Here's a classic example: driving. There are a lot of things you have to be aware of and all of them contribute to your situational awareness and your ability to constantly adjust to the changing condition. But studies have shown that trying to drive while talking on a cell phone is the equivalent of drunk driving (University of Utah). The problem is that your brain simply CAN'T multitask well on two tasks, even when one of them "seems" to be trivial.
What women actually do better than men is task-switching - not true multitasking. It's exactly like what a CPU does in a computer - they task switch so fast that it _appears_ as if they are doing multiple things at once. In actuality, however, human studies have shown that people are incapable of concentrating on two things at the same time, and it requires concentration to perform most tasks at a quality level.
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