Contrary to popular belief, human beings cannot multitask. What we are capable of is handling a number of serial tasks in rapid succession, or mixing automatic tasks with those that are not so automatic. That’s one of the reasons that the NTSB reports that texting while driving is the functional equivalent of driving with a blood alcohol level three times the legal limit. You just can’t effectively attend to two things at once – even the superficially automatic ones.
5 Steps for Being Present | Psychology Today