It has been reported that approximate number sense (ANS) task performance is impaired in individuals with Williams syndrome (WS) and Down syndrome (DS). Research with infants has suggested this impairment is caused by sticky fixation in WS and sustained attention deficits for those with DS. This study examined looking patterns of older children…

Background: Several theorists maintain that exact number abilities rely on language-relevant processes whereas approximate number calls on visuo-spatial skills. We chose two genetic disorders, Williams syndrome and Down's syndrome, which differ in their relative abilities in verbal versus spatial skills, to examine this hypothesis. Five…