Introduction
CORTEX
Multitasking is required in a variety of contexts in modern life, ranging from multimedia use to vehicle operation and scheduling of complex task sequences in an emergency room. Yet, performing even two simple cognitive tasks at the same time often results in between-task interference, e.g., when the engagement in an additional task impacts the processing of a prioritized task. Executive control processes, subsumed under the term task shielding serve to reduce this between-task interference by ensuring the correct binding of task-specific stimulus codes to respective response codes in each task to minimize the risk of response reversals and/or confusionRecent functional neuroimaging studies confirm a close link between dual-task performance and neural activity in brain regions associated with executive control, such as the dorsolateral prefrontal cortex (dlPFC, e.g.,Non-invasive brain stimulation techniques (NIBS), such as transcranial direct current stimulation (tDCS), have been applied to improve dual-task performance (e.g.,Studies focusing on improving executive control in dual tasks with tDCS have supported the claim that the dlPFC plays a central role in dual-task performance, especially when high demands on executive functioning are required (e.g.,In the present study, we aimed to test whether the application of atDCS over the left dlPFC can improve task shielding. We used a dual-task paradigm, in which both tasks were presented in close temporal proximity and shared processing similarities to give rise to crosstalk between the two tasks. Effective task shielding can be inferred from the size of the so-called backward crosstalk effect (BCE) that reflects to which extent Task 1 processing is affected by simultaneous Task 2 processing. Importantly, the smaller this backward crosstalk onto Task 1 performance, the more effective is task shielding and interference control