiment 1). SNA in neonates is not absolute but relative. The same number (12) was associated with the left side rather than the right side whenever the previously experienced number was larger (36) rather than smaller (4) (Experiment 2). Control on continuous physical variables showed that the effect is specific of discrete magnitudes. These results constitute strong evidence that in our species SNA originates from pre‐linguistic and biological precursors in the brain.

Section: Discussionmentioning

confidence: 99%

A mental number line in human newborns

Giorgio

Lunghi

et al. 2019

Developmental Science

Self Cite

115

“…Caution has been urged, however, when using animal models to understand the origin of the orientation of human MNL (42). Convergent evolution, in which species from diverse evolutionary lineage could independently develop similar features (43), and strong differences in brain organization and lateralization (21, 44) could affect interpretation of comparative evidence (but see 45, 46). Nevertheless, comparative as well as developmental studies have been, so far, unable to unequivocally address the origin of human MNL.…”

Section: Discussionmentioning

confidence: 99%

A mental number line in human newborns

Lunghi

Giorgio

et al. 2017

Preprint

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2 3 In the 19 th century Francis Galton first reported that humans represent numbers on a 4 mental number line with smaller numbers on the left and larger numbers on the right. It has 5 been suggested that this orientation emerges as a result of reading/writing habits for both 6 words or numbers. Recent evidence in animals and infants in the first months of life has 7 challenged the primary role of language in determining the left-to-right direction of spatial-8 numerical association, SNA. However, the possibility that SNA is learnt by early exposure to 9 caregivers' directional biases is still open. Here we show that 55-hour-old newborns, once 10 habituated to a number (i.e., 12), spontaneously associated a smaller number (i.e., 4) with the 11 left side and a larger number (i.e., 36) with the right side of space. Moreover, SNA in neonates 12 was not absolute but relative. The same number (i.e., 12) was associated with the left side 13 whenever the previously experienced number was larger (i.e., 36), but with the right side 14 whenever the number was smaller (i.e., 4). Control on continuous physical variables showed 15 that the effect was specific of discrete magnitudes. Hence, soon after birth humans associate 16 smaller numbers with the left space and larger numbers with the right space. These results 17 constitute strong evidence that in our species SNA originates from pre-linguistic and 18 biologically precursors in the brain.19 20 21 SIGNIFICANCE STATEMENT 22 For human adults, the representation of number and space is profoundly intertwined. 23 Humans represent numbers on a left to right oriented Mental Number Line (MNL), with 24 small numbers located on the left and larger ones on the right. How do these connections 25 3 arise? Do we learn to associate numbers with space throughout cultural learning and social 1 interactions or is this association rooted in the biology of the human brain? We showed that 2 neonates spontaneously associate numbers with space. After being habituated to a certain 3 number, neonates associated a smaller number with the left and a larger number with the 4 right side. This evidence demonstrates that a predisposition to map numbers onto space is 5 rooted in human neural systems.6 7

“…More importantly, in the third condition, there was a negative correlation between overall area and number: the overall area of the 32 elements was smaller than that of the 20 elements (training), and smaller than that of 8 elements. Again, chicks circumnavigate the left panel in the Small Number Test (8vs.8) and the right panel in the Large Number Test (32vs.32), demonstrating that is the number of elements-and not the quantity of area, perimeter, color, light, density-that is associated with space (Rugani, Vallortigara, Priftis, & Regolin, 2015a;2015b). It should also be noted that, besides some critical comments, these results can be explained by the numerical magnitudes of the stimuli and not by aesthetic judgments, nor by biological or behavioral brain asymmetries (Rugani, Vallortigara, Priftis, & Regolin, 2016a;2016b).…”

Section: Number Space Association In Non-human Animalsmentioning

confidence: 98%

Number-space associations without language: Evidence from preverbal human infants and non-human animal species

Hevia

2016

Psychon Bull Rev

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It is well known that humans describe and think of numbers as being represented in a spatial configuration, known as the 'mental number line'. The orientation of this representation appears to depend on the direction of writing and reading habits present in a given culture (e.g., left-to-right oriented in Western cultures), which makes this factor an ideal candidate to account for the origins of the spatial representation of numbers. However, a growing number of studies have demonstrated that non-verbal subjects (preverbal infants and non-human animals) spontaneously associate numbers and space. In this review, we discuss evidence showing that pre-verbal infants and non-human animals associate small numerical magnitudes with short spatial extents and left-sided space, and large numerical magnitudes with long spatial extents and right-sided space. Together this evidence supports the idea that a more biologically oriented view can account for the origins of the 'mental number line'. In this paper, we discuss this alternative view and elaborate on how culture can shape a core, fundamental, number-space association.