Abstract
For small and large numerosities, we evaluated the subitizing capacity, as well as accuracy and precision of visual enumeration across development. We asked children 6 -11 years of age and adults to visually enumerate by "ones" (1-9) or by "tens" (10-90). To analyze whether the ratio differences, 1 to 2 and 1 to 3, is responsible for enumeration, we compared the accuracies for ratios of 10 to 20 and 10 to 30. We found that enumeration functions of "ones" and "tens" have different characteristics, which is consistent with the presence of two number systems. Across all ages we found a subitizing capacity for 1-3 elements, but not for 10-30 elements. This suggests that subitization is limited to small numerosities (<4 elements) and is independent of the relative ratio between quantities. Responses of children were more variable than adult responses. Counting by "ones," children enumerate similarly to adults, with the exception of 6-7 year olds, who underestimated for numerosities greater than 6. Moreover, when counting by "tens," children disproportionately underestimated relative to adults with the degree of underestimation decreasing as a function of age. These data show that while subitization capacity is adult-like in children 6-7 years of age, enumeration accuracy and precision reaches maturity after 11 years of age.
Meeting abstract presented at VSS 2012