The importance of short-term memory for order in dissociating short-term memory and language deficits.

Several studies explored the relationship between verbal short-term memory (STM) and numerical cognition, but with inconclusive findings. The present study re-explored this relationship, by adopting the critical distinction between STM for item information (the items to be retained) and STM for order information (the order of the items within a list). We hypothesized that especially STM for order should be related to the development of numerical abilities, given that recent studies suggest the intervention of common processes during the representation of order information in STM and numerical tasks. We investigated item and order STM abilities and numerical processing abilities in 68 children during their third year in kindergarten. We observed that order STM abilities, but not item STM abilities, correlated significantly with performance on numerical order judgment and calculation tasks. These associations remained after control of interindividual differences in verbal and non-verbal cognitive efficiency. Our results suggest a specific relationship between order STM processes and numerical cognition, opening new perspectives for our understanding of the STM determinants of numerical cognition development.