Multitasking is not a real thing. In theory, we have the potential to devote 100% focus to a task. But that’s just a single task. We can’t give 100% to more than a single task.
It is almost unheard of that a horse has zero focus, but a lot of people are taught that a horse’s attention is either on or it’s off. There is a belief among some that a horse only has room for one thought in its head.