Symbolic versus non-symbolic magnitude estimations among children and adults

The ability of children and adults to generate symbolic and non-symbolic magnitude estimations was examined in the light of their familiarity with numbers. Children (6-year-old kindergartners, 7-year-old first graders, and 9-year-old third graders) and adults made symbolic estimations either by saying number words that matched numbers of dots (i.e., perception task) or by generating numbers of dots that matched given number words (i.e., production task). In the non-symbolic estimation task, participants generated the corresponding numbers of dots they had seen previously (i.e., reproduction task). In line with the bidirectional mapping hypothesis, children and adults made underestimations in the perception task, overestimations in the production task, and intermediate estimations in the reproduction task. However, the performance of kindergartners and first graders showed significant deviations from the predictions of the bidirectional mapping hypothesis. Their performance in the production task lagged significantly behind that in the perception task, implying that these tasks are not mirrored processes among young children. In addition, they made systematic overestimations in the non-symbolic reproduction task, suggesting that biased mapping occurs here as well. The results are discussed with regard to children's familiarity with numbers and potential estimation strategies.