The numerical distance effect (inverse relationship between numerical distance and reaction time in relative number comparison tasks) has frequently been used to characterize the mental representation of number. The size of the distance effect decreases over developmental time. However, it is unclear whether this reduction simply reflects…

Understanding of the cardinality principle in children with Williams Syndrome (WS) was compared to that of typically developing children. Findings indicated that such understanding was extremely delayed in WS children and only at the level predicted by their visuo-spatial mental age. Findings suggested that visuo-spatial ability played a greater…