Brains can’t work and daydream at the same time

From the New York Times: "Our brains have two dominant modes of attention: the task-positive network and the task-negative network. The task-positive network is active when you're actively engaged in a task, focused on it, and undistracted; neuroscientists have taken to calling it the central executive. The task-negative network is active when your mind is wandering; this is the daydreaming mode. These two attentional networks operate like a seesaw in the brain: when one is active the other is not."