But Smallwood, now at Queen’s University in Ontario, Canada, forged ahead. He used as a tool a downright tedious computer task that aimed to replicate the kind of lapses in attention that cause us to pour milk into someone’s cup when they ask for black coffee. And he started by asking study participants some basic questions to better understand when and why minds tend to wander, and what topics they tend to wander to. After a while, he also started scanning participants’ brains, to get a glimpse of what was going on there during the mind wander.
Smallwood learned that unhappy spirits tend to wander into the past, while happy spirits often ponder the future. He also became convinced that wandering among our memories is crucial in helping us prepare for what is yet to come. Although certain types of mind wandering — like dwelling on problems that can’t be solved — can be associated with depression, Smallwood now thinks mind wandering is rarely a waste of time. It’s just our brain trying to do a little work when it feels like not much else is going on.
Smallwood, who in 2015 co-authored an influential overview of research on mental wandering in the Annual Journal of Psychology, is the first to admit that many questions remain unanswered.
This conversation has been edited for length and clarity.
Is mind wandering the same as daydreaming, or would you say they are different?
I think it’s a similar process used in a different context. When you’re on vacation and have plenty of free time, you might say you’re daydreaming about what you’d like to do next. But when you are under pressure to perform, you would experience the same thoughts as mind wandering.
I think it’s more useful to talk about the underlying processes: spontaneous thought, or the decoupling of attention from perception, which occurs when our thoughts become separated from our perception of the environment. Both of these processes take place during mind wandering and daydreaming.
It often takes us a while to catch ourselves wandering. How can you catch it to study it in other people?
In the beginning, we gave people experimental tasks that were really boring, so mind wandering often happened. We just asked once in a while, “Are you a mind wanderer?” while recording brain activity in an fMRI scanner.
But what I realized, after studying like that for a long time, is that if we want to know how thought works in the real world, where people do things like watch television or go for a run, the most of the data we’re never going to tell ourselves much.
We are therefore now trying to study these situations. And instead of doing experiments where we just ask, “Are you a mind wanderer?” we now ask people a lot of different questions, like, “Are your thoughts detailed? Are they positive? Are they distracting you?
How and why did you decide to study mind wandering?
I started studying mind wandering early in my career when I was young and naive.
I didn’t really understand at the time why no one was studying it. Psychology then focused on measurable outward behavior. I said to myself: this is not what I want to understand about my thoughts. What I want to know is: why do they come from, where do they come from, and why do they persist even though they interfere with attention to the here and now?
Around the same time, brain imaging techniques were developing that told neuroscientists that something was going on in the brain even when it was not busy with a behavioral task. Large areas of the brain, now called the Default Mode Network, did the opposite: if you gave people a task, activity in those areas decreased.
When scientists established this link between brain activity and mind wandering, it became all the rage. I was very lucky, as I hadn’t planned any of this when I started my PhD at the University of Strathclyde in Glasgow. But I saw it all unfold.
Would you say then that mind wandering is our brain’s default mode?
It turns out to be more complicated than that. Initially, the researchers were very confident that the network in default mode rarely increased its activity during tasks. But these tasks were all outward-oriented – they involved doing something in the outside world. When the researchers then asked people to perform a task that didn’t require them to interact with their environment, such as thinking about the future, this also activated the network in default mode.
More recently, we’ve identified much simpler tasks that also enable networking in default mode. If you let people look at a series of shapes like triangles or squares on a screen, and every once in a while you surprise them and ask them something – like, “On the last try, which side was the triangle on? – regions in the network default mode increases activity when making this decision. It’s a tough observation if you think the default mode network is just a mind-blowing system.
But what both situations have in common is that the person is using information from memory. I now believe that default mode networking is necessary for any thinking based on information from memory – and that includes mind wandering.
Would it be possible to demonstrate that this is indeed the case?
In a recent study, instead of asking people if they were paying attention, we went further. People were in a scanner reading short factual sentences on a screen. Occasionally, we’d show them a prompt that said “Remember,” followed by an item from a list of things from their past that they had provided earlier. So instead of reading, they remembered what we showed them. We could get them to remember.
What we find is that the brain scans of this experiment look remarkably like mind wandering. This is important: it gives us more control over the thought pattern than when it occurs spontaneously, as in the natural wandering of the mind. Of course, this is also a weakness, because it is not spontaneous. But we have already done a lot of spontaneous studies.
When we get people to remember the things on the list, we recap much of what we’ve seen in spontaneous mind wandering. This suggests that at least some of the activity we see when spirits wander is indeed associated with retrieving memories. We now think that the decoupling between attention and perception happens because people remember.
These days, it seems like many of the idle moments our minds would have wandered through before have now shifted to scrolling through our phones. How do you think this might change how our brain works?
What’s interesting about social media and mind wandering, I think, is that they can have similar motivations. Mind wandering is very social. In our studies, we lock people in little cubicles and have them do these chores and they keep coming out and saying, “I’m thinking of my friends. This tells us that following others is very important to people.
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 fills some of the void that mind wandering tries to fill. It’s like sharing information on social media: you can try to imagine what your friend is doing or you can just find out online. Of course, there is an important difference: when you wander in your mind, you command your own thoughts. Scrolling through social networks is more passive.
Could there be a way for us to suppress mind wandering in situations where it could be dangerous?
Mind wandering can be a boon and a curse, but I wouldn’t be sure we still know when it would be a good idea to stop it. In our current studies, we try to map how people think across a range of different types of tasks. We hope this approach will help us identify when mind wandering is likely to be helpful or not – and when we should try to control it and when we shouldn’t.
For example, in our studies, smarter people don’t mind wandering so often when the task is difficult, but may do so more when the tasks are easy. They may take advantage of downtime when the outside world does not demand their attention to think about other important matters. This highlights the uncertainty about whether mind wandering is always a bad thing, as this type of result implies that it is likely to be useful in certain circumstances.
This map – of how people think in different situations – has become very important in our research. This is the work I will focus on now, probably for the rest of my career.
This article originally appeared in Knowable magazine, an independent journalism venture of Annual Reviews. Register to receive the newsletter.