An ERP study on multiplication and its relationship to phonological processing in children and adults.

Associations between arithmetic and reading skills suggest that these important abilities may rely, at least in part, on shared neurocognitive processes. It has been argued that retrieval of arithmetic facts may rely on phonological processing; however, very few studies have explored this association using neural indices and whether it manifests similarly in children and adults. Here we examined event related potentials (ERPs) as an indirect neural correlate of arithmetic fact retrieval, and whether variability in ERP modulation is associated with individual differences in phonological processing (verbal working memory, rate of access, and phonological awareness). Arithmetic processing was examined in two samples with different levels of arithmetic expertise: (1) young adults (n = 24; M_age = 21.8 years); and (2) children (n = 25; M_age = 11.2 years). Participants were presented with simple multiplication equations that were correct or incorrect. Significant modulations of the ERPs by correctness were found at posterior electrodes in both samples, however, in different components. In adults a modulation of the P300 was observed, while for children the N400 response was modulated. For both children and adults, the size of the ERP modulation in posterior electrodes was associated with individual differences in verbal working memory. These results highlight an important distinction between behavioral outcomes and their underlying neurocognitive mechanisms. Additionally, they provide insight into how arithmetic processing evolves over the course of development.