Superior numerical abilities following early visual deprivation

Abstract

In numerical cognition vision has been assumed to play a predominant role in the elaboration of the numerical representations and skills. However, this view has been recently challenged by the discovery that people with early visual deprivation not only have a semantic numerical representation that shares the same spatial properties with that in sighted people, but also have better numerical estimation skills. Here, we show that blind people's superior numerical abilities can be found in different numerical contexts, whether they are familiar or more general. In particular, we found that blind participants demonstrated better numerical estimation abilities than sighted participants in both an ecologic footstep and an unfamiliar oral verbal production task. Blind participants also tend to show greater working memory skills compared to sighted participants. These findings support the notion that vision is not necessary in the development of numerical cognition and indicate that early visual deprivation may even lead to a general enhancement in numerical estimation abilities. Moreover, they further suggest that blind people's greater numerical skills might be accounted by enhanced high-level cognitive processes, such as working memory.

Enhanced verbal abilities in the congenitally blind

“…For example, the evidence for a working memory advantage in the blind is primarily from studies of children (Tillman & Bashaw, 1968; Smits & Mommers, 1976; Hull & Mason, 1995; Withagen et al, 2013). However, although studies of adults show no significant differences between the blind and sighted (Castronovo & Delvenne, 2013; Pigeon & Marin-Lamellet, 2015) this was likely due to ceiling effects (and see Swanson & Luxenberg, 2009, for equivocal results in children). Similarly, some studies show that the congenitally blind and the sighted perform equally well on spatial memory tasks (Cornoldi et al, 1991; Ruggiero & Iachini, 2010).…”

Visuo-spatial processes as a domain-general factor impacting numerical development in atypical populations

“…The P300 was described as reflecting higher cognitive processes such as retrieval and maintenance of a representation in working memory. The absence of visual input could therefore lead blind people to process numbers in a more cognitive way, relying much more on verbal working memory than on sensory processes (see Castronovo & Delvenne, 2013;Crollen, Mahe, Collignon, & Seron, 2011;Crollen et al, 2014 for similar conclusions).…”

“…Indeed, it is interesting to note that people with blindness were shown to present similar (Castronovo & Seron, 2007a;Crollen et al, 2013Crollen et al, , 2014 or even better (Castronovo & Delvenne, 2013;Castronovo & Seron, 2007b;Dormal et al, 2016) numerical performances than their sighted peers in a series of numerical tasks. This observation, coupled with the fact that even infants with WS present relative strengths on some numerical tasks (Ansari et al, 2003;O'Hearn et al, 2011), suggest that the numerical system is flexible enough to rely on different kinds of sensory and cognitive strategies to develop.…”

“…• Similar reference frame than the sighted in verbal-spatial tasks (Castronovo & Seron, 2007a) but different frames of reference in viusospatial tasks (Crollen et al, 2013) • Pseudo-neglect in number bisection tasks (Cattaneo et al, 2011;Rinaldi et al, 2015) • ↑ Estimation abilities (Castronovo & Delvenne, 2013;Castronovo & Seron, 2007b;Ferrand et al, 2010) • ↑ Calculation • Similar reference frame than the sighted to represent the mental time line (Bottini et al, 2015) Hemineglect • Defective spatial working memory • Difficulty to shift spatial attention toward the left • Visual and haptic space influenced by number-related attentional shifts (Cattaneo et al, 2012) • Rightward bias in number bisection tasks (Hoeckner et al, 2008;Zorzi et al, 2002Zorzi et al, , 2006 corrected by prism adaptation (Rossetti et al, 2004) and optokinetic stimulation (Priftis et al, 2012) • Impaired performance and enhanced distance effect for smaller magnitudes • ↓ Accuracy in number-to position task • ↓ Accuracy in non-symbolic and symbolic comparison task (Gomez et al, 2015) • No SNARC effect (Bachot et al, 2005; • More outliers responses and no order effect in number bisection task • ↓ Mathematics (Vaivre-Douret et al,…”

“…Individuals with blindness presented similar accuracy levels in all the tasks described above. They perform even better than sighted in various numerosity estimation tasks (Castronovo & Delvenne, 2013;Castronovo & Seron, 2007b;Ferrand, Riggs, & Castronovo, 2010) and in some calculation experiments involving addition and multiplication operations (Dormal, Crollen, Baumans, Lepore, & Collignon, 2016). Vision is therefore not mandatory for the emergence of numerical-spatial interactions, even though visual experience affects the nature of this relation (Crollen & Collignon, 2012).…”