Verbal Working Memory in Sentence Comprehension

This paper investigates the nature of verbal working memory (WM) in sentence comprehension and provides evidence for overlapping pools of verbal WM resources between on-line sentence comprehension and other verbally-mediated tasks. We report the results of two dual-task experiments. In Experiment 1, participants simultaneously performed a selfpaced reading task and a self-paced arithmetic addition task in a 2x2 design crossing syntactic complexity (low, high) and arithmetic complexity (low, high). In addition to two main effects, the most interesting result was a significant interaction between syntactic and arithmetic complexity during the critical region of the linguistic materials: participants processed the complex/complex condition more slowly than would be expected if the two tasks relied on independent resource pools. To address a potential confound of shared attentional resources, Experiment 2 was conducted, where participants simultaneously performed a self-paced reading task and a self-paced spatial-rotation task in a similar 2x2 design crossing syntactic complexity with the complexity of the spatial task. As in Experiment 1, there were two main effects of complexity in the critical region. However, in contrast to Experiment 1, these effects were strictly additive, with no trace of interaction. The results of the two experiments therefore support a WM framework where online linguistic processing and on-line arithmetic processing rely on overlapping pools of verbal WM resources.