Individual differences in proactive interference in verbal and visuospatial working memory

Proactive interference (PI) has been shown to affect working memory (WM) span as well as the predictive utility of WM span measures. However, most of the research on PI has been conducted using verbal memory items, and much less is known about the role of PI in the visuospatial domain. In order to further explore this issue, the present study used a within-subjects manipulation of PI that alternated clusters of trials with verbal and visuospatial to-be-remembered items. Although PI was shown to build and release across trials similarly in the two domains, important differences also were observed. The ability of verbal WM to predict performance on a measure of fluid intelligence was significantly affected by the amount of PI present, consistent with past research, but this proved not to be the case for visuospatial WM. Further, individuals' susceptibility to PI in one domain was relatively independent of their susceptibility in the other domain, suggesting that, contrary to some theories of executive function, individual differences in PI susceptibility may not be domain-general.