Human brains do not perform two tasks at the same time. Instead... brains can juggle tasks very rapidly, which leads us to erroneously believe we are doing two tasks at the same time. In reality, the brain is switching attention between tasks—performing only one task at a time. When trying to focus on more than one activity, your brain may become overloaded by the need to process information from two or more sources. Moreover, whenever you switch between tasks, your brain must spend time and energy redirecting its attention rather than thinking. Hope this helped!