mind wandering examples

Mind Wandering: Examples, Symptoms And Treatment

Examples and types of mind wandering, the symptoms, benefits and potential treatments for a drifting mind.

Up to half of our daily thoughts involve mind wandering or a drifting mind.

Unfortunately, when left to its own devices the mind almost always wanders to negative thoughts and brings us down.

Mind wandering in general is often associated with increased stress and a lack of academic success.

But daydreaming can be seen as a sign of being more creative and having higher intelligence, research finds.

Those who report more daydreaming have higher intellectual abilities and their brains work more efficiently.

Here are more examples of mind wandering from the research, including symptoms, benefits and potential treatments.

1. Memory benefits

Part of the function of mind wandering is to allow the brain to work on our memories, research suggests.

Mind wandering — which may make up 50 percent of our daily thinking time — is experienced as a kind of zoning out from what is going on around us.

During this time, researchers have found, many areas of the brain quiet themselves to focus on output from the hippocampus.

The output from the hippocampus is very weak, which the researchers charmingly describe as whispering .

So, the rest of the brain has to be particularly quiet to listen and further encode these memories for long-term storage.

2. Types of mind wandering

There are two types of mind wandering — each with a different experience.

Mind wandering tends to be seen in a negative way, but zoning out on purpose can help creative thinking and problems solving.

Research has identified a vital difference between intentional and unintentional mind wandering.

It reveals how intentional mind wandering feels different from accidental mind wandering.

The study’s authors explain:

“We suspect that when people are completing an easy task, they may be inclined to deliberately disengage from the task and engage in mind wandering. This might be the case because easy tasks tend to be rather boring, or because people realize that they can get away with mind wandering without sacrificing performance. Conversely, when completing a difficult task, people really need to focus on the task in order to perform well, so if they do mind-wander, their mind wandering should be more likely to occur unintentionally.”

3. Intentional daydreaming

Some types of mind wandering may be highly beneficial to our brains, and our futures.

Intentional daydreaming is linked to a thicker cortex (a good thing) in certain key areas of the brain, research finds.

Directing the mind to wander is a cognitive skill that can be beneficial in some contexts.

For example, it can allow us to mentally rehearse upcoming events, or solve problems we might encounter.

In other words, it allows the brain to work out possible futures for us.

So, mind wandering is not always a failure of self-control that is inevitably linked to mistakes.

The key is whether it is intentional or not.

4. Creative mind wandering example

The incubation effect : this is simply that taking a break from a problem often brings an insight later on.

We know it from experience and psychological research has proven it.

About 50 different studies have been carried out on the incubation effect and three-quarters of them find an effect.

Mind wandering probably plays an important role in the process of creative problem-solving.

A study has found that a moderately engaging activity like showering or walking produces more creative ideas.

They appear to work because they engage the mind somewhat, but also allow it freedom to wander.

5. Mind wandering and depression

Mind wandering is often seen in a negative way, though, and with good reason.

The minds of people with depressive tendencies wander in characteristic ways, research finds .

Depressive people find their thoughts automatically narrowing to negative past events.

Instead of naturally jumping to other more positive topics, as other people’s do, their thoughts focus on the negative.

This style of thinking is called  rumination , and is strongly linked to depression.

Mind wandering towards depressive thoughts is a key sign of depressive tendencies, but is not the usual pattern for people.

6. Signs of mind wandering

When a person starts to blink more rapidly, it suggests their mind is wandering, research finds.

Blinking sets up a tiny barrier against the outside world, allowing the brain to focus on something different.

The researchers were inspired by neuroscientific findings that parts of the brain are less active when the mind wanders.

Dr Daniel Smilek, the study’s first author, said:

“And we thought, OK, if that’s the case, maybe we’d see that the body would start to do things to prevent the brain from receiving external information. The simplest thing that might happen is you might close your eyes more.”

They were right — the results showed people blinked more when they had switched off from the text and were thinking of something else.

7. Stop mind wandering while reading

Paying attention to what you are reading can be hard — especially in this age of endless distraction.

Practising meditation, though, can help improve your focus while reading, a study finds .

Maintaining attention when reading can be difficult, as the study’s authors write:

“It is challenging for individuals to maintain their attention on ongoing cognitive tasks without being distracted by task-unrelated thought. The wandering mind is thus a considerable obstacle when attention must be maintained over time. Mental training through meditation has been proposed as an effective method of attenuating the ebb and flow of attention to thoughts and feelings that distract from one’s foremost present goals.”

8. Anxiety treatment

A lack of concentration can be combated using a short form of mindfulness training, a study of undergraduates finds.

Just ten minutes of mindfulness each day is also an effective treatment against repetitive anxious thoughts, research reveals.

People in the study who meditated for only a short period found it easier to focus on their present-moment external experience rather than their internal thoughts.

Mr Mengran Xu, the study’s first author, said:

“Our results indicate that mindfulness training may have protective effects on mind wandering for anxious individuals. We also found that meditation practice appears to help anxious people to shift their attention from their own internal worries to the present-moment external world, which enables better focus on a task at hand.”

Author: Jeremy Dean

Psychologist, Jeremy Dean, PhD is the founder and author of PsyBlog. He holds a doctorate in psychology from University College London and two other advanced degrees in psychology. He has been writing about scientific research on PsyBlog since 2004. He is also the author of the book "Making Habits, Breaking Habits" (Da Capo, 2013) and several ebooks. View all posts by Jeremy Dean

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It’s normal for your mind to wander. Here’s how to maximise the benefits

Psychology researcher, Bond University

Associate Professor in Psychology, Bond University

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The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

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Have you ever found yourself thinking about loved ones during a boring meeting? Or going over the plot of a movie you recently watched during a drive to the supermarket?

This is the cognitive phenomenon known as “ mind wandering ”. Research suggests it can account for up to 50% of our waking cognition (our mental processes when awake) in both western and non-western societies .

So what can help make this time productive and beneficial?

Mind wandering is not daydreaming

Mind wandering is often used interchangeably with daydreaming. They are both considered types of inattention but are not the same thing.

Mind wandering is related to a primary task, such as reading a book, listening to a lecture, or attending a meeting. The mind withdraws from that task and focuses on internally generated, unrelated thoughts.

On the other hand, daydreaming does not involve a primary, active task. For example, daydreaming would be thinking about an ex-partner while travelling on a bus and gazing out the window. Or lying in bed and thinking about what it might be like to go on a holiday overseas.

If you were driving the bus or making the bed and your thoughts diverted from the primary task, this would be classed as mind wandering.

The benefits of mind wandering

Mind wandering is believed to play an important role in generating new ideas , conclusions or insights (also known as “aha! moments”). This is because it can give your mind a break and free it up to think more creatively.

This type of creativity does not always have to be related to creative pursuits (such as writing a song or making an artwork). It could include a new way to approach a university or school assignment or a project at work. Another benefit of mind wandering is relief from boredom, providing the opportunity to mentally retreat from a monotonous task.

For example, someone who does not enjoy washing dishes could think about their upcoming weekend plans while doing the chore. In this instance, mind wandering assists in “passing the time” during an uninteresting task.

Mind wandering also tends to be future-oriented. This can provide an opportunity to reflect upon and plan future goals, big or small. For example, what steps do I need to take to get a job after graduation? Or, what am I going to make for dinner tomorrow?

Read more: Alpha, beta, theta: what are brain states and brain waves? And can we control them?

What are the risks?

Mind wandering is not always beneficial, however. It can mean you miss out on crucial information. For example, there could be disruptions in learning if a student engages in mind wandering during a lesson that covers exam details. Or an important building block for learning.

Some tasks also require a lot of concentration in order to be safe. If you’re thinking about a recent argument with a partner while driving, you run the risk of having an accident.

That being said, it can be more difficult for some people to control their mind wandering. For example, mind wandering is more prevalent in people with ADHD.

Read more: How your brain decides what to think

What can you do to maximise the benefits?

There are several things you can do to maximise the benefits of mind wandering.

• be aware : awareness of mind wandering allows you to take note of and make use of any productive thoughts. Alternatively, if it is not a good time to mind wander it can help bring your attention back to the task at hand

context matters : try to keep mind wandering to non-demanding tasks rather than demanding tasks. Otherwise, mind wandering could be unproductive or unsafe. For example, try think about that big presentation during a car wash rather than when driving to and from the car wash

content matters : if possible, try to keep the content positive. Research has found , keeping your thoughts more positive, specific and concrete (and less about “you”), is associated with better wellbeing. For example, thinking about tasks to meet upcoming work deadlines could be more productive than ruminating about how you felt stressed or failed to meet past deadlines.

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Why Do Our Minds Wander?

A scientist says mind-wandering or daydreaming help prepare us for the future

Tim Vernimmen, Knowable Magazine

When psychologist Jonathan Smallwood set out to study mind-wandering about 25 years ago, few of his peers thought that was a very good idea. How could one hope to investigate these spontaneous and unpredictable thoughts that crop up when people stop paying attention to their surroundings and the task at hand? Thoughts that couldn’t be linked to any measurable outward behavior?

But Smallwood, now at Queen’s University in Ontario, Canada, forged ahead. He used as his tool a downright tedious computer task that was intended to reproduce the kinds of lapses of attention that cause us to pour milk into someone’s cup when they asked for black coffee. And he started out by asking study participants a few basic questions to gain insight into when and why minds tend to wander, and what subjects they tend to wander toward. After a while, he began to scan participants’ brains as well, to catch a glimpse of what was going on in there during mind-wandering.

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. Though some kinds of mind-wandering — such as dwelling on problems that can’t be fixed — may be associated with depression , Smallwood now believes mind-wandering is rarely a waste of time. It is merely our brain trying to get a bit of work done when it is under the impression that there isn’t much else going on.

Smallwood, who coauthored an influential 2015 overview of mind-wandering research in the Annual Review of Psychology, is the first to admit that many questions remain to be answered.

This conversation has been edited for length and clarity.

Is mind-wandering the same thing as daydreaming, or would you say those are different?

I think it’s a similar process used in a different context. When you’re on holiday, and you’ve got lots of free time, you might say you’re daydreaming about what you’d like to do next. But when you’re under pressure to perform, you’d experience the same thoughts as mind-wandering.

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.

It often takes us a while to catch ourselves mind-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 that mind-wandering would happen a lot. We would just ask from time to time, “Are you mind-wandering?” while recording the brain’s activity in an fMRI scanner.

But what I’ve realized, after doing studies like that for a long time, is that if we want to know how thinking works in the real world, where people are doing things like watching TV or going for a run, most of the data we have are never going to tell us very much.

So we are now trying to study these situations . 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?”

How and why did you decide to study mind-wandering?

I started studying mind-wandering at the start of my career, when I was young and naive.

I didn’t really understand at the time why nobody was studying it. Psychology was focused on measurable, outward behavior then. I thought to myself: That’s not what I want to understand about my thoughts. What I want to know is: Why do they come, where do they come from, and why do they persist even if they interfere with attention to the here and now?

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.

When scientists made this link between brain activity and mind-wandering, it became fashionable. I’ve been very lucky, because I hadn’t anticipated any of that when I started my PhD, at the University of Strathclyde in Glasgow. But I’ve seen it all pan out.

Would you say, then, that mind-wandering is the default mode for our brains?

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.

More recently, we have identified much simpler tasks that also activate the default mode network. If you let people watch a series of shapes like triangles or squares on a screen, and every so often you surprise them and ask something — like, “In the last trial, which side was the triangle on?”— regions within the default mode network increase activity when they’re making that decision . That’s a challenging observation if you think the default mode network is just a mind-wandering system.

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.

Would it be possible to demonstrate that this is indeed the case?

In a recent study, instead of asking people whether they were paying attention, we went one step 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’d provided earlier. 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. Of course, that is a weakness as well, because it’s not spontaneous. But we’ve already done lots of spontaneous studies.

When we make people remember things from the list, we recapitulate quite a lot of what we saw in spontaneous mind-wandering. This suggests that at least some of the activity we see when minds wander is indeed associated with the retrieval of memories. We now think the decoupling between attention and perception happens because people are remembering.

Have you asked people what their minds are wandering toward?

The past and future seem to really dominate people’s thinking . I think things like mind-wandering are attempts by the brain to make sense of what has happened, so that we can behave better in the future. I think this type of thinking is a really ingrained part of how our species has conquered the world. Almost nothing we’re doing at any moment in time can be pinpointed as only mattering then.

That’s a defining difference. By that, I don’t mean that other animals can’t imagine the future, but that our world is built upon our ability to do so, and to learn from the past to build a better future. I think animals that focused only on the present were outcompeted by others that remembered things from the past and could focus on future goals, for millions of years — until you got humans, a species that’s obsessed with taking things that happened and using them to gain added value for future behavior.

People are also, very often, mind-wandering about social situations . This makes sense, because we have to work with other people to achieve almost all of our goals, and other people are much more unpredictable than the Sun rising in the morning.

Though it is clearly useful, isn’t it also very depressing to keep returning to issues from the past?

It certainly can be. We have found that mind-wandering about the past tends to be associated with negative mood.

Let me give you an example of what I think may be happening. For a scientist like me, coming up with creative solutions to scientific problems through mind-wandering is very rewarding. But you can imagine that if my situation changes and I end up with a set of problems I can’t fix, the habit of going over the past may become difficult to break. My brain will keep activating the problem-solving system, even if it can’t do anything to fix the problem, because now my problems are things like getting divorced and my partner doesn’t want any more to do with me. If such a thing happens and all I’ve got is an imaginative problem-solving system, it’s not going to help me, it’s just going to be upsetting. I just have to let it go.

That’s where I think mindfulness could be useful, because the idea of mindfulness is to bring your attention to the moment. So if I’d be more mindful, I’d be going into problem-solving mode less often.

If you spend long enough practicing being in the moment, maybe that becomes a habit. It’s about being able to control your mind-wandering. Cognitive behavioral therapy for depression, which aims to help people change how they think and behave, is another way to reduce harmful mind-wandering.

Nowadays, it seems that many of the idle moments in which our minds would previously have wandered are now spent scrolling our phones. How do you think that might change how our brain functions?

The interesting thing about social media and mind-wandering, I think, is that they may have similar motivations. Mind-wandering is very social. In our studies , we’re locking people in small booths and making them do these tasks and they keep coming out and saying, “I’m thinking about my friends.” That’s telling us that keeping up with 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 is filling part of the gap that mind-wandering is trying to fill. It’s like mainlining social information: You can try to imagine what your friend is doing, or you can just find out online. Though, of course, there is an important difference: When you’re mind-wandering, you’re ordering your own thoughts. Scrolling social media is more passive.

Could there be a way for us to suppress mind-wandering in situations where it might be dangerous?

Mind-wandering can be a benefit and a curse, but I wouldn’t be confident that we know yet when it would be a good idea to stop it. In our studies at the moment, we are trying 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 useful or not — and when we should try to control it and when we shouldn’t.

For example, in our studies, people who are more intelligent don’t mind wander so often when the task is hard but can do it more when tasks are easy . It is possible that they are using the idle time when the external world is not demanding their attention to think about other important matters. This highlights the uncertainty about whether mind wandering is always a bad thing, because this sort of result implies it is likely to be useful under some circumstances.

This map — of how people think in different situations — has become very important in our research. This is the work I’m going to focus on now, probably for the rest of my career.

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How to Let Your Mind Wander

Research suggests that people with freely moving thoughts are happier. Easy, repetitive activities like walking can help get you in the right mindset.

By Malia Wollan

“Sometimes you just want to let your mind go free,” says Julia Kam, a cognitive neuroscientist who directs the Internal Attention Lab at the University of Calgary. Kam became interested in her subject 15 years ago as an undergraduate struggling with her own distracted thoughts during lectures. “I came into the field wanting to find a cure,” she says. But the deeper she got into research, the more she came to appreciate the freedom of an unfocused mind. “When your thoughts are just jumping from one topic to the next without an overarching theme or goal, that can be very liberating,” she says.

Researchers have found that people spend up to 50 percent of their time mind-wandering. Some internal thinking can be detrimental, especially the churning, ruminative sort often associated with depression and anxiety. Try instead to cultivate what psychologists call freely moving thoughts. Such nimble thinking might start with a yearning to see your grandmother, then careen to that feeling you get when looking down at clouds from an airplane, and then suddenly you’re pondering how deep you’d have to bore into the earth below your feet before you hit magma. Research suggests that people who do more of that type of mind-wandering are happier.

Facilitate unconstrained thinking by engaging in an easy, repetitive activity like walking; avoid it during riskier undertakings like driving. You’ll find it harder to go free-ranging if you’re myopically worried about something in your personal life, like an illness or an argument with a spouse.

For a recent study, Kam hooked subjects up for an electroencephalogram and then had them do a mundane task on a keyboard while periodically asking them about their thoughts. She was able to see, for the first time, a distinct neural marker for freely moving thoughts, which caused an increase in alpha waves in the brain’s frontal cortex. This is the same region where scientists see alpha waves in people doing creative problem-solving. We live in a culture that values work and productivity over almost everything else, but remember, your mind is yours. Make space to think in idle ways unrelated to tasks. “It can replenish you,” Kam says.

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The Wandering Mind: How the Brain Allows Us to Mentally Wander Off to Another Time and Place

A unique human characteristic is our ability to mind wander—these are periods of time when our attention drifts away from the task-at-hand to focus on thoughts that are unrelated to the task. Mind wandering has some benefits, such as increased creativity, but it also has some negative consequences, such as mistakes in the task we are supposed to be performing. Interestingly, we spend up to half of our waking hours mind wandering. How does the brain help us accomplish that? Research suggests that when we mind wander, our responses to information from the external world around us are disrupted. In other words, our brain’s resources are shifted away from processing information from the external environment and redirected to our internal world, which allows us to mentally wander off to another time and place. Even though we pay less attention to the external world during mind wandering, our ability to detect unexpected events in our surrounding environment is preserved. This suggests that we are quite clever about what we ignore or pay attention to in the external environment, even when we mind wander.

How Do Scientists Define Mind Wandering?

Imagine this: you are sitting in a classroom on a sunny day as your science teacher enthusiastically tells you what our brain is capable of doing. Initially, you pay close attention to what the teacher is saying. But the sound of the words coming out of her mouth gradually fade away as you notice your stomach growling and you begin to think about that delicious ice cream you had last night. Have you ever caught yourself mind wandering in similar situations, where your eyes are fixed on your teacher, friends, or parents, but your mind has secretly wandered off to another time and place? You may be recalling the last sports game you watched, or fantasizing about going to the new amusement park this upcoming weekend, or humming your favorite tune that you just cannot get out of your head. This experience is what scientists call mind wandering, which is a period of time when we are focused on things that are not related to the ongoing task or what is actually going on around us (as shown in Figure 1 ).

• Figure 1 - Real-world example of on-task and mind wandering states among students in a classroom.
• In a science class in which the teacher asks a question about the brain, some students may be focused on what is being taught, while others may be thinking about yesterday’s basketball tournament, humming their favorite tune, or thinking about getting ice cream after school. The students thinking about the brain during class would be considered to be “on task,” while students thinking about things unrelated to the brain would be considered to be “mind wandering.”

Our Tendency to Mind Wander

Humans on average spend up to half of their waking hours mind wandering. There are differences across individuals in their tendency to mind wander and many factors that affect this tendency. For instance, older adults on average tend to mind wander less than younger adults. Also, individuals who are often sad or worried mind wander more frequently compared with individuals who are happy and have nothing to worry about. We also mind wander more when we perform tasks that we are used to doing, compared with when we perform novel and challenging tasks. There are also different types of mind wandering. For example, we may sometimes mind wander on purpose when we are bored with what we are currently doing. Other times, our mind accidentally wanders off without us noticing.

What are the Pros and Cons of Mind Wandering?

Since we spend so much time mind wandering, does this mean that mind wandering is good for us or not? There are certainly benefits to mind wandering. For example, one of the things the mind does when it wanders is to make plans about the future. In fact, we are more likely to make plans when we mind wander than we are to fantasize about unrealistic situations. Planning ahead is a good use of time as it allows us to efficiently carry out our day-to-day tasks, such as finishing homework, practicing soccer, and preparing for a performance. When mind wandering, we are also likely to reflect upon ourselves. This process of thinking about how we think, behave, and interact with others around us is a crucial part of our self-identity. Mind wandering has also been tied to creative problem-solving. There are times when we get stuck on a challenging math problem or feel uninspired to paint or make music, and research suggests that taking a break from thinking about these problems and letting the mind wander off to another topic may eventually lead to an “aha” moment, in which we come up with a creative solution or idea.

However, mind wandering can also have negative outcomes. For example, mind wandering in class means you miss out on what is being taught, and mind wandering while doing your homework may result in mistakes. Taken to an extreme, people who are diagnosed with depression constantly engage in their own thoughts about their problems or other negative experiences. In contrast, individuals diagnosed with attention-deficit/hyperactivity disorder who continually change their focus of attention may have a hard time completing a task. Taken together, whether mind wandering is good or bad depends on when we mind wander and what we mind wander about [ 1 ].

Scientific Measures of Mind Wandering

If you were to conduct an experiment, how would you measure mind wandering? Scientists have come up with several methods, one of which is called experience sampling . As research volunteers are doing a computer task in a laboratory, or as they are doing chores in their day-to-day lives, they are asked at random intervals to report their attention state. That is, they have to stop what they are doing and ask themselves what they were thinking about in the moment: “Was I on-task?” (that is, was I paying attention to the task-at-hand) or “Was I mind wandering?” (that is, did my mind wander off to another time and place). Therefore, experience sampling samples the volunteer’s in-the-moment experience, allowing scientists to understand how frequently people mind wander and how mind wandering affects the way people interact with their environments.

Scientists also study mind wandering by recording electroencephalogram (EEG) , a test that measures the electrical activity of the brain. This electrical activity, which looks like wavy lines during an EEG recording (see Figure 2 , Step 2), is observed in all parts of the brain and is present throughout the day, even when we are asleep. Measurements of the brain’s electrical activity help scientists understand how the brain allows us to think, speak, move, and do all the fun and creative and challenging things that we do! In order to record EEG, scientists place special sensors called electrodes on the scalp of a volunteer ( Figure 2 , Step 1), with each electrode recording activity of numerous neurons (brain cells) in the area under the electrode ( Figure 2 , Step 2). Scientists then examine the brain’s activity in response to images (such as a picture of a basketball in Figure 2 ) or sounds presented to the volunteer. The scientists present the same sound or picture to the volunteer multiple times and take the average of the brain’s activity in response to the image or sound, because that method results in a better EEG signal. The averaged brain activity produces something called an event-related potential (ERP) waveform that contains several high and low points, called peaks and troughs ( Figure 2 , Step 3), which represent the brain’s response to the image or sound over time. Some commonly seen peaks and troughs are assigned specific names as ERP components. For instance, a peak that occurs around 300 ms (only 3/10 of a second!) following the presentation of a picture or a sound is often called the P300 ERP component. Based on decades of research, scientists have shown that these ERP components reflect our brain’s response to events we see or hear. The size of the ERP components (measured in voltage) reflects how strong the response is, while the timing of these ERP components (measured in milliseconds) reflects the timing of the response. Now, PAUSE! I would like you to ask yourself, “Was I paying full attention to the previous sentence just now, or was I thinking about something else?” This is an example of experience sampling. And as you may realize now, when we are asked about our current attention state, we can quite accurately report it.

• Figure 2 - Recording electroencephalogram (EEG) in humans.
• Step 1. To record EEG, electrodes are attached to a cap that is placed on the scalp of a research volunteer. Step 2. Each wavy line represents the amount of activity recorded by each electrode. Research volunteers are usually presented with some images (e.g., a basketball) or sounds a number of times while their brain activity is being recorded. Step 3. Scientists calculate the average EEG activity across multiple presentations of the same picture/sound. This results in an Event-Related Potential (ERP) waveform, where time (in milliseconds) is plotted on the x-axis and the voltage (in microvolts, indicating the size of the ERP components) is plotted on the y-axis. On the x-axis, 0 indicates the time at which the stimulus (e.g., image of a basketball) was presented. The ERP waveforms contain multiple high and low points, called peaks and troughs. Some of the peaks and troughs are given specific labels. For example, the peak that occurs around 300 ms after an image is presented is often called the P300 ERP component.

What Happens to Our Interaction with the Environment When We Mind Wander?

Scientists have proposed an idea—called the “Decoupling Hypothesis”—stating that during mind wandering, the brain’s resources are shifted away from our surrounding environment and are redirected to our internal world in order to support our thoughts [ 2 ]. This hypothesis assumes that the brain has a certain amount of resources, which means that once mind wandering has used the resources it needs to focus on our thoughts, only a limited amount of brain resources remains for responding to our surrounding environment.

To test this hypothesis, scientists combined experience sampling with EEG to explore how mind wandering affects our interaction with the environment. One of the first studies to test this hypothesis asked research volunteers to categorize a series of images by responding whenever they saw rare targets (e.g., images of soccer balls) among a whole bunch of non-targets (e.g., images of basketballs). Throughout the task, EEG was recorded from the volunteers, and they were also asked at random times to report their attention state as “on task” or “mind wandering.” Based on their EEGs and experience sampling reports, scientists found that the brain’s response to the non-targets was reduced during periods of mind wandering compared with periods of being on task [ 3 ]. This can be seen in Figure 3A , where there is a smaller P300 ERP component during mind wandering (the green lines) compared with the P300 ERP component during the time when the volunteer was on task (the gray line). The data suggest that the brain’s response to events happening in our environment is disrupted when we engage in mind wandering.

• Figure 3 - Mind wandering affects our ability to process events in the environment.
• A. The brain’s processing of external events (e.g., images of basketballs and soccer balls) is reduced during periods of mind wandering. This is indicated by the smaller P300 ERP component during mind wandering (green lines) compared with on-task (gray line). The ERP waveform was recorded from the electrode site circled in red, which is located on the back of the head. B. Mind wandering impairs our ability to monitor our own performance, making it more likely that we will make mistakes. This is shown by the smaller feedback error-related negativity ERP component, a trough occurring around 250 ms, for mind wandering (green line) compared with on-task (gray line). The ERP waveform was recorded from the electrode site circled in red, which is located near the front of the head.

Have you ever noticed that if your mind wanders while you are doing homework, you are more likely to make mistakes? Many experiments have also shown that this happens! This led some scientists to question what is happening in the brain when we make mistakes. They specifically measured something called the feedback error-related negativity ERP component, which gives scientists an idea of how closely we are monitoring the accuracy of our responses when we perform a task. The scientists found that the feedback error-related negativity ERP component was reduced during mind wandering compared with on-task periods, as shown in Figure 3B . This suggests that mind wandering negatively affects our ability to monitor our performance and adjust our behavior, making it more likely that we will make mistakes [ 4 ]. All of these studies provide evidence supporting the hypothesis that when the mind wanders, our responses to what is going on in the environment around us are disrupted.

Does Mind Wandering Impair all Responses to the Environment?

At this point, you may wonder: are all responses to the world around us impaired during mind wandering? This seems unlikely, because we are usually quite capable of responding to the external environment even when we mind wander. For example, even though we may mind wander a lot while walking, most of us rarely bump into things as we walk from place to place. A group of scientists asked the same question and looked specifically at whether we can still pay attention to our environment at some level even when we are mind wandering. To test this question, research volunteers were asked to read a book while they were listening to some tones unrelated to the book. Most of the tones were identical, but among these identical tones was rare and different tone that naturally grabbed the attention of the volunteers. These scientists found that the volunteers paid just as much attention to this rare tone when they were mind wandering compared to when they were on task. In other words, our minds appear to be quite smart about which attention processes to disrupt and which processes to preserve during mind wandering. Under normal circumstances, our minds ignore some of the ordinary events in our environment in order for us to maintain a train of thought. However, when an unexpected event occurs in the environment, one that is potentially dangerous, our brain knows to shift our attention to the external environment so that we can respond to the potentially dangerous event. Imagine walking down the street and thinking about the movie you want to watch this weekend. While doing this, you may not clearly perceive the noise of the car engines or the pedestrians chatting around you. However, if a car suddenly honks loudly, you will hear the honk immediately, which will snap you out of your mind wandering. Therefore, even when the mind is wandering, we are still clever about what we ignore and what we pay attention to in the external environment, allowing us to smartly respond to the unusual, or potentially dangerous, events that may require us to focus our attention back on the external environment.

In summary, the brain appears to support mind wandering by disrupting some of the brain processes that are involved in responding to our surrounding external environment. This ability is important for protecting our thoughts from external distractions and allowing us to fully engage in mind wandering. We are only beginning to understand this mysterious experience of thinking, and scientists are actively researching what goes on in the brain when we mind wander. Increasing our knowledge about mind wandering will help us better understand how to take advantage of its benefits while avoiding the problems linked to mind wandering.

Mind Wandering : ↑ Periods of time when an individual is thinking of something that is unrelated to the task he/she is performing.

Experience Sampling : ↑ A scientific method in which a person is asked to report their experience; that is, whether he or she is paying attention or mind wandering at random intervals in the laboratory setting or in the real world.

Electroenceph-Alogram (EEG—“elec-tro-en-sef-a-lo-gram”) : ↑ Electrical activity of many neurons in the brain that is measured by electrodes placed on the scalp.

Event-Related Potential (ERPs) : ↑ Peaks or troughs in the averaged EEG signal that reflect the brain’s responses to events we see or hear.

P300 : ↑ An ERP component that typically peaks around 300 ms (therefore “300”) after a person sees a picture or hears a sound. It reflects the brain’s processing of the information that is seen or heard. an ERP component that typically peaks around 300 ms (therefore “300”) after a person sees a picture or hears a sound. It reflects the brain’s processing of the information that is seen or heard.

Feedback Error-Related Negativity : ↑ An ERP component that reflects how much a person is monitoring the accuracy of his/her performance.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

[1] ↑ Smallwood, J., and Andrews-Hanna, J. 2013. Not all minds that wander are lost: the importance of a balanced perspective on the mind-wandering state. Front. Psychol. 4:441. doi:10.3389/fpsyg.2013.00441

[2] ↑ Smallwood, J. 2013. Distinguishing how from why the mind wanders: a process-occurrence framework for self-generated mental activity. Psychol. Bull. 139(2013):519–35. doi:10.1037/a0030010

[3] ↑ Smallwood, J., Beach, E., Schooler, J. W., and Handy, T. C. 2008. Going AWOL in the brain: mind wandering cortical analysis of external events. J. Cogn. Neurosci. 20:458–69. doi:10.1162/jocn.2008.20037

[4] ↑ Kam, J. W. Y., Dao, E., Blinn, P., Krigolson, O. E., Boyd, L. A., and Handy, T. C. 2012. Mind wandering and motor control: off-task thinking disrupts the online adjustment of behavior. Front. Hum. Neurosci. 6:329. doi:10.3389/fnhum.2012.00329

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It’s long been associated with failing grades and accidents behind the wheel, but it turns out that the wandering mind may be far more complex than many believe.

A new article by Paul Seli, a postdoctoral fellow working in the lab of Dan Schacter , the William R. Kenan Jr. Professor of Psychology, examines variations in mind wandering. In the article, Seli and colleagues argue that mind wandering happens both with and without intention, noting important differences between the two in terms of causes and consequences. The research pointing to this conclusion is outlined in a paper in Trends in Cognitive Sciences .

Researchers first began examining mind wandering — or “task-unrelated images and thoughts” — in the late 1970s. Despite a noted difference between intentional and unintentional modes, the distinction had little impact on the field and consequently fell by the wayside.

“Over the years, a number of different constructs have been unified under the single term ‘mind wandering,’ and through that process, the distinction between intentional and unintentional types was lost,” said Seli. “However, if intentional and unintentional types of mind wandering behave differently, and if their causes differ, then it would be exceptionally important to distinguish between the two. Without such a distinction, researchers will effectively conflate two unique cognitive experiences, and as a consequence, our understanding of mind wandering will be incomplete and perhaps even flawed.”

By the time Seli, as a Ph.D. student at the University of Waterloo in Canada, began to look into mind wandering, it was largely regarded as unintentional thought with links to a range of negative consequences.

Before long, though, he began to suspect something deeper was at work.

“To study mind wandering in the lab, we often present participants with boring tasks to elicit these task-unrelated thoughts,” he said. “Throughout these tasks, we typically assess mind wandering by presenting participants with ‘thought probes,’ which are temporary task interruptions that require them to report whether their thoughts are focused on the task or on something unrelated.”

Online learning: It’s different

Over the course of several experiments, Seli began to realize that some participants weren’t simply losing their focus, but seemed to intentionally disengage.

“In some cases, the participants clearly didn’t care about the task whatsoever … they were simply there for the $10 or for course credit,” he said. “So when these participants experienced mind wandering, it was likely the case that this mind wandering was initiated intentionally, rather than unintentionally.

“Now, there are certainly instances where people care about performing well on these laboratory tasks, and despite their best intentions to stay focused, their thoughts drift away, but it became clear to me that this isn’t always true, even though this is often the assumption that is made in the literature. If people do in fact frequently experience intentional mind wandering, and if the causes of intentional and unintentional mind wandering differ, then this would be exceptionally important because it would suggest that attempts to reduce the occurrence of mind wandering will also likely differ.”

Seli, working first with colleagues in Canada and then at Harvard , set about devising experiments aimed at understanding the distinction between intentional and unintentional mind wandering.

One way to demonstrate that intentional and unintentional mind wandering are distinct experiences, the researchers found, was to examine how these types of mind wandering vary depending on the demands of a task.

In one study, Seli and colleagues had participants complete a sustained-attention task that varied in terms of difficulty. Participants were instructed to press a button each time they saw certain target numbers on a screen (i.e., the digits 1-2 and 4-9) and to withhold responding to a non-target digit (i.e., the digit 3). Half of the participants completed an easy version of this task in which the numbers appeared in sequential order, and the other half completed a difficult version where the numbers appeared in a random order.

“We presented thought probes throughout the tasks to determine whether participants were mind wandering, and more critically, whether any mind wandering they did experience occurred with or without intention,” Seli said. “The idea was that, given that the easy task was sufficiently easy, people should be afforded the opportunity to intentionally disengage from the task in the service of mind wandering, which might allow them to plan future events, problem-solve, and so forth, without having their performance suffer.

“So, what we would expect to observe, and what we did in fact observe, was that participants completing the easy version of the task reported more intentional mind wandering than those completing the difficult version. Not only did this result clearly indicate that a much of the mind wandering occurring in the laboratory is engaged with intention, but it also showed that intentional and unintentional mind wandering appear to behave differently, and that their causes likely differ.”

The findings add to past research raising questions on whether mind wandering might in some cases be beneficial.

“Taking the view that mind wandering is always bad, I think, is inappropriate,” Seli said. “I think it really comes down the context that one is in. For example, if an individual finds herself in a context in which she can afford to mind-wander without incurring performance costs — for example, if she is completing a really easy task that requires little in the way of attention — then it would seem that mind wandering in such a context would actually be quite beneficial as doing so would allow the individual to entertain other, potentially important, thoughts while concurrently performing well on her more focal task.

“Also, there is research showing that taking breaks during demanding tasks can actually improve task performance, so there remains the possibility that it might be beneficial for people to intermittently deliberately disengage from their tasks, mind-wander for a bit, and then return to the task with a feeling of cognitive rejuvenation.”

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How to Tame Your Wandering Mind

Learn to take steps to deal with distraction..

Posted April 24, 2022 | Reviewed by Jessica Schrader

• Understanding Attention
• Find counselling to help with ADHD
• We can tame our mind-wandering.
• Three tips can help you use mind-wandering to your advantage.
• These include making time to mind-wander and controlling your response to it.

Researchers believe that when a task isn’t sufficiently rewarding, our brains search for something more interesting to think about.

You have a big deadline looming, and it’s time to hunker down. But every time you start working, you find that, for some reason, your mind drifts off before you can get any real work done. What gives? What is this cruel trick our brains play on us, and what do we do about it?

Thankfully, by understanding why our mind wanders and taking steps to deal with distraction, we can stay on track. But first, let’s understand the root of the problem.

Why do our minds wander?

Unintentional mind-wandering occurs when our thoughts are not tied to the task at hand. Researchers believe our minds wander when the thing we’re supposed to be doing is not sufficiently rewarding, so our brains look for something more interesting to think about.

We’ve all experienced it from time to time, but it’s important to note that some people struggle with chronic mind-wandering : Though studies estimate ADHD afflicts less than 3% of the global adult population, it can be a serious problem and may require medical intervention.

For the vast majority of people, mind-wandering is something we can tame on our own—that is, if we know what to do about it. In fact, according to Professor Ethan Kross, director of the Emotion & Self Control Laboratory at the University of Michigan and author of Chatter: The Voice in Our Head, Why It Matters, and How to Harness It , mind-wandering is perfectly normal.

“We spend between a third to a half of our waking hours not focused on the present,” he told me in an email. “Some neuroscience research refers to our tendency to mind-wander as our ‘default state.’”

So why do we do it?

“Mind-wandering serves several valuable functions. It helps us simulate and plan for the future and learn from our past, and it facilitates creative problem-solving,” Kross explained. “Mind-wandering often gets a bad rep, but it’s a psychological process that evolved to provide us with a competitive advantage. Imagine not being able to plan for the future or learn from your past mistakes.”

Is mind-wandering bad for you?

“Like any psychological tool, however, mind-wandering can be harmful if used in the wrong context (i.e., when you’re trying to focus on a task) or inappropriately (i.e., when you worry or ruminate too much),” according to Kross. In other words, mind-wandering is a problem when it becomes a distraction. A distraction is any action that pulls you away from what you planned to do.

If, for instance, you intended to work on a big project, such as writing a blog post or finishing a proposal, but instead find yourself doing something else, you’re distracted.

The good news is that we can use mind-wandering to our advantage if we follow a few simple steps:

1. Make time to mind-wander

Mind-wandering isn’t always a distraction. If we plan for it, we can turn mind-wandering into traction. Unlike a distraction , which by definition is a bad thing, a diversion is simply a refocusing of attention and isn’t always harmful.

There’s nothing wrong with deciding to refocus your attention for a while. In fact, we often enjoy all kinds of diversions and pay for the privilege.

A movie or a good book, for instance, diverts our attention away from real life for a while so we can get into the story and escape reality for a bit.

Similarly, if you make time to allow your mind to drift and explore whatever it likes, that’s a healthy diversion, not a distraction.

The first step to mastering mind-wandering is to plan time for it. Use a schedule maker and block off time in your day to let your thoughts flow freely. You’ll likely find that a few minutes spent in contemplation can help you work through unresolved issues and lead to breakthroughs. Scheduling mind-wandering also lets you relax because you know you have time to think about whatever is on your mind instead of believing you need to act on every passing thought.

It’s helpful to know that time to think is on your calendar so you don’t have to interrupt your mind-wandering process or risk getting distracted later.

2. Catch the action

One of the difficulties surrounding mind-wandering is that by the time you notice you’re doing it, you’ve already done it. It’s an unconscious process so you can’t prevent it from happening.

The good news is that while you can’t stop your mind from wandering, you can control what you do when it happens.

Many people never learn that they are not their thoughts. They believe the voice in their head is somehow a special part of them, like their soul speaking out their inner desires and true self. When random thoughts cross their mind, they think those thoughts must be speaking some important truth.

Not true. That voice in your head is not your soul talking, nor do you have to believe everything you think.

When we assign undue importance to the chatter in our heads, we risk listening to half-baked ideas, feeling shame for intrusive thoughts, or acting impulsively against our best interests.

A much healthier way to view mind-wandering is as brain static. Just as the random radio frequencies you tune through don’t reveal the inner desires of your car’s soul, the thoughts you have while mind-wandering don’t mean much—unless, that is, you act upon them.

Though it can throw us off track, mind-wandering generally only lasts a few seconds, maybe minutes. However, when we let mind-wandering turn into other distractions, such as social-media scrolling, television-channel surfing, or news-headline checking, that’s when we risk wasting hours rather than mere minutes.

If you do find yourself mentally drifting off in the middle of a task, the important thing is to not allow that to become an unintended action, and therefore a distraction.

An intrusive thought is not your fault. It can’t be controlled. What matters is how you respond to it—hence the word respon-sibility.

Do you let the thought go and stay on task? Or do you allow yourself to escape what you’re doing by letting it lead you toward an action you’ll later regret?

3. Note and refocus

Can we keep the helpful aspects of mind-wandering while doing away with the bad? For the most part, yes, we can.

According to Kross, “Mind-wandering can easily shift into dysfunctional worry and rumination. When that happens, the options are to refocus on the present or to implement tools that help people mind-wander more effectively.”

One of the best ways to harness the power of mind-wandering while doing an important task is to quickly note the thought you don’t want to lose on a piece of paper. It’s a simple tactic anyone can use but few bother to do. Note that I didn’t recommend an app or sending yourself an email. Tech tools are full of external triggers that can tempt us to just check “one quick thing,” and before we know it, we’re distracted.

Rather, a pen and Post-it note or a notepad are the ideal tools to get ideas out of your head without the temptations that may lead you away from what you planned to do.

Then, you can collect your thoughts and check back on them later during the time you’ve planned in your day to chew on your ideas. If you give your thoughts a little time, you’ll often find that those super important ideas aren’t so important after all.

If you had acted on them at the moment, they would have wasted your time. But by writing them down and revisiting them when you’ve planned to do so, they have time to marinate and may become less relevant.

However, once in a while, an idea you collected will turn out to be a gem. With the time you planned to chew on the thought, you may discover that mind-wandering spurred you to a great insight you can explore later.

By following the three steps above, you’ll be able to master mind-wandering rather than letting it become your master.

Nir Eyal, who has lectured at Stanford's Graduate School of Business and the Hasso Plattner Institute of Design, is the author of Indistractable: How to Control Your Attention and Choose Your Life.

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Mind & Body Articles & More

How mind-wandering may be good for you, new research suggests that mind-wandering can serve important functions for our performance and well-being..

When writing a song or a piece of prose, I often choose to let my mind wander, hoping the muse will strike. If it does, it not only moves my work along but feels great, too!

That’s why I was troubled by studies that found an association between mind-wandering and problems like unhappiness and depression —and even a shorter life expectancy . This research suggests that focusing one’s thoughts on the present moment is linked to well-being, while spacing out—which I personally love to do—is not.

Now, new studies are bringing nuance to this science. Whether or not mind-wandering is a negative depends on a lot of factors—like whether it’s purposeful or spontaneous, the content of your musings, and what kind of mood you are in. In some cases, a wandering mind can lead to creativity, better moods, greater productivity, and more concrete goals.

Here is what some recent research says about the upsides of a meandering mind.

Mind-wandering can make you more creative

It’s probably not a big surprise that mind-wandering augments creativity—particularly “divergent thinking,” or being able to come up with novel ideas.

In one study , researchers gave participants a creativity test called the Unusual Uses Task that asks you to dream up novel uses for an everyday item, like a paperclip or a newspaper. Between the first and second stages, participants either engaged in an undemanding task to encourage mind-wandering or a demanding task that took all of their concentration; or they were given a resting period or no rest. Those participants who engaged in mind-wandering during the undemanding task improved their performance much more than any of the other groups. Taking their focus off of the task and mind-wandering, instead, were critical to success.


“The findings reported here provide arguably the most direct evidence to date that conditions that favor mind-wandering also enhance creativity,” write the authors. In fact, they add, mind-wandering may “serve as a foundation for creative inspiration.”

As a more recent study found, mind-wandering improved people’s creativity above and beyond the positive effects of their reading ability or fluid intelligence, the general ability to solve problems or puzzles.

Mind-wandering seems to involve the default network of the brain, which is known to be active when we are not engaged directly in tasks and is also related to creativity.

So perhaps I’m right to let my focus wander while writing: It helps my mind put together information in novel and potentially compelling ways without my realizing it. It’s no wonder that my best inspirations seem to come when I’m in the shower or hiking for miles on end.

Mind-wandering can make you happier…depending on the content

The relationship between mind-wandering and mood may be more complicated than we thought.

In one study , researchers pinged participants on a regular basis to see what they were doing, whether or not their minds were wandering, and how they were feeling. As in an earlier experiment , people tended to be in a negative mood when they were mind-wandering. But when researchers examined the content of people’s thoughts during mind-wandering, they found an interesting caveat: If participants’ minds were engaged in interesting, off-task musings, their moods became more positive rather than more negative.

As the authors conclude, “Those of us who regularly find our minds in the clouds—musing about the topics that most engage us—can take solace in knowing that at least this form of mind-wandering is associated with elevated mood.”

It may be that mood affects mind-wandering more than the other way around . In a similar study , researchers concluded that feeling sad or being in a bad mood tended to lead to unhappy mind-wandering, but that mind-wandering itself didn’t lead to later bad moods. Earlier experiments may have conflated mind-wandering with rumination—an unhealthy preoccupation with past failures that is tied to depression.

“This study suggests that mind-wandering is not something that is inherently bad for our happiness,” write the authors. Instead, “Sadness is likely to lead the mind to wander and that mind-wandering is likely to be [emotionally] negative.”

A review of the research on mind-wandering came to a similar conclusion: Mind-wandering is distinct from rumination and therefore has a different relationship to mood.


Compassion Meditation

Strengthen feelings of concern for the suffering of others

Can we actually direct our mind-wandering toward more positive thoughts and away from rumination? It turns out that we can! One study found that people who engaged in compassion-focused meditation practices had more positive mind-wandering. As an added bonus, people with more positive mind-wandering were also more caring toward themselves and others, which itself is tied to happiness.

Mind-wandering may improve job performance

Taking a break from work can be a good thing—perhaps because our minds are freer to wander.

Mind-wandering is particularly useful when work is mind-numbing. In one study , participants reported on their mind-wandering during a repetitive task. Participants who engaged in more mind-wandering performed better and faster, decreasing their response times significantly. The researchers speculated that mind-wandering allowed people to go off-task briefly, reset, and see data with fresh eyes—so that they didn’t miss sudden changes.

In another study , researchers aimed to figure out what parts of the brain were implicated in mind-wandering and discovered something unexpected. When their frontal lobes were stimulated with a small electrical current to boost mind-wandering, people’s performance on an attention task slightly improved.

Of course, not every job calls for mind-wandering. A surgeon or a driver should stay focused on the task at hand, since mind-wandering could be detrimental to both . On the other hand, even for them it might be rejuvenating to take a mind-wandering break after their workday is over, leading to more focused attention the next time around.

Mind-wandering may help us with goal-setting

It seems like mind-wandering would be detrimental when it comes to planning for the future. In fact, some research suggests mind-wandering can improve goal-setting.

In a recent neuroscience experiment , participants did an undemanding task and reported on the content of their thoughts as researchers scanned their brains with fMRI. Afterwards, they wrote for 15 minutes about personal goals or TV programs (the control group). Then, they repeated these two tasks—the undemanding one and writing about goals or TV.

More on Mind-Wandering

Explore whether mind wandering makes you unhappy or less caring .

Discover how to focus a wandering mind .

Read Rick Hanson’s seven tips for paying attention .

Read a skeptical scientist’s take on the relationship between mindfulness and mind-wandering .

Analyzers unaware of the study’s purpose were asked to assess the concreteness of participants’ goal-setting and TV program descriptions. The result? People with wandering minds—who probably started musing about what they really wanted in life after the first writing session—ultimately came up with more concrete and higher-quality goal descriptions in the second session. Over the course of the experiment, their brains also showed an increase in connectivity between the hippocampus and the pre-frontal cortex—areas implicated in goal-setting.

Research has also found that, the more people engage in mind-wandering during a task, the more they are willing to wait for a reward afterwards. According to the researchers, this suggests that mind-wandering helps delay gratification and “engages processes associated with the successful management of long-term goals.”

On the other hand, some research suggests mind-wandering makes us less “gritty”—or less able to stay focused on our goals to completion—especially if it is spontaneous rather than deliberate. So, it may be important to consider where you are in the process of goal creation before deciding mind-wandering would be a good idea.

None of this suggests that mind-wandering is better for us than being focused. More likely, both aspects of cognition serve a purpose. Under the right circumstances, a wandering mind may actually benefit us and possibly those around us. The trick is to know when to set your mind free.

About the Author

Jill Suttie

Jill Suttie, Psy.D. , is Greater Good ’s former book review editor and now serves as a staff writer and contributing editor for the magazine. She received her doctorate of psychology from the University of San Francisco in 1998 and was a psychologist in private practice before coming to Greater Good .

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Solar Eclipse

Can't make it to the total eclipse 5 fun ways to bring wonder and awe into your life.

On Monday, April 8, millions of people across the U.S. will be able to view a total solar eclipse — an experience that eclipse chaser and science writer David Baron says will change your life.

"You will see a sun you've never seen before," he told Life Kit in an interview . "It's like you've left the solar system and are looking back from some other world."

But ... what if you can't make it to this awe-inducing, otherworldly, once-in-a-blue-moon solar event?

Don't worry — there are other ways to bring wonder and enchantment into your everyday life. Here are 5 tips from Life Kit's experts.

NPR will also be sharing highlights here from across the NPR Network throughout the day Monday if you're unable to get out and see it in real time.

To capture the bizarre, make sense of your dreams

Want to capture the surreality of the eclipse you can't make? Try interpreting your dreams . Deirdre Barrett, a dream researcher at Harvard, explains how. Say your intention aloud at bedtime. "Just tell yourself as you're falling asleep that you want to remember your dreams," she says.

The moment you wake up, write down your dream and "take a moment to notice what you were dreaming and think about whether it has any potential relevance in your waking life," says Barrett. Pay attention to the symbols and images. Then ask yourself what those visuals mean to you. To find out how to use your dreams to solve problems , listen to our episode.

To behold supernatural beauty, open your eyes to novelty

Yes, the total eclipse will be the most brilliant event in the heavens on Monday, but that doesn't mean you can't find beauty in the world around you . Jenny Odell, author of How to Do Nothing , explained how to do this in a 2020 interview with Life Kit.

Be attentive to change, she says. Walk through your neighborhood and "try to pay attention to things that are flowering. This is a good time to be doing that because it's spring," she says. "Maybe over the course of weeks or months, continue to pay attention to those plants and track their flowering processes." Or you might focus on the different kinds of insects flying and buzzing about, or the sounds around you.

This exercise can help reopen your eyes to enchantment and novelty in your everyday life. For more exercises on how to pay attention , listen to our episode.

To alter your perception, look at a work of art

Just like a viewing an eclipse, connecting with a piece of art that really moves you can change your life . But how do you do that?

Even though it may not be what the artist intended, let yourself draw personal connections to the art, says art historian Susie Hodge. A color, a pattern or flower in a painting, for example, "might trigger something in your childhood or the deep recesses of your memory."

These free associations will help elicit an emotional reaction when you look at a work. Let your mind wander and follow your train of thought wherever it leads you. And a deep connection "will happen," says Hodge. Read the full story to get tips on what to look for when standing in front of a work of art .

To conjure powerful emotions, connect your heart to a poet's

Witnessing something as supernatural as an eclipse can conjure powerful emotions that you may not be able to describe — but perhaps a poet can. See if you can connect feelings to words and move your heartstrings by reading poetry .

To do that, Harryette Mullen, a poet and professor at the University of California, Los Angeles, says to let go of trying to unlock the meaning of a poem as the poet intended and interpret it in your own way. Take a look at this poem, " The Song of Wandering Aengus " by William Butler Yeats. Ask yourself: What overall impression do you get? What ideas float around in your mind? What do you feel? Just look around in your own brain as you read the poem and take in what's there.

"Those kinds of overall impressions, I think most of us are left with something," says Mullen. Whatever that "something" is — trust it. Find out how to "visualize" a poem in this story.

To transform your body and mind through nature, try 'forest-bathing'

Yes, viewing a total solar eclipse can be a transformational experience — but so can other elements of nature. Like spending time in the forest, what the Japanese call shinrin-yoku . "It is simply being in nature, connecting with it through our sense of sight, hearing, taste, smell and touch," says Qing Li, a researcher on this topic and a professor at Nippon Medical School in Tokyo.

Gary Evans, director of the Forest Bathing Institute in the U.K. , explains how to connect your body and mind to nature. Find a place in a forest or park where you are surrounded by trees. Settle in a spot that feels beautiful and resonant to you.

Now sit down, says Evans, and breathe deeply. "Inhale for a count of two and exhale for a count of four. Then keep that going. When the exhale is slower than the inhale, it sends a physiological message to your body that says: 'I'm safe. I can relax. It's OK.' "

You may be surprised by what you discover, says Evans. "Depending on what's happening in your emotional world, quite often when we look at nature or the forest, it sends something back to us to help us make sense of what's going on in our life." Learn more about the science of forest bathing and how it affects mental and physical health.

The digital story was written by Malaka Gharib and edited by Clare Marie Schneider. The visual editor is Beck Harlan. We'd love to hear from you. Leave us a voicemail at 202-216-9823, or email us at [email protected].

Listen to Life Kit on Apple Podcasts and Spotify , and sign up for our newsletter .

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Mind wandering perspective on attention-deficit/hyperactivity disorder

• • Excessive, spontaneous mind wandering is associated with attention deficit hyperactivity disorder (ADHD).
• • Deficient regulation of the default mode network in ADHD might lead to this type of mind wandering.
• • This neural dysregulation might also underpin inattention and deficient cognitive performance.
• • Converging evidence draws parallels between regulatory processes of mind wandering and deficient regulation in ADHD.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder associated with a range of mental health, neurocognitive and functional problems. Although the diagnosis is based on descriptions of behaviour, individuals with ADHD characteristically describe excessive spontaneous mind wandering (MW). MW in individuals with ADHD reflects constant mental activity which lacks topic stability and content consistency. Based on this review of the neural correlates of ADHD and MW, we outline a new perspective on ADHD: the MW hypothesis. We propose that altered deactivation of the default mode network, and dysfunctional interaction with the executive control network, leads to excessive and spontaneous MW, which underpins symptoms and impairments of ADHD. We highlight that processes linked to the normal neural regulation of MW (context regulation, sensory decoupling, salience thresholds) are deficient in ADHD. MW-related measures could serve as markers of the disease process, as MW can be experimentally manipulated, as well as measured using rating scales, and experience sampling during both cognitive tasks and daily life. MW may therefore be a potential endophenotype.

1. Introduction

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder affecting 5–6% of children and 3–4% of adults worldwide ( Fayyad et al., 2007 ; Polanczyk et al., 2007 ). ADHD is characterised by developmentally inappropriate and impairing levels of inattentive, hyperactive and impulsive behaviours. The disorder is often accompanied by emotional lability ( Skirrow et al., 2009 ), cognitive performance deficits ( Banaschewski et al., 2012 ; Kofler et al., 2013 ) and mental health problems including anxiety, mood, personality and substance use disorders ( Fayyad et al., 2007 ). ADHD is further linked to detrimental outcomes including educational and occupational failure, transport accidents with increased mortality ( Kooij et al., 2010 ; Asherson et al., 2016 ) and criminal behaviour ( Lichtenstein and Larsson, 2013 ).

Despite considerable progress in understanding the symptoms and impairments of ADHD and the availability of effective treatments (NICE, 2008), key clinical issues remain to be resolved. ADHD, particularly in adults, remains a disorder that often goes undiagnosed and untreated. One explanation is diagnostic uncertainty due to the high rates of psychiatric comorbidity and overlap of ADHD symptoms with other common mental health disorders ( Asherson et al., 2016 ). The diagnosis also relies on subjective reports of symptoms and behaviours, leading to both under and over reporting of symptoms ( Barkley et al., 2002 ; Du Rietz et al., 2016 ; Faraone and Biederman, 2016 ). Another problem is that current medications provide short-term control of ADHD symptoms, but do not bring about longer-term symptom remission, or adequate control of symptoms in all cases. Further progress in diagnosis, prevention and treatment will likely require a better understanding of the underlying neural and cognitive mechanisms that lead directly to the symptoms and impairments of ADHD, and can be targeted by treatment interventions.

Here we propose a novel approach that focuses on a measurable component of ADHD psychopathology: excessive, spontaneous mind wandering (MW) ( Mowlem et al., 2016 ). We put forth a new hypothesis for ADHD (see Fig. 1 ) in which aberrant regulation within the default mode networks, and between default mode and executive control networks, leads to spontaneous MW, which in turn leads to symptoms and impairments of ADHD, and may also underlie some of the cognitive performance deficits seen in ADHD. This is an alternative to the usual model, which views measures of cognitive function, such as sustained attention and inhibitory control deficits, as intermediate endophenotypes on the pathway from genes to behaviour ( Castellanos and Tannock, 2002 ; Rommelse et al., 2008 ).

Visualisation of the linear relationship between neural activity, mind wandering (MW), inattentive symptoms and attentional lapses in the MW hypothesis. The top, central image represents the three neural networks underlying excessive and spontaneous mind wandering in ADHD. The key hubs of the default mode network are the posterior cingulate cortex, and ventromedial prefrontal cortex, associated with active mind wandering. The central executive network includes dorsolateral prefrontal cortex, and posterior parietal cortex, which are active during cognitively demanding tasks and serve as a marker of task focus. The salience network involves the anterior cingulate cortex, and anterior insula, linked to the regulation of the interaction between the default mode and central executive network. The bottom, left image represents inattentive symptoms in ADHD. The bottom, right image represents the greater variability in the distribution of reaction time scores in ADHD.

We propose this as a promising new avenue for research as MW has been linked to ADHD and ADHD-associated impairments, and unlike ADHD symptoms such as inattention, MW can be measured using a range of direct and indirect measures. These include rating scale state and trait measures, experience sampling in daily life, experience sampling during experimental paradigms, and the neural correlates of MW. Potentially these may provide new clinical and neural biomarkers of ADHD that could provide new insights into the neurobiological basis of ADHD, which can be used for diagnosis and prediction and monitoring of treatment effects, and could lead to novel treatments targeting the regulation of MW in ADHD.

2. ADHD, mind wandering and the default mode network

2.1. what is mind wandering.

Mind wandering (MW) occurs when one’s mind drifts away from the primary task and focuses on internal, task-unrelated thoughts and images. MW is a universal experience that represents up to 50% of daily thinking time ( Smallwood and Schooler, 2015 ). While some forms of MW can be beneficial to individuals (e.g. strategic thinking about a grant proposal while driving a car), other forms can be detrimental (e.g. spontaneous uncontrolled thoughts that interfere with tasks such as listening to a lecture). These two types of MW have been referred to as deliberate and spontaneous, respectively, and are thought to reflect a different balance of regulatory processes on internal self-generated thought ( Christoff et al., 2016 ; Seli et al., 2015 ). Spontaneous MW, detrimental to performance, has been proposed as a mechanism explaining many of the symptoms and impairments of ADHD ( Mowlem et al., 2016 ; Seli et al., 2015 ) believed to reflect dysfunctional connectivity between the brain’s default mode network (DMN) and executive control networks ( Fox et al., 2015 ; Sripada et al., 2014 ).

2.2. Spontaneous mind wandering is associated with ADHD

The first study of MW in ADHD was conducted using an experience sampling technique to measure on-task and off-task thoughts during a simple attention task ( Shaw and Giambra, 1993 ).The frequency of task-unrelated thoughts was found to be increased in college students with a childhood history of ADHD diagnosis, compared to controls. Among the controls, male and female groups that reported high levels of childhood ADHD symptoms also demonstrated more task-unrelated thoughts than controls reporting low levels of childhood ADHD symptoms.

A further study, using the MW Deliberate and Spontaneous scales ( Carriere et al., 2013 ) found that a group who had been diagnosed with ADHD showed more spontaneous than deliberate MW ( Seli et al., 2015 ). They further showed that spontaneous MW (but not deliberate MW) was significantly correlated with ADHD symptom severity. In another study using an adult community sample, a composite index of ADHD symptoms was positively correlated with a composite index of MW derived from experience sampling data of task-unrelated thoughts during a lab session, and daily life ( Franklin et al., 2017 ). Furthermore, ADHD symptoms were related to MW episodes that were detrimental to the task at hand, and a sub-clinical group with high ADHD symptom scores had disruptive MW episodes that impaired daily-life function. ADHD symptomatology was also positively correlated with a lack of awareness of engaging in MW. In this study, lacking awareness of MW mediated between ADHD symptoms and impairment, suggesting that increasing awareness of MW in ADHD might lead to functional improvements ( Franklin et al., 2017 ).

In our own studies, we developed a clinical scale reflecting ADHD patient reports of excessive spontaneous MW ( Mowlem et al., 2016 ). The 12-item Mind Excessively Wandering Scale (MEWS) captures three characteristics of MW in ADHD: thoughts constantly on the go, thoughts flitting from one topic to another, and multiple thoughts at the same time. Exploratory factor analysis found the 12-item MEWS to be unidimensional, with a single factor explaining 70% of the variance ( Mowlem et al., 2016 ). Two independent samples revealed significantly elevated ratings of MW in ADHD, and that MW successfully discriminated between cases and controls to a similar extent as rating scale measures of DSM-IV ADHD symptoms (sensitivity and specificity around 0.90 in both studies). MEWS scores were also correlated strongly and positively with measures of inattention (r = .77), hyperactivity/impulsivity (r = .69) and ADHD-related impairment (r = 0.81). Furthermore, repeated analysis over a 6-month period showed moderate to high covariation of change in MEWS scores with change in inattention (r = .53), hyperactivity/impulsivity (r = .31) and impairment (r = .62). Regarding impairment, MEWS scores were the strongest predictor of functional impairment, followed by inattention and hyperactivity/impulsivity, indicating the clinical relevance of MW as a predictor of impairment in daily life.

Overall, these findings suggest that asking about the subjective experience of MW alone, provides a better prediction of ADHD associated impairment than the traditional ADHD inattention and hyperactive/impulsive symptoms. Moreover, as we will discuss, MW may reflect the primary deficit arising directly from dysregulated neural network activity in ADHD that underpins the symptoms and impairments currently used to define ADHD.

2.3. Mind wandering and the default mode network

The neural basis of MW has generated considerable interest since 2006 ( Callard et al., 2013 ). The DMN has been implicated as a potential source of self-generated thoughts unrelated to external goal-directed tasks. The DMN reflects a network of interacting brain regions (i.e. medial prefrontal cortex, posterior cingulate cortex and medial temporal regions) which show correlated neural activation, most active during the resting state, when the person is awake but in a daydreaming or MW state. The network can be conceptualised as switching off during external goal-directed tasks, and switching on when there are internal self-generated thoughts ( Buckner and Vincent, 2007 ).

Among the first investigations of MW-associated neural activity were two functional magnetic resonance imaging (fMRI) studies using tasks with low cognitive demand ( McKiernan et al., 2006 ), or highly practiced cognitive tasks ( Mason et al., 2007 ), during which episodes of MW were frequent. These studies found a strong correlation between the reduced deactivation of the DMN during on-task conditions and frequency of subjectively-reported MW. The MW-associated neural activity patterns were in stark contrast with those seen during novel or high cognitive demand conditions, when MW was less frequent. McKiernan et al. (2006) conducted three different cognitive tasks under three levels of task difficulty, making a total of nine different task/difficulty conditions, each associated with a different frequency of task-unrelated thoughts. They reported that 81% of the variance in the frequency of task-unrelated thoughts was explained by task-induced deactivation of the DMN, which is remarkably high for an association between a direct measure of brain function using fMRI, and subjective reports of a mental phenomenon. Similarly, Mason et al. (2007) found activation in DMN regions during episodes of MW, including the precuneus.

A limitation of these early studies was that the frequency of task-unrelated thoughts was measured outside the scanning sessions. To provide a more direct investigation of neural activity during periods of MW, Christoff et al. (2009) used in-scanner experience-sampling probes to identify periods of task-related and task-unrelated thoughts during a sustained attention task. The experience-sampling probes asked two questions: “Where was your attention focused just before the probe – on task or off task?”, and “How aware were you of where your attention was focused – aware or unaware?”. The strongest activation was seen in two normally anti-correlated networks (default mode and executive control networks) during MW episodes, and even stronger during “unaware” compared to “aware” MW.

The finding of co-activation of both executive and default networks during periods of task-unrelated thoughts in control subjects was subsequently confirmed by meta-analysis of fMRI studies ( Fox et al., 2015 ). Examining 24 functional neuroimaging studies of spontaneous thought processes, meta-analysis using activation likelihood estimation (ALE) found that both DMN regions (medial prefrontal cortex, posterior cingulate cortex, medial temporal lobe, bilateral inferior parietal lobule), and non-DMN regions (rostrolateral prefrontal cortex, dorsal anterior cingulate cortex, insula, temporopolar cortex, secondary somatosensory cortex, and lingual gyrus) were consistently recruited during periods of spontaneous thoughts. They concluded that in addition to DMN activity, fronto-parietal network (FPN) and other non-DMN regions also played a central role in the neuroscience of MW and other forms of spontaneous thoughts.

However, not all studies have reported co-activation of DMN and executive control regions during periods of MW. Andrews-Hanna et al. (2010) introduced longer delays between stimuli. These delays induced MW which was most strongly correlated with DMN hubs rather than co-activation of both DMN and executive control networks. Likewise, in another study, task-unrelated thoughts were associated with the highest level of DMN (medial prefrontal cortex) activation compared to intermediate levels of activation for external distraction and task-related inferences, and the lowest DMN activity during periods of on-task thoughts ( Stawarczyk et al., 2011a ). Further evidence comes from studies focusing on the role of executive control mechanisms in MW.

2.4. Mind wandering and executive control

Overall the findings discussed above confirm the association of DMN activity with the frequency of task-unrelated thoughts. However, the role of executive control networks may depend on task conditions or type of MW and other forms of spontaneous thought. Typically, executive control and DMN function in an anti-correlated manner. Early work showed increased activation in executive control and decreased activation in DMN regions with increasing attentional demands, and vice versa ( Fox et al., 2005 ). Likewise, attenuated DMN activity during periods of on-task was linked with poor adjustment to attentional demands, or attentional lapses ( Weissman et al., 2006 ). Therefore, task-unrelated thoughts are expected to be associated with anti-correlation (or reduced co-activation) between executive control and DMN regions.

However, as discussed, fMRI research has been inconclusive on the role of executive control on MW, which sparked off a debate. One argument is that MW results from a failure in executive control to prevent automatic task-unrelated thoughts from becoming conscious ( McVay and Kane, 2012 ). For example, the emergence and increased frequency of MW under high demand conditions is associated with deficits in executive control, including working memory capacity and response inhibition ( McVay and Kane, 2012 ). An opposing argument states that executive control is required to maintain personally salient task-unrelated thoughts (i.e. strategic/deliberate MW) during low cognitive demand conditions, and is associated with reduced MW under high cognitive demand conditions to prevent performance decrements ( Smallwood, 2010 ; Smallwood and Schooler, 2006 ). In line with this view, MW increased linearly with time-on-task in low demand vigilance paradigms ( Randall et al., 2014 ; Thomson et al., 2015 ) and is more frequent in practiced compared to novel tasks ( Mason et al., 2007 ).

To investigate the relative role of different neural networks, an activation likelihood estimation (ALE) meta-analysis was conducted on different types of internal thoughts, including experimentally directed episodic future thinking, and spontaneous MW ( Stawarczyk and D’argembeau, 2015 ). The results showed that while these domains of internal thought activated a common set of brain regions within the default network (e.g. medial prefrontal cortex); regions supporting executive control processes (e.g. dorsolateral prefrontal cortex) were also recruited to a lesser extent during undirected MW than during directed episodic future thinking. Thus, different types of internally generated thoughts may recruit varying levels of executive control.

To address the various findings, recent models of MW better reflect the complexity of internally generated thoughts. They clarify that MW is not a unitary construct, but rather an umbrella term that captures different types of MW experiences in the general population. A key conceptual paper proposes a dynamic framework in which MW is understood as a subtype of spontaneous-thought phenomena that also includes creative thought and daydreaming ( Christoff et al., 2016 ). The authors propose a dimension of deliberate constraints related to executive control activity, with unconstrained daydreaming at one end, and constrained goal-directed thought at the other. Creative thought is proposed to reflect a more constrained form of spontaneous thought that is under greater executive control than daydreaming or MW, but less than goal-directed thoughts. They further propose a second dimension of automatic constraints on content of thought, which is weakest for common forms of daydreaming, and strongest for mental phenomenon such as ruminations and obsessions. Christoff et al. (2016) proposed that under their model, ADHD would be reflected by a problem with excessive variability in thought movement, with low deliberate constraints (excessive MW and dream-like thoughts) and low automatic constraints (thoughts that flit from one topic to another).

2.5. ADHD is associated with deficient regulation of DMN activity

Resting state connectivity studies of ADHD in children and adults have examined interactions between the DMN and executive control network, as well as connectivity within the DMN itself. These studies consistently find that anti-correlation between the executive control (fronto-parietal) network and DMN is attenuated, and that resting state connectivity within the DMN itself is reduced ( Posner et al., 2014 ). ADHD is associated with hyperactivation (deficient deactivation) of the DMN in task compared to resting state conditions ( Fassbender et al., 2009 ; Helps et al., 2010 ; Liddle et al., 2011 ; Peterson et al., 2009 ).

The observation of DMN abnormalities in ADHD led to a hypothesis known as the DMN interference model ( Sonuga-Barke and Castellanos, 2007 ). This model proposed that increased very low frequency oscillations (0.01 - 0.1 Hz) and synchronization within the DMN, which usually attenuate during goal-directed tasks, persist and interfere with task-specific neural processes, leading to lapses in attention and performance deficits ( Sonuga-Barke and Castellanos, 2007 ). Reduced DMN deactivation from rest to task, and suppressed DMN activity (up-regulation) at the transition to rest conditions, suggest inadequate neural switching in response to changes in context in ADHD compared to controls ( Liddle et al., 2011 ; Sidlauskaite et al., 2016 ). Consistent with this hypothesis, Liddle et al. (2011) found that failure to deactivate DMN regions during a low-salient (slow, boring, unrewarded) inhibition task requiring sustained attention, was reversed by methylphenidate in children with ADHD. In a further study both improvement of inattentive symptoms and normalisation of very low electroencephalography (EEG) frequencies as well as omission errors followed the use of methylphenidate ( Cooper et al., 2014 ).

Related to the default mode interference hypothesis, it has also been proposed that activation of DMN hubs will depend on motivation, cognitive load, attentional demands and individual state regulation/capacity ( Stawarczyk et al., 2011a ). This is in line with the cognitive-energetic model which proposes that the efficiency of task performance in ADHD is determined by the interplay of basic cognitive processes (e.g. stimulus encoding, memory search, binary decision and motor preparation), and the availability of these processes related to arousal and activation levels and is further modulated by interplay with executive control functions ( Sergeant, 2005 ). Both the DMN interference and cognitive-energetic models point to an inability to adapt neural network activity to changing task demands.

The DMN interference hypothesis also proposed that a certain threshold of DMN activity needs to be reached before DMN interference occurs ( Sonuga-Barke and Castellanos, 2007 ). In relation to our model of MW in ADHD, we propose that this critical threshold of DMN activity is linked to excessive spontaneous MW, which leads to the inattentive symptoms of ADHD and detrimental effects on daily-life function. Cognitive performance deficits associated with ADHD may be a direct result of internal distractibility secondary to excessive MW, or may be secondary to the direct effects of high default mode activity interfering with task-dependent neural functions. We further propose that this critical threshold of DMN activity may not be reached when there is a continuous co-activation of DMN and executive control regions associated with deliberate/strategic forms of MW. For example, individuals without a clinical diagnosis of ADHD may more readily co-activate DMN and executive control regions, and engage in deliberate rather than uncontrolled/excessive forms of spontaneous MW. Previous authors have also proposed that reduced deactivation of the DMN during task performance may explain MW and interference with task positive processes, leading to the symptoms and impairments of ADHD ( Liddle et al., 2011 ; Mowlem et al., 2016 ; Posner et al., 2014 ). However, at the time of writing this has yet to be formally evaluated.

3. A comparative analysis of ADHD and mind wandering

So far, we have outlined studies that link ADHD to MW, MW to DMN activity, and DMN activity to ADHD. These studies raise the possibility that deficient regulation of DMN activity leads to excessive spontaneous MW in individuals with ADHD, which might underpin the inattentive symptoms of ADHD and deficits in cognitive task performance. Further support for this hypothesis comes from several observations that draw parallels between processes that underlie the regulation of MW in neurotypical controls, and processes found to be deficient in ADHD. These parallels include: (1) context regulation of MW in controls, and deficient context regulation of neural activity in ADHD; (2) perceptual decoupling of somatosensory processing during MW, and in ADHD; (3) sensitivity of MW and MW-associated neural processes to task salience and rewards; (4) impairments in cognitive task performance, and function in daily life. Below we outline these areas in more detail.

3.1. Context regulation of mind wandering

The context regulation hypothesis states that an adequate capacity to self-regulate mind wandering within a context will reduce a potential negative impact on the primary task performance ( Smallwood and Andrews-Hanna, 2013 ). Context regulation of MW is characterized by adaptation of neural processes and frequency of MW to changing task demands. In community samples, MW frequency is higher during low perceptual and low cognitive demand conditions ( Filler and Giambra, 1973 ; Giambra and Grodsky, 1989 ) and lower under more cognitively demanding conditions, such as tasks with high working memory demands ( Antrobus et al., 1966 ). As discussed above Mason et al. (2007) manipulated the frequency of MW by varying task cognitive-demands, and correlated MW frequency with DMN task induced deactivations. Similar findings have been replicated by others ( Forster and Lavie, 2009 ; Levinson et al., 2012 ; McVay and Kane, 2012 ; Metcalfe and Xu, 2016 ; Ruby et al., 2013 ; Rummel and Boywitt, 2014 ; Smallwood et al., 2007 ; Xu and Metcalfe, 2016 ). Related to these findings, shifts from task-related to task-unrelated thoughts are observed during low cognitive demand tasks ( Stawarczyk et al., 2011b ; Thomson et al., 2014 ).

Regarding the potential role of executive control and working memory capacity, individuals with both low and high working memory capacity report greater levels of MW under low cognitive demand conditions ( Kane et al., 2007 ). However, under high demand conditions, task-unrelated thoughts are greater in individuals with low working memory capacity, compared to those with higher working memory capacity ( Kam and Handy, 2014 ; Kane et al., 2007 ; Unsworth and Robison, 2016 ). This effect is consistent with the role of executive control in the appropriate regulation of MW during cognitively demanding tasks.

Furthermore, higher working memory capacity predicted greater frequency of task-unrelated thoughts in a low demand breath-awareness task ( Levinson et al., 2012 ) but fewer errors (regarded as a behavioural index of less frequent MW) in a high demand 3-back working memory task ( Rummel and Boywitt, 2014 ). Similarly, the level of linguistic expertise (reflecting executive control and working memory capacity) determined the frequency of MW since individuals with high levels of linguistic ability showed more frequent task-unrelated thoughts for easy items, compared to individuals with low to medium linguistic ability ( Xu and Metcalfe, 2016 ). Thus, both working memory capacity and linguistic capacity had a moderating effect on the level of MW under low and high demand conditions.

In summary, these findings indicate that higher working memory/executive control capacity moderate frequency of MW according to task demands. In general, greater working memory capacity is predictive of more MW during low demand conditions, whereas it is predictive of less MW during high demand conditions.

3.2. Context regulation in ADHD

Context regulation of MW in ADHD has yet to be investigated. However, there is consistent evidence for deficient neural adaptation to task demands in ADHD compared to controls, with deficient upregulation of executive control regions, accompanied by deficient deactivation of the DMN. Thus, the neural networks that show deficient context regulation in ADHD are the same networks associated with context regulation of MW in neurotypical controls.

For example, deficient context regulation was seen in ADHD compared to controls using electroencephalography EEG recordings during the Flanker Task. This task contrasts a low cognitive demand (no conflict) with a high cognitive demand (conflict) condition. In contrast to the ADHD group, controls showed a significantly greater increase in frontocentral theta amplitude and decreased phase variability (which correlated with less reaction time variability, RTV) in response to the higher cognitive demands of the conflict condition ( McLoughlin et al., 2009 , 2014 ). Low phase variability over trials is thought to reflect an adaptive mechanism to maintain stable neural processing of a stimulus ( Makeig et al., 2004 ; Papenberg et al., 2013 ). Therefore, the relationship between increased theta phase variability and RTV in ADHD points to a reduced ability to maintain efficient neural adaptation and cognitive performance over trials with increasing cognitive demands.

Similarly, there was greater RTV in ADHD compared to controls, under high demand (very fast or very slow event rates), compared to low demand (medium event rates) conditions ( Metin et al., 2016 ) reflecting deficient behavioural adaptation of task performance to changing task demands. Deficient context regulation of neural (EEG) activity in ADHD is also seen in the transition from rest to task conditions ( Rommel et al., 2016 ; Skirrow et al., 2015 ); a finding that was reversed in response to methylphenidate ( Skirrow et al., 2015 ).

fMRI studies also demonstrate deficient context regulation in ADHD. Compared to controls, ADHD is associated with under-activation of the FPN (left dorsolateral prefrontal cortex) during on-task conditions ( Castellanos and Proal, 2012 ; Cortese et al., 2012 ) and reduced deactivation of the DMN (medial prefrontal cortex) when transitioning from rest to task ( Valera et al., 2010 ). Attenuated deactivation and hyperactivation within the DMN in ADHD compared to controls was also observed with time-on-task during a sustained attention task, in response to high working memory load, and with longer inter-stimulus delays ( Christakou et al., 2013 ; Liddle et al., 2011 ; Metin et al., 2015 ; Paloyelis et al., 2007 ; van Rooij et al., 2015 ).

Taken together, the evidence from cognitive-EEG and fMRI studies points to a reduced ability to modulate task positive and negative neural processes in ADHD. Since the networks involved are the same as those linked to context regulation in neurotypical controls, deficient context regulation in individuals with ADHD may explain the high frequency of task-unrelated thoughts. This hypothesis has yet to be formally tested.

3.3. Perceptual decoupling in mind wandering

A key characteristic of MW is the association with attenuated somatosensory processing, referred to as perceptual decoupling. This means that during periods of MW there is a reduced somatosensory response to sensory stimuli ( Schooler et al., 2011 ; Smallwood et al., 2013 ). One hypothesis is that perceptual decoupling explains the co-activation of the FPN and DMN, during low demand conditions; reflecting active executive control over attention to disengage from perceptual input, so as to enable mental processing of personal goals ( Smallwood et al., 2012 ). In line with this, MW has been linked to anti-correlation and lack of synchronisation between sensory cortices and DMN ( Christoff, 2012 ; Kirschner et al., 2012 ) and a positive correlation between sensory cortices and FPN hubs during on-task conditions. A novel concept suggests that the depth of perceptual decoupling might be able to distinguish between spontaneous and deliberate MW ( Seli et al., 2015 ).

EEG research has consistently reported that event-related potential (ERP) components (P1), markers of early visual information processing within 100 ms, are attenuated during periods of task-unrelated compared to task-related thoughts ( Baird et al., 2014 ; Broadway et al., 2015 ; Kam and Handy, 2014 ). Phase-locking factor analyses reflect phase synchrony of a particular frequency at a particular time across multiple trials of an event ( Tallon-Baudry et al., 1996 ). Episodes of MW were further linked to a lower phase-locking factor in theta within 50–150 ms following a visual stimulus reflecting a neural state of perceptual decoupling during MW ( Baird et al., 2014 ).

Cortical source activity analyses during a visual Sustained Attention to Response Task (SART) also confirm the attenuation of early visual information processing, during periods of MW ( Kirschner et al., 2012 ). In this study, there was also deficient intra-regional (occipital cortex) and inter-regional (visual cortex and right medial temporal lobe) connectivity when attention was focused on internal thoughts ( Kirschner et al., 2012 ). In contrast, during periods when the participants were focused on the visual task, there was greater inter-regional connectivity between the visual cortex and task-positive regions including the anterior/posterior cingulate, orbitofrontal cortex and posterior parietal gyrus. Similarly, MW was linked to both an increase in occipital and parieto-central theta and fronto-central delta power and a decrease in occipital alpha and frontal lateral beta power ( Braboszcz and Delorme, 2011 ).

Collectively, these findings suggest a switch from active cognitive processing to MW, which is facilitated by a state of perceptual decoupling, or detachment of perception from attention. Consequently, a reduced P1 amplitude is regarded as a marker of perceptual decoupling during episodes of MW.

3.4. Perceptual decoupling in ADHD

Somatosensory responses are far less studied in ADHD, and the association between sensory decoupling and ADHD is not well established. Furthermore, there have been no studies that directly investigate the relationship of perceptual decoupling to periods of MW in ADHD. Yet, the few studies that have focused on early sensory processing in ADHD find deficits that are similar to those seen during periods of MW in neurotypical controls.

Initial reports found decreased slow frequency fluctuations within the left sensorimotor cortex ( Yu-Feng et al., 2007 ) and suppression of visual ERP amplitudes during cognitive-performance tasks in children with ADHD compared to controls ( Steger et al., 2000 ). Using magnetoencephalography (MEG), adults with ADHD showed reduced event-related desynchronization in the alpha band, and synchronisation in the beta bands, in primary and secondary somatosensory cortices in response to median nerve stimulation ( Dockstader et al., 2008 ). A similar attenuated cortical sensory response was found in children with ADHD, which improved following successful treatment with methylphenidate ( Lee et al., 2005 ).

Using ERP, a larger P1 (100 ms post-stimulus) amplitude has been seen in children with ADHD compared to controls; a finding that was interpreted as a compensatory mechanism in the absence of performance differences ( Kóbor et al., 2015 ; Shahaf et al., 2012 ). In contrast, when children with ADHD made more omission errors than controls, P1 amplitude was significantly reduced ( Nazari et al., 2010 ). At the time of writing, preliminary findings from our group support this result. Using the SART, we found a reduced P1 amplitude in 33 adults with ADHD compared to 30 controls (p < 0.02), which was associated with trait measures of inattention, and MW measured using the MEWS as a state measure of excessive MW in ADHD (Bozhilova et al., unpublished data). We further found that in the ADHD cases there was a reduced P1 amplitude prior to errors compared to correct responses (p < 0.001). Under the assumption that MW will be higher prior to error than non-error responses, these findings suggest that somatosensory processing deficits could be linked to excessive MW in ADHD. This hypothesis has yet to be formally tested.

3.5. The effects of salience and reward on mind wandering

Several studies find that the frequency of MW is related to task salience or incentives designed to increase motivation. This is not surprising, since almost everyone finds it easier to remain focused on tasks that are inherently interesting, compared to mundane or boring tasks. A high degree of task-related motivation and interest were both associated with lower frequency of MW during the SART ( Seli et al., 2015 , 2016 ) as well as better information retention on a film comprehension task ( Kopp et al., 2016 ).

A related phenomenon is the response to unexpected infrequent stimuli, which tend to be of high salience in auditory oddball paradigms. Infrequent and deviant auditory stimuli were associated with an increased mismatch negativity amplitude, which is a marker of attention allocation to these stimuli, during episodes of task focus compared to a decreased amplitude during MW ( Braboszcz and Delorme, 2011 ). Therefore, MW is linked to poorer attentional engagement with task-salient stimuli. An automatic, momentary coupling of attention and perception for visually salient stimuli (coloured no-go targets) during MW, also occurred in a variation of the Go/No-Go task ( Smallwood, 2013 ) again suggesting switch away from MW.

In another study, monetary incentives increased the number of reports of self-caught MW compared to conditions that were unrewarded ( Zedelius et al., 2015 ). The incentive for accuracy of MW self-report was associated with less probe-caught MW in the absence of greater overall MW ( Zedelius et al., 2015 ). This last finding indicates that reward is likely to increase awareness of MW. Overall, these findings suggest that the effects of task salience and reward have the potential to reduce MW and MW-associated neural activity.

3.6. The effects of salience and reward on ADHD

There are numerous examples of enhanced sensitivity to the effects of task salience and rewards in children and adults with ADHD. Here we discuss some of the most pertinent studies related to MW-associated task performance and neural activity.

In a key fMRI investigation, a sample of children with ADHD and controls completed a Go/No-go task under low- and high-incentive conditions ( Liddle et al., 2011 ). In the low-incentive condition (with low rewards linked to task performance), there was attenuated DMN deactivation in the ADHD group compared to controls. When higher rewards were introduced to increase the salience of the task, DMN deactivation normalised to the same level as controls. Methylphenidate was also found to have the same effect on DMN deactivation in the ADHD group, as increasing the salience of the task through rewards. The authors concluded that both methylphenidate and enhanced salience normalised DMN deactivation and suggested that this had an impact on inattention.

In a series of publications from Kuntsi and colleagues, fast-rewarded (high incentive) conditions compared to slow-unrewarded (low incentive) conditions on tasks requiring sustained attention reduced or abolished ADHD case-control differences for arousal measures using skin conductance ( James et al., 2016 ), RTV ( Andreou et al., 2007 ; Cheung et al., 2017 ; Kuntsi et al., 2009 ; Tye et al., 2016 ) and omission errors ( Uebel et al., 2010 ), but not commission errors ( Kuntsi et al., 2009 ).

Based on the findings that enhancing task saliency alters neural responses, task performance and frequency of MW, we hypothesise that adequate rewards will modulate the frequency of MW in both neurotypical and ADHD populations. In particular, a decrease in MW will lead to better early attentional orienting in ADHD, or successful detection of visual information early on at presentation. Despite similar effects on DMN activity of task saliency (reward) and stimulants in ADHD ( Liddle et al., 2011 ), different mechanisms could be involved. For instance, rewards may moderate the degree of early visual information detection via interactions between the DMN and visual cortex. In contrast, stimulants might lead to changes in MW by altering interactions between large-scale networks: for example, FPN and DMN; DMN and ventral attention network; and DMN and the salience network. Providing both reward and stimulants reduce the frequency of MW and/or facilitate a more controlled form of MW, a combination of both might further enhance treatment effects. Further research is needed to investigate the effects of reward and stimulants on MW in ADHD and mechanisms involved in both ADHD and controls.

3.7. Cognitive performance and daily life impairments associated with mind wandering

MW has an adverse impact on both cognitive task performance and daily life in control populations. Measured performance deficits associated with MW include greater stimuli-response error rates ( Forster and Lavie, 2009 ; Stawarczyk et al., 2011b ), slower reaction times ( Smallwood et al., 2013 ; Stawarczyk et al., 2011b ) reduced accuracy of response ( Kam and Handy, 2014 ; McVay and Kane, 2009 ; Rummel and Boywitt, 2014 ; Smallwood et al., 2008 ; Thomson et al., 2014 ; Unsworth and Robison, 2016 ; Xu and Metcalfe, 2016 ) and greater mean error percentage ( Thomson et al., 2015 ).

Similarly, attenuation in the amplitude of ERPs reflecting late cognitive analysis of stimuli (e.g. attentional resource allocation, response execution/preparation and attentional orienting) has been observed during periods of MW. Examples include reduced N400, mismatch negativity ( Braboszcz and Delorme, 2011 ) and P3 amplitudes ( Barron et al., 2011 ; Riby et al., 2008 ; Smallwood et al., 2007 ; Villena-González et al., 2016 ) as well as greater central negativity (N2) ( Riby et al., 2008 ). Further, frequent MW and poorer effort were related to poorer accuracy ( Brown and Harkins, 2016 ; Seli et al., 2016 ).

MW has also been associated with several daily life impairments, including deficits in reading comprehension ( Mooneyham and Schooler, 2013 ), negative mood ( Smallwood et al., 2009a , b ; Smallwood and O’Connor, 2011 ), poorer learning ( Metcalfe and Xu, 2016 ; Xu and Metcalfe, 2016 ), higher number of car accidents ( Galéra et al., 2012 ) less cautious driving ( Yanko and Spalek, 2013 ), poorer academic performance, life-satisfaction, self-esteem and greater stress ( Mrazek et al., 2013 ).

3.8. Cognitive performance and daily life impairments associated with ADHD

Similar impairments in cognitive task performance and daily life associated with MW are also seen in ADHD. Examples include attentional orienting, performance monitoring, response preparation and inhibitory processes; manifesting in increased error rates, reaction time variability and attenuation in Cue-P3 and No-Go N2 and P3 amplitudes ( Albrecht et al., 2014 ; Cheung et al., 2017 ; McLoughlin et al., 2009 , 2010 ; Michelini et al., 2016a ; Tye et al., 2014 ; Uebel et al., 2010 ).

ADHD is also associated with impairments in daily life including poorer psychosocial, educational and global function ( Asherson et al., 2012 ; Pitts et al., 2015 ). Individuals with ADHD compared to controls are more prone to car accidents ( Vaa, 2014 ), academic underachievement ( Fischer et al., 1990 ; Weyandt and DuPaul, 2008 ), reading comprehension difficulties ( Ghelani et al., 2004 ; Miller et al., 2013 ; Stern and Shalev, 2013 ) and low self-esteem ( Shaw-Zirt et al., 2005 ).

In summary, the findings on impairment show that both ADHD and MW in non-ADHD controls appear to be linked to similar performance deficits. This is consistent with our MW hypothesis for ADHD since we propose that episodes of MW in controls and excessive spontaneous MW in individuals with ADHD lead to similar functional and cognitive impairments. Potentially, excessive spontaneous MW in ADHD can be expected to lead to typical impairments experienced by people with ADHD in their daily lives. Examples could include problems following a conversation, reading and watching a film; maintaining a coherent train of thought for problem solving and holding thoughts in mind; difficulties falling asleep due to constant mental restlessness associated with excessive MW; and feeling exhausted by the mental effort required to sustain focus on daily activities. Further research is required to investigate the extent to which impairment seen in individuals with ADHD can be explained by excessive, spontaneous MW.

3.9. Identifying causal processes

As discussed extensively in this review, deficient deactivation of the DMN during cognitive task performance has been consistently reported in ADHD. However, ADHD is associated with a wide range of cognitive and neural deficits, anyone of which could be contributing to the generation of ADHD symptoms, and be potential targets for treatment. Indeed, the range of deficits associated with ADHD has led many to argue that the neuropathological basis for ADHD is highly heterogeneous ( Coghill et al., 2005 ; Faraone, 2015 ).

Key additional processes highlighted in the literature include: deficits in the dorsal attention network of dorsolateral prefrontal cortex, basal ganglia and parietal regions during tasks of selective and sustained attention ( Hart et al., 2013 ); inhibitory control deficits supported by fMRI studies of reduced activation in key regions of inhibitory control ( Plichta and Scheres, 2014 ). Furthermore stimulants, the first line treatment for ADHD, has been shown to have effects on several of these processes ( Rubia et al., 2014 , 2009 ; Smith et al., 2013 ).

Despite the findings linking various neural functions to ADHD, it remains unclear which of these play a direct causal role in the generation of the inattentive and hyperactive/impulsive symptoms currently used to define ADHD. This is a critical point, because numerous non-causal associations are expected to arise through the process of pleiotropy, in which shared genetic (and environmental) risks can lead to multiple different phenotypic outcomes at the level of brain structure, function, cognitive performance and behaviour. Yet, only a subset of the associated neural deficits may reflect underlying causal processes in ADHD ( Kendler and Neale, 2010 ). There are several approaches that can be used to address this problem ( Kendler and Neale, 2010 ), including conducting mediation analyses with experimental trial data, or longitudinal outcome data, or taking advantage of genetic data to test for causal associations using Mendelian randomisation ( Sheehan et al., 2011 ).

3.10. Remission and persistence of ADHD

In relation to ADHD, important new insights have come from longitudinal outcome studies that investigate the cognitive and neural correlates of remission and persistence in ADHD (Franke, 2015). A central question in causal models of ADHD has been the separation of executive control measures (e.g. inhibition and working memory) from preparation-vigilance measures. Earlier work showed that measures reflecting these processes are both associated with ADHD in children, but are genetically largely uncorrelated, reflecting distinct aetiological pathways ( Kuntsi et al., 2010 , Kuntsi et al., 2014 ).

Regarding developmental change, in a 6-year longitudinal outcome study of children with DSM-IV ADHD, adolescents and young adults who no longer met ADHD criterial (ADHD remitters), but not those who still had ADHD (ADHD persisters), showed a similar profile to controls without ADHD on cognitive and neural measures. These measures indicated response preparation, attention and vigilance processes (RTV, omission errors, delta activity, errors in low-conflict conditions and contingent negative variation) and were significantly correlated to the severity of inattention at outcome. In contrast, executive control measures of working memory, and inhibitory processes did not distinguish in persisters and remitters, and did not correlate with ADHD symptoms at outcome; including commission errors, digit span backwards, and ERP activity of inhibitory control (No-go P3) and conflict monitoring (N2) ( Cheung et al., 2016 ; Michelini et al., 2016b ).

Similarly, in another follow-up study there was no an association between ADHD remission and improvements in executive functioning ( Biederman et al., 2009 ), interference control ( Pazvantoğlu et al., 2012 ), and response inhibition ( McAuley et al., 2014 ). Working memory impairments (e.g. reduced caudate activation) in young adults diagnosed with ADHD in adolescence compared to controls have also been observed regardless of whether they still met an ADHD diagnosis ( Roman-Urrestarazu et al., 2016 ).

A recent study reported increased resting-state fMRI connectivity in ADHD remitters compared to controls in the executive control network, with intermediate connectivity profiles in persisters ( Francx et al., 2015 ). Two other connectivity studies ( Michelini et al., 2017 ; Mattfeld et al., 2014 ) also indicated that connectivity within the executive control network or during executive tasks may not distinguish between ADHD persisters and remitters. Both persisters and remitters showed an increased EEG connectivity during executive control ( Michelini et al., 2017 ) and reduced negative functional correlation between medial (DMN hub) and dorsolateral prefrontal cortex (FPN hub) during resting state fMRI ( Mattfeld et al., 2014 ).

However, in a resting study fMRI, only ADHD persisters showed reduced positive functional correlation between DMN hubs (posterior cingulate and medial prefrontal cortices) ( Mattfeld et al., 2014 ). Reduced posterior cingulate cortex and medial prefrontal cortex connectivity (i.e. DMN intra-connectivity) may therefore be a neurobiological marker of persistence of ADHD ( Uchida et al., 2015 ).

From these findings we conclude that, potentially, DMN activity and preparation-vigilance processes (associated with MW) may have direct aetiological significance in ADHD since they track the symptoms of ADHD during child to adult development. In contrast, deficits in executive control functions appear to dissociate from the clinical course of ADHD symptoms during development and are therefore less likely to play a direct causal role in the ongoing generation of symptoms. Since, the neural processes tracking the clinical disorder are closely aligned to those thought to underpin MW, we propose that targeting the regulation of MW or MW-associated neural dysfunctions could potentially lead to reductions in ADHD symptoms and remission of the disorder.

4. Developmental perspective on mind wandering in ADHD

4.1. mind wandering and typical development of functional networks.

Finally, we provide a developmental perspective on the neural processes linked to MW, since the frequency and impact of MW may vary throughout development. “Small-world” properties represent quantifiable metrics of topographic properties of large-scale/global brain organisation ( Achard et al., 2006 ). These properties are present by the age of 7, and resemble functional brain organisation in young adults ( Supekar et al., 2009 ). The two major hubs of the DMN (PCC and mPFC; also neural correlates of MW), are visible very early on, with DMN formation completed by 2 years of age ( Gao et al., 2009 ). However, formation of the DMN is thought to precede functional specialisation for self-referential cognition and mentalising such as mind wandering ( Gao et al., 2009 ).

An increase in long-range connections, as well as a decrease in short-range connections (segregation) and strengthening of within-network interactions (integration), are thought to govern functional brain development and functional specialisation ( Di Martino et al., 2014 ; Kelly et al., 2008 ; Power et al., 2010 ; Rubia, 2013 ; Rubia et al., 2009 ). The childhood to adolescent years (ages 7–15) are a particularly sensitive period for such functional brain network development ( Mak et al., 2017 ), which is the same age that ADHD symptoms and impairments often emerge ( Asherson et al., 2016 ). We also propose MW is likely to become more frequent during daily life, or even emerge. During this period greater integration develops between DMN and somatosensory regions, contrasting their complete segregation in adulthood. Additionally, early adolescence is marked by a similar degree of DMN deactivation contrasting less task-related deactivations in somatosensory regions compared to adults ( Thomason et al., 2008 ). This deactivation pattern was linked to better task performance in childhood ( Thomason et al., 2008 ), suggesting that the recruitment of somatosensory areas might be a compensatory strategy during high cognitive demand task conditions in children. In summary, while children exhibit a DMN activity similar to adults, the system does still undergo important changes between middle childhood and young adulthood. Therefore, frequency and type of MW may vary with age as function of DMN development.

Within-network integration of DMN hubs ( Fair et al., 2008 ) and segregation from other networks is considered to be a good marker of brain maturation ( Dosenbach et al., 2010 ; Rubia et al., 2009 ), and better than executive control networks whose functional development is less affected by age ( Sato et al., 2014 ). However, executive control networks also show a pattern of strengthening of intra-network and weakening of inter-network connections from childhood to middle adulthood ( Fair et al., 2007 ). These developmental changes are reflected in functional improvement, or greater adaptive control and greater working memory capacity with age ( Fair et al., 2007 ). Similarly, a pattern of increasing anti-correlation between large-scale networks (DMN and FPN) and task-related DMN deactivations is likely to support improved regulation of both executive control and MW ( Fair et al., 2008 ). Potentially, a maturational delay in the functional specialisation of these networks could result in a disrupted regulation of executive control and MW.

4.2. Mind wandering and “Maturational lag hypothesis” of brain development in ADHD

Related to the findings on typical functional brain development, El-Sayed et al. (2003) proposed a maturational lag hypothesis. The hypothesis suggests that a persistent maturational lag in functional brain development might become a sustained functional abnormality leading to symptoms and impairments of ADHD. We further propose that abnormalities in resting-state functional connectivity resulting from co-activation of functionally related brain regions ( Power et al., 2010 ) may lead to the self-generation of excessive, spontaneous and context-independent thoughts, typical of MW, which are externalised as inattentive behaviours over the lifespan. Consistent with this view, recent work in ADHD has shown a maturational lag in major large-scale brain networks, especially within-network integration (DMN and FPN) and interactions between default mode, frontoparietal, ventral attention and salience networks ( Sripada et al., 2014 ). A recent review also summarised findings for decreased synchrony/connectivity between the two major DMN hubs in ADHD ( Castellanos and Aoki, 2016 ). The lagged maturation was associated with DMN interference, poor performance (e.g. greater reaction time variability) during cognitively demanding tasks, and was proportionate to the severity of inattention ( Sripada et al., 2014 ).

With regard to the development of MW in ADHD, to date there has been only one published study, which compared the frequency of MW in children and adults with ADHD ( Van den Driessche et al., 2017 ). Using an experience sampling method, similar frequencies of “mind blanking” (MW without awareness of the content) were seen in 6-12-year-old children and young adults with ADHD. While the authors found no case-control performance differences on the SART, medication-naïve children and adults reported twice as much mind blanking, but fewer episodes of task focus and MW with awareness than controls. We propose that individuals with ADHD in this study tended to report mind blanking rather than MW due to the lack of a coherent reportable content. When comparing a group of children with ADHD treated with methylphenidate with drug naïve children and controls, there was reduced frequency of mind blanking to the level of controls; although the treated group still had a greater frequency of MW with awareness of content than controls ( Van den Driessche et al., 2017 ). Medication was therefore proposed to allow access to awareness of MW. The authors ( Van den Driessche et al., 2017 ) further hypothesised that this effect could be due to restoration of executive resources. These findings suggest similar abnormalities in the frequency of MW-related measures in ADHD during both childhood and young to middle adulthood.

Overall, the developmental studies suggest that understanding the cortical maturation of key networks leading to aware/unaware and spontaneous/deliberate forms of MW, may be important to understanding the onset, course and development of ADHD.

5. Discussion

This review sets out to draw parallels between MW and ADHD, and guide new insights into ADHD psychopathology. The theoretical conceptualisations outlined are designed to set the scene for further hypothesis testing. The basis for this work is the observation that a spontaneous and poorly controlled type of MW is strongly associated with ADHD, and ADHD-related impairments. Currently, there are only a small number of studies that measure MW in ADHD, and none that simultaneously measure ADHD, MW and neural functions associated with both ADHD and MW. The relationship of MW to ADHD symptoms such as inattention is therefore not yet well understood. We therefore set out to summarise what is known about the links between ADHD, MW and their neural correlates.

At the level of neural networks, there are strong parallels in the association of both ADHD and MW with DMN activity during task conditions. Reduced deactivation of DMN activity during tasks requiring sustained attention is associated with the frequency of MW in controls, and is also associated with ADHD compared to controls. Since ADHD is also linked to a specific pattern of spontaneous and poorly controlled MW, a simple hypothesis can be proposed that the normal neural processes that regulate MW are disturbed in ADHD, leading to excessive levels of spontaneous and uncontrolled MW. Furthermore, cognitive and functional impairments that are associated with periods of MW in controls are comparable to the range of impairments associated with ADHD, suggesting that excessive spontaneous MW may underpin functional deficits in ADHD.

In support of our hypothesis we draw on evidence that the usual processes regulating MW are disrupted in ADHD. First, we see that the usual context regulation of DMN and executive control network activity to increasing task demands is associated with MW, and deficient in ADHD. Furthermore, deficient regulation of these processes appears to be reversed by stimulant medications used to treat ADHD. Second, we see that the processes associated with both MW and ADHD are sensitive to the salience of task conditions. In ADHD increasing the salience of task conditions may “normalise” performance and associated neural processes. Finally, we see that both MW and ADHD may be associated with sensory decoupling such as the reduced early P1 response of the occipital cortex to a visual stimulus. We therefore propose that by understanding the processes of normal regulation of MW in the general population, we can identify with more precision aberrant processes in ADHD.

One question that arises from this model is whether measures of MW can be considered distinct from the inattentive symptoms of ADHD. For example, measures of MW may merely reflect alternative measures of the same underlying construct. Currently, there is almost no evaluation of the incremental information provided by measures of MW, although we did report that a rating scale measure of MW was an independent predictor of impairment in ADHD after controlling for ADHD inattention and hyperactivity/impulsivity symptoms ( Mowlem et al., 2016 ). Further research is therefore required to addresses this question. However, since many of the findings related to ADHD also apply to measures of MW, it is a reasonable hypothesis that one reflects the other.

If there is a very close relationship of MW with ADHD-inattention, this would open new avenues for research. MW has the advantage that it can be measured using simple rating scale trait measures, but also experience sampling data in daily life (considered to be more objective reflections of the mental state); and experience sampling during experimental paradigms such as sustained attention tasks, which have been used to investigate the neural correlates of MW in control samples. Measures of MW may also be less dependent than the inattentive symptoms of ADHD on behavioural adaptation, which is influenced by learnt coping strategies, so perhaps a better reflection of the underlying neural condition.

The model we propose views the inattentive symptoms of ADHD as outcomes of MW (i.e. internal distractibility), and MW in ADHD may be a direct outcome of altered neural regulation of internal thought processes. Cognitive performance deficits seen in ADHD may also be a direct outcome of MW. We propose that dysregulated neural functions (DMN overactivity during task conditions for example), are reflected in excessive spontaneous MW, and that such internal distractibility explains behavioural symptoms such as losing track during conversations, avoiding tasks that require sustained attention, not completing tasks, and misplacing things.

Further research is required to investigate heterogeneity the range of internally generated thoughts, and understand the regulatory processes involved. A key question is to fully understand the differences in studies which find that episodes of MW are associated with both reduced or absent ( Kucyi et al., 2016 ; Stawarczyk and D’argembeau, 2015) and present ( Christoff, 2012 ; Spreng et al., 2010 ) co-recruitment of DMN and executive control network regions. In our view, this likely reflects that MW is a multidimensional construct and different types of MW recruit the executive control network differentially.

Spontaneous, unaware (‘zone-off’) MW was associated with decreased functional connectivity ( Golchert et al., 2017 ) and a negative functional correlation ( Gruberger et al., 2011 ) between the DMN and FPN. This pattern contrasts with increased functional connectivity between these two networks during deliberate MW ( Christoff et al., 2016 ). Potentially, both spontaneous and deliberate MW might involve the co-activation of both networks initially. This co-activation allows both deliberate MW and task performance under low demand to be maintained, as well as the controlled and adequate shift to task focus under high demand. Alternatively, this co-activation might also reflect an inability to suppress the DMN activity during on-task conditions. Therefore, constant engagement in spontaneous MW might represent a neural state of overly active DMN hubs during on-task, and hypoconnectivity within the entire DMN at rest. The uncontrolled and spontaneous occurrences of MW will then result in poor context regulation.

In our review, we identified three existing fMRI accounts proposing specific dynamics of MW. The dynamic framework ( Mittner et al., 2016 ) proposes a greater activation of the dorsal attentional network during on-task that transitions to increasing connectivity/activity within the DMN during an off-focused state (selecting between returning to the task or entering a state of MW). Finally, if task-unrelated thoughts appear more salient, an individual enters a state of MW marked by reduced functional connectivity between large-scale networks ( Mittner et al., 2016 ). The other two fMRI accounts speculate on initial recruitment of the right medial temporal lobe, or limbic regions ( Golchert et al., 2017 ) and later FPN ( Fox et al., 2015 ) during MW. However, the dynamics of MW remain poorly understood ( Smallwood et al., 2011 ).

Future research could focus on the use of EEG, which can capture fast and covert cognitive processes such as MW. The increased use of state-of-the-art EEG approaches that provide improved source localisation of EEG signals, combined with EEG’s millisecond temporal resolution, has already demonstrated their better potential to explain the dynamics of MW compared to more traditional scalp-level EEG analyses ( Braboszcz and Delorme, 2011 ; Kirschner et al., 2012 ).

6. Specific predictions from the mind wandering hypothesis for ADHD

The MW hypothesis proposes that altered interaction between the four large scale networks (DMN, executive control network, salience network and visual network), and that deficient DMN deactivation during task activities will lead to excessive spontaneous MW, lacking in coherence and topic stability, which in turn will lead to ADHD symptomatology.

To investigate this hypothesis, future work could apply experimental designs that have been successfully applied to manipulate and measure MW and measures the neural correlates of MW in controls samples, to ADHD case-control studies, or by investigating correlations to dimensional measures of ADHD symptoms. Examples include sustained attention and inhibitory control tasks, varying cognitive load by using manipulations such as altering the stimulus presentation rate ( Christakou et al., 2013 ) or introducing a working memory component ( Baird et al., 2014 ). This would enable investigation of context regulation and sensory decoupling in relation to ADHD. A further manipulation would be to the comparison of high and low reward conditions, to investigate the effects of salience ( Liddle et al., 2011 ).

Inferring causal directions may be difficult because of the close temporal timing of neural, cognitive performance and MW events if they covary strongly with each other. One approach to infer causal relationships is to use treatment interventions such as stimulant mediation, to bring about change in the various outcome measures ( Kendler and Neale, 2010 ). Then the causal relationships between these can be modelled. Mindfulness training is another intervention that is thought to act on the regulatory processes involve in MW and ADHD ( Mrazek et al., 2014 ). Recent studies suggest effects of mindfulness training that are potentially comparable to those seen for ADHD medications ( Hepark et al., 2015 ).

To guide future work, we outline specific predictions derived from this hypothesis.

6.1. Perceptual decoupling

We propose that individuals with ADHD will experience greater perceptual decoupling driven by the proposed ADHD-specific MW, compared to controls during long-lasting (>30 min) sustained attention paradigms. A potential neural correlate is absent or reduced inter-regional synchronisation or positive functional correlation between DMN and visual networks. Using EEG, reduced mean P1 and N1 amplitudes will reflect inefficient early perceptual processes in ADHD.

6.2. Context regulation

We propose that individuals with ADHD will be unable to adapt to increasing cognitive (attentional, control) demands both at the neural level, and behaviourally; and that deficient context regulation of neural activity in ADHD will be related to the frequency of MW. Regarding neural correlates of these processes, we propose that a reduced positive functional connectivity between DMN and salience network will reflect the deficit in switching from rest to task, task to rest and from a low to high demand condition. Another neural correlate will be an absent change in frontal midline theta power from rest to task, hypoactivation in the DMN from task to rest and hypoconnectivity or reduced positive functional connectivity within the DMN (posterior cingulate cortex and medial prefrontal cortex) during rest.

6.3. Behavioural correlates of DMN and FPN dysregulation

We propose that variable reaction times will stem from MW and serve as a behavioural correlate of reduced negative functional correlation (or even disconnection) between default mode and executive control network and hyperactivation within the DMN during cognitive paradigms.

The neural inefficiency in the large-scale networks will manifest in increased phase inconsistency/variability of parietal or frontal theta in response to task-related stimuli, which will coincide with excessively frequent episodes of MW.

Changes in the content and context of MW is likely to reflect differential recruitment of DMN regions (Stawarczyk and D’argembeau, 2015). For instance, depressive thoughts might result in greater connectivity between the core DMN and salience network, and a weaker connectivity between these two networks with the FPN and the medial temporal lobe (DMN hub). Excessive MW was correlated with the highest degree of DMN activation, suggesting that overactivity of the DMN might reflect the frequency rate of MW ( Kucyi et al., 2016 ). Therefore, MW in ADHD will be characterised by hyper-connectivity within both right medial temporal lobe and right medial prefrontal cortex (DMN hubs) during on-task.

7. Conclusion

Converging evidence indicates that both MW ( Kucyi et al., 2016 ) and ADHD ( Sidlauskaite et al., 2016 ) are linked to DMN regulation and regulation of the interaction between DMN and FPN. In particular, ADHD is associated with both within DMN and between DMN-FPN dysregulation. These neural effects are present in ADHD independent of age, clinical characteristics and type of task ( Cortese et al., 2012 ; Plichta and Scheres, 2014 ), supporting the MW hypothesis. A dysfunctional and later absent interaction between the four major networks (DMN, executive control network, salience network and visual network) is proposed to underlie different aspects of cognitive and behavioural impairment associated with MW in ADHD.

Future studies should focus on understanding whether completely different neural processes underlie MW in ADHD compared to controls, or there is simply neural attenuation in ADHD. Understanding context regulation requires the use of conditions varying in cognitive demand. Another necessary study is to measure effects of reward, or whether reward ‘normalsies' MW in ADHD compared to controls. Importantly, validation across different MW measures and conceptualization of different types of MW will enable the investigation of neural activity underlying specific types of MW.

Conflicts of interest

Professor Jonna Kuntsi has given talks at educational events sponsored by Medice: all funds are received by King’s College London and used for studies of ADHD. Kings College London research support account for Professor Philip Asherson received honoraria for consultancy to Shire, Flynn-Pharma, Eli-Lilly, Novartis, Lundbeck and Medice; educational/research awards from Shire, Lilly, Novartis, Flynn Pharma, Vifor Pharma, GW Pharma and QbTech; speaker at sponsored events for Shire, Lilly, Novartis, Medice and Flynn Pharma.

Acknowledgements

Philip Asherson’s research is supported by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London, and an NIHR Senior Investigator award (NF-SI-0616-10040).

Natali Bozhilova’s research is supported by a studentship awarded by the Medical Research Council, as part of a doctoral training programme (DTP).

Dr Kai Syng Tan is the author of the figure to this paper. We would like to thank her for visualising the MW hypothesis through her brilliant artwork. http://kaisyngtan.com/ .

Professor Jonna Kuntsi has given talks at educational events sponsored by Medice; all funds are received by King’s College London and used for studies of ADHD.

This paper represents independent research part funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

We would like to thank Jonny Smallwood, Katya Rubia, Florence Mowlem, Bartosz Helfer, Celine Ryckaert and Talar Moukhtarian whose research and hard work has inspired our theoretical views.