The nature of working memory in linguistic, arithmetic and spatial integration processes

This paper reports the results of four dual-task experiments that were designed to determine the extent of domain-specificity of the verbal working memory resources used in linguistic integrations. To address this question, syntactic complexity was crossed in a 2 × 2 design with the complexity of a secondary task, which involved either (1) arithmetic integration processes and therefore relied on the use of verbal working memory, or (2) spatial integration processes. Experiments 1 and 2 crossed syntactic complexity and arithmetic complexity, and each revealed two main effects and a super-additive interaction during the critical region of the linguistic materials. Experiments 3 and 4 crossed syntactic complexity and the complexity of a spatial integration task, which does not rely on verbal working memory resources. Similar to Experiments 1 and 2, there were two main effects, but in contrast to Experiments 1 and 2, no interaction was observed in either experiment. The results of the four experiments show that linguistic processing interacts on-line with tasks that involve arithmetic but not spatial integration processes, suggesting that linguistic processing and other verbal working memory tasks that involve similar integration processes rely on a shared pool of working memory resources.