Early visual deprivation does not prevent the emergence of basic numerical abilities in blind children.

Abstract

Studies involving congenitally blind adults demonstrated that visual experience is not a mandatory prerequisite for the emergence of efficient numerical abilities. It remains however unknown whether blind adults developed lifelong strategies to compensate for the absence of foundations vision would provide in infancy. We therefore assessed basic numerical abilities in blind and sighted children of 6 to 13 years old. We also assessed verbal and spatial working memory abilities and their relationship with mental arithmetic in both groups. Blind children showed similar or better numerical abilities as compared to the sighted. Blind children also outperformed their sighted peers in every task assessing verbal working memory and demonstrated a similar spatial span. The correlation between arithmetic and the spatial sketchpad was affected by the group while the correlations between arithmetic and the other two components (the central executive and the phonological loop) were not affected by early visual experience. Our data suggest that early blindness does not impair the development of basic numerical competencies in children but influences the associations between arithmetic and some working memory components.

The embodiment of number knowledge in sensorimotor experience: The facts behind the questions and the questions before us

“…They generally include children or adults with vision loss, due to congenital disorders of the peripheral visual system, in the absence of any other cognitive deficit. Their performance was found equalif not superiorto the performance of sighted people in numerical judgments (Castronovo & Seron, 2007), counting (Crollen et al, 2014), estimation (Castronovo & Delvenne, 2013;Ferrand et al, 2010), working memory (Crollen et al, 2021) or arithmetic (Dormal et al, 2016). In the same time, finger counting was less often observed among blind than sighted children and when they were explicitly asked to rely on finger counting, blind children preferred tapping on the table or touching their fingertips with the other hand.…”

“…Under an embodied view, it is reasonable to assume a progression from overt to covert counting so that children get able to support enumeration through very subtle movements that cannot be easily detected with standard behavioural methods (Wilson, 2002). A longitudinal study from kindergarten might actually reveal that blind children shift more rapidly than sighted to covert counting because of superior working memory capacity (Crollen et al, 2021).…”

Early visual deprivation disrupts the mental representation of numbers in visually impaired children

“…Responses were recorded by the experimenter standing behind the participants' seats and seeing the graduations of the graph paper. As in Crollen et al 38 , performance at the task was measured as Percentage of Absolute Error (i.e., PAE), which corresponds to the absolute value of the Percentage of Error (i.e., PE). The PE for each number was computed: ((participant's number estimation − true number)/line's scale) * 100.…”

“…Finally, most of existing studies investigated numerical performance in visually impaired adults rather than children. To our knowledge, only one study 38 assessed the performance of congenitally blind children in a series of visuospatial numerical tasks (number-to-position, number bisection, counting, and mathematical operations). The authors reported that visual deprivation from birth does not affect numerical performance, which seems to affect the association between arithmetic competence and working memory mechanisms.…”

“…Understanding whether visually impaired individuals may develop numerical impairments according to their visual residuals and when such impairments may manifest during growth would be of fundamental importance for therapeutic purposes, since rehabilitation protocols might be specifically targeted on the perceptual deficits spotted from early infancy. To fill this gap, we investigated how visual deprivation from birth impacts number representation by administering a revised version of the tactile number-to-position task proposed by Crollen et al 38 to low vision and blind children, requiring them to position positive and negative numbers on the horizontal and the sagittal planes. We hypothesize that visually impaired children would show a worsen performance when asked to represent numbers in the sagittal instead of the horizontal plane.…”