(No) small adults: children's processing of carry addition problems.

Analyses of eye-fixation data in adults suggested that the carry effect in addition is determined by the unit digits of the summands. Correspondingly, we recorded children's eye fixation behavior in a choice reaction paradigm. As for adults the carry effect was most pronounced on the unit digits of the summands. However, children's fixation pattern differed reliably from that of adults in other important aspects. While these data suggested common processes in children and adults for performing a carry in mental addition, children's eye fixation data indicated a less flexible processing style primarily based on calculating the correct result.