Maintaining task set against distraction: The role of working memory in multitasking.

Multitasking, a common feature of everyday life, requires simultaneous maintenance and operation of a range of action-controlling task sets. We attempt to investigate the role of working memory in multitasking by means of the embedded task paradigm. This involves setting up a primary task with a variable task set, which then has to be maintained throughout the performance of a second embedded task with a fixed task set before it can be completed. We test the hypothesis that the capacity to maintain the two task sets so as to avoid mutual interference will depend on working memory. We use Baddeley and Hitch’s multicomponent working memory approach to investigate this. Experiment 1 uses articulatory suppression to examine the potential role of subvocal rehearsal, finding no impact on performance. Experiment 2 uses backward counting to impose an additional executive load, finding a major impact on performance even with the simple task of counting back in ones. This took the form of more pervasive effects of stimulus overlap that could be interpreted in terms of a change in the way the two tasks were managed. The differential impacts of the concurrent tasks indicated that multi-tasking is dependent on working memory, where it draws on limited capacity executive resources, but not on the capacity for temporary phonological storage.