This week Earl Miller, a professor of neuroscience at The Picower Institute for Learning and Memory at MIT, breaks down why you shouldn’t multitask.

Here’s practical advice from a neuroscientist: Don’t try to multitask. It ruins productivity, causes mistakes, and impedes creative thought. Many of you are probably thinking, “but I’m good at it!” Sadly, that’s an illusion. As humans, we have a very limited capacity for simultaneous thought — we can only hold a little bit of information in the mind at any single moment.

Our brains, however, delude us into thinking we can do more. To understand how this happens, it helps to think about how we physically see the world. Barring visual impairments, we perceive our surroundings via a video camera-like, wide-angle lens. Or at least that’s how it seems. In reality, our eyes are constantly darting around, 3-4 times per second, taking in our surroundings in snippets. The end looks like one image, but that’s just because our brains paper these individual pieces together to create a complete picture.

The same is true for multitasking. When we toggle between tasks, the process often feels seamless — but in reality, it requires a series of small shifts. Say you stop writing a pitch for a client in order to check an incoming email — when you finally return to the pitch, your brain has to expend valuable mental energy refocusing on the task, backtracking, and fixing errors. Not only does this waste time, it decreases your ability to be creative. Innovative thinking, after all, comes from extended concentration, i.e. the ability to follow an idea of thought down a network of new paths. When you try to multitask, you typically don’t get far enough down any road to stumble upon something original because you’re constantly switching and backtracking.

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If you’re thinking “this probably just applies to other people” — wrong. In fact, studies show that people who think they are good at multitasking generally have a lower capacity for simultaneous thought. It’s a rationalization fest. Frequent offenders are bad at ignoring distractions, but instead of trying to improve their ability to focus, they convince themselves that multitasking increases productivity.

Maybe you’re wondering, “if multitasking is bad, why do we have the urge to do it?” The answer likely has to do with how our brains evolved. Back in prehistoric days, any new piece of information might be critical — a rustling in the bushes, for example, could mean a tiger was about to leap. Thus, it was adaptive for our brains to seek out and pay attention to new information. Unfortunately, what was once an evolutionary advantage has become a distraction. In today’s modern society where our lives are rarely on the line, the ceaseless onslaught of information has the potential to cripple us. Our brains aren’t equipped to handle the sensory overload.

Here’s what to do about it.

Start by blocking out a period of time to focus. Eliminate as many distractions as possible: Put away your phone, turn off extra computer screens, shut down your email if you have to. Don’t try to mono-task by willpower alone; it’s too hard to fight the thirst for new information. Instead, prevent the urge by removing temptation. If you find yourself unable to concentrate, try taking a short break and move around. Increasing blood flow to your brain can help restore focus.

One final word of advice: Please, please put away your phone when you drive. Mute it, put it out of reach. (Hands-free headsets don’t help; it’s the cognitive demands of conversation that causes the distraction.) Being able to pay attention to your driving while on the phone is another delusion — the work of David Stayer and colleagues shows that it causes drivers to miss as much as half of the things in front of them. Multitasking while driving is just plain dangerous.