From a computer science perspective, context switching is hugely expensive in humans, and that's why they are not good at multitasking. Strictly speaking, even

From a computer science perspective, context switching is hugely expensive in humans, and that's why they are not good at multitasking. Strictly speaking, even computers don't execute multiple tasks in parallel, at least not on the same core. Even with hyperthreading, each step in the pipeline can only work on one datum at a time. Computation is always serialised, and any context switching comes at a cost. It's just that in computers this cost doesn't matter so much, and/or it's outweighed by the benefits of weaving tasks into each other. Nevertheless, Multitasking is a myth, technically.