A large body of research referred to as “multitasking” is based on dual-task paradigms, focusing on cognitive bottlenecks and crosstalk between perceptual encoding and response selection processes. However, everyday multitasking is different from the microstructure of rapid switching between laboratory tasks, and cognitive bottlenecks may be avoided by scheduling and interleaving deadlines and other task constraints in order to achieve multiple goals. 

We suggest that executive control demands of coordinating multiple ongoing activities can be alleviated by representing patterns of temporal deadlines in spatial relations. This spatial offloading hypothesis is consistent with observations showing that temporal relations are often represented in spatial terms. Our own behavioural studies show that spatial ability (mental rotation) predicts multitasking, but not dual-task, performance beyond individual differences in executive functions. 

Here, we test central predictions of the spatial offloading hypothesis using functional neuroimaging. We expect that cortical areas associated with spatial processing are selectively activated during multitasking. Moreover, these effects should reflect temporal task complexity, with accentuated patterns of activation in multiple tasks, but not in single- and dual-task performance, in which demands on cognitive control and temporal coordination are reduced. 

Twenty-four healthy, young adults completed a time-based monitoring task with varying number of component tasks (single, dual and multiple series of letters, running at different rates), while neural activity was measured using fMRI.

Results show increased activation with increasing number of component tasks in posterior parietal brain regions related to spatial processing. These findings suggest that multitasking involves spatial abilities and their underlying neural correlates.