Investigating the Cognitive and Developmental Dynamics of Groupitizing
Starkey, Gillian Sarah
“Groupitizing,” or the ability to quickly enumerate an array of items that is grouped into subitizable subsets, has recently been shown to predict children’s symbolic math skills. It has been proposed that groupitizing involves subitizing the subgroup quantities, and then drawing upon insights into number composition and set combination to access the overall array quantity, thus bypassing serial counting and addition. First, a longitudinal study was conducted to track children’s groupitizing and other enumeration skills across early elementary school. Hierarchical linear models demonstrated that groupitizing fluency improves throughout elementary school, and accounts for significant and unique variance in developing symbolic arithmetic ability. Second, a cross-sectional study tested the proposed model of groupitizing by examining the impact of manipulating the structure of the grouped arrays. Results supported the proposed model of groupitizing, further suggesting that after subgroups are subitized, knowledge of the combinations of sets that comprise numbers provides access to the overall array quantity. Results also highlighted differences in groupitizing fluency and conceptual number knowledge between participants who could and could not subitize four items. Finally, an EEG study was conducted to assess the feasibility of examining children’s subitizing by measuring the N2pc component. This feasibility study was unsuccessful in reliably measuring the N2pc in children, but was helpful in informing future studies of this EEG component in developmental populations. Overall, results indicate that groupitizing reflects conceptual number knowledge that is critical for math development. Improving children’s skills in set combination and number composition should be a focus of math education in early elementary school.