Obviously, all tasks are not created equal. It requires far more concentration to do calculus than sing along with Fifth Harmony (provided you know all the lyrics by heart). To that end, it's possible to do some tasks simultaneously.
"Tasks that are automatic or don't require much attention allow for a sort of multitasking ... But it's hopeless to try to conduct two or more tasks at once when each of them requires that we pay attention to what we're doing," Dr. Susana Martinez-Conde, neuroscientist and co-author of "Sleights of Mind: What the Neuroscience of Magic Reveals About Our Everyday Deceptions" explains in an email interview. "A much better and productive strategy is to carry out the two tasks in sequence. We must also consider the sort of situation we're in, and its consequences. Texting a friend while we watch a movie may mean that we miss a critical point of the plot (not a big loss), but texting a friend while driving may have far more serious consequences."
Although it might not be as impressive as X-ray vision or web-slinging, there are some who are supertaskers. "Researchers from the University of Utah discovered that 2.5 percent of a group of 200 undergraduates were exceptional performers in a simulation that mimicked driving while talking on a cell phone. This study suggests that there are people for whom multitasking, even with complex tasks, can be effective," Gratias writes in her e-book, "Love Your Calendar...and be monogamous." The jury's still out on why certain people are supertaskers, but researchers hypothesize that their brain's unique abilities could be due to genetics.
Clear urges caution against assuming membership in this category, however. "Some jobs really do require a person to be exceptional at handling multiple, simultaneously occurring events, and some people are supertaskers," he says. "However, don't create the need to multitask where it doesn't already exist, and avoid habitual multitasking simply because 'that's the way I've always done it.'"