Gade, M. , Druey, M. & Oberauer, K.
University of Zuerich, Institute for Psychology, General Psychology (Cognition)
Oberauer (2010) proposed a two-fold working memory system underlying the human ability to pursue goal-directed actions: a declarative working memory and a procedural one. Whereas the declarative part is thought to maintain and ensure access to representations of goal-relevant objects, the procedural part contains the representations of goal-relevant cognitive or overt operations. Capacity limits in declarative working memory have been studied in the working-memory literature. Capacity limits on procedural working memory have been revealed by research on action control, showing that people can typically hold only one task set available for direct control of action. The question of our research is whether the two systems have separate capacity limits or must share a common capacity. We combined classical tasks from both research areas in a dual-task experiment: letter recognition with varying memory set size served to manipulate declarative load, and digit classification with varying number of stimulus-response rules served to manipulate procedural load. The data suggest that declarative and procedural working memory operate independently. Two control experiments show that loading either one system with two tasks creates interference due to the irrelevant load in the second task.