As neurologist Marcus Raichle learned after decades of looking at the brain, our minds are wired to wander. Wandering is their default. Whenever our thoughts are suspended between specific, discrete, goal-directed activities, the brain reverts to a so-called baseline, ‘resting’ state — but don’t let the word fool you, because the brain isn’t at rest at all. Instead, it experiences tonic activity in what’s now known as the DMN, the default mode network: the posterior cingulate cortex, the adjacent precuneus, and the medial prefrontal cortex. This baseline activation suggests that the brain is constantly gathering information from both the external world and our internal states, and what’s more, that it is monitoring that information for signs of something that is worth its attention. And while such a state of readiness could be useful from an evolutionary standpoint, allowing us to detect potential predators, to think abstractly and make future plans, it also signifies something else: our minds are made to wander. That is their resting state. Anything more requires an act of conscious will.
The modern emphasis on multitasking plays into our natural tendencies quite well, often in frustrating ways. Every new input, every new demand that we place on our attention is like a possible predator: Oooh, says the brain. Maybe I should pay attention to that instead. And then along comes something else. We can feed our mind wandering ad infinitum. The result? We pay attention to everything and nothing as a matter of course. While our minds might be made to wander, they are not made to switch activities at anything approaching the speed of modern demands. We were supposed to remain ever ready to engage, but not to engage with multiple things at once, or even in rapid succession.