"Smallwood learned that unhappy minds tend to wander in the past, while happy minds often ponder the future."

"He also became convinced that wandering among our memories is crucial to help prepare us for what is yet to come."

"I think it is more helpful to talk about the underlying processes: spontaneous thought, or the decoupling of attention from perception, which is what happens when our thoughts separate from our perception of the environment. Both these processes take place during mind-wandering and daydreaming."

"And instead of doing experiments where we just ask, “Are you mind-wandering?” we are now asking people a lot of different questions, like: “Are your thoughts detailed? Are they positive? Are they distracting you?”"

"Around the same time, brain imaging techniques were developing, and they were telling neuroscientists that something happens in the brain even when it isn’t occupied with a behavioral task."

"Large regions of the brain, now called the default mode network, did the opposite: If you gave people a task, the activity in these areas went down."

"It turns out to be more complicated than that. Initially, researchers were very sure that the default mode network rarely increased its activity during tasks. But these tasks were all externally focused — they involved doing something in the outside world."

"When researchers later asked people to do a task that doesn’t require them to interact with their environment — like think about the future — that activated the default mode network as well."

"But what both situations have in common is the person is using information from memory. I now think the default mode network is necessary for any thinking based on information from memory — and that includes mind-wandering."

"In a recent study, instead of asking people whether they were paying attention, we went one step further."

"So then, instead of reading, they’d remember the thing we showed them. We could cause them to remember."

"What we find is that the brain scans in this experiment look remarkably similar to mind-wandering. That is important: It gives us more control over the pattern of thinking than when it occurs spontaneously, like in naturally occurring mind-wandering."

"When we make people remember things from the list, we recapitulate quite a lot of what we saw in spontaneous mind-wandering."

"The interesting thing about social media and mind-wandering, I think, is that they may have similar motivations. Mind-wandering is very social."

"Social groups are so important to us as a species that we spend most of our time trying to anticipate what others are going to do, and I think social media is filling part of the gap that mind-wandering is trying to fill."

"When you’re mind-wandering, you’re ordering your own thoughts. Scrolling social media is more passive."

"For example, in our studies, people who are more intelligent don’t mind wandering so often when the task is hard but can do it more when tasks are easy."