Early rapid naming longitudinally predicts shared variance in reading and arithmetic fluency.

A number of cognitive factors have been suggested to underlie development in reading and arithmetic skills. Although the two domains are strongly linked, only a few studies have investigated the processes that are shared between them during the early school years. Rapid automatized naming (RAN) has been identified as a strong predictor of a common fluency factor in reading and arithmetic. In the current study with 232 Norwegian children, we examined how RAN in preschool and Grade 1 relates to the shared and nonshared variance in arithmetic fluency and reading fluency in Grade 3. Furthermore, we examined whether related processing skills (phoneme awareness, working memory, speed of processing, and symbol knowledge) can account for the relationship between RAN and shared fluency-or if they predict variance that is unique to each domain. Our results show that RAN in both preschool and Grade 1 is a strong predictor of shared variance between reading fluency and arithmetic fluency measured several years later, whereas other predictors mainly relate to the nonshared parts of variance in the fluency outcomes. That is, control variables with the theoretical potential to explain some of RAN's relation to the overlap between reading and arithmetic fluency do not in fact account for this relationship. Our findings provide a starting point for future investigations of the mechanisms of rapid naming.