Earl Miller, a neuroscientist at MIT and one of the world experts on divided attention, says that our brains are “not wired to multitask well… When people think they’re multitasking, they’re actually just switching from one task to another very rapidly. And every time they do, there’s a cognitive cost in doing so.” So we’re not actually keeping a lot of balls in the air like an expert juggler; we’re more like a bad amateur plate spinner, frantically switching from one task to another, ignoring the one that is not right in front of us but worried it will come crashing down any minute. Even though we think we’re getting a lot done, ironically, multitasking makes us demonstrably less efficient.
I’ve always considered myself terrible at multitasking, which is sounding more and more like a positive quality rather than a negative one.
Asking the brain to shift attention from one activity to another causes the prefrontal cortex and striatum to burn up oxygenated glucose, the same fuel they need to stay on task. And the kind of rapid, continual shifting we do with multitasking causes the brain to burn through fuel so quickly that we feel exhausted and disoriented after even a short time. We’ve literally depleted the nutrients in our brain. This leads to compromises in both cognitive and physical performance. Among other things, repeated task switching leads to anxiety, which raises levels of the stress hormone cortisol in the brain, which in turn can lead to aggressive and impulsive behaviour. By contrast, staying on task is controlled by the anterior cingulate and the striatum, and once we engage the central executive mode, staying in that state uses less energy than multitasking and actually reduces the brain’s need for glucose.
I have definitely noticed “multitasking exhaustion” when I do try to multitask. I feel like 4pm Friday afternoon after a long week.
Unfortunately, I think trying to not multitask also has a negative cognitive effect. Because multitasking is so easy to do with technology and the internet, and because our brains like it, we have to exercise self-control to avoid it. But self-control is a limited resource.
This is why it’s important to remove unnecessary distractions that are a gateway to mulitasking.
To this end, I’ve turned off email notifications on my computer except for my wife and dissertation committee (sorry, Mom). I’m very selective about which push notifications are allowed on my phone. I figured out a way to compose an email without seeing my inbox. And I use SaneBox to automatically move unimportant email out of my inbox before I see it.