That Neuroscience Guy - The Neuroscience of Mind Wandering

Episode Date: July 10, 2023

Whether it is in the classroom, in the office, or even at the dinner table, it's common for our minds to wander from the current setting. But why do we let our minds get away from the task at hand? In today's episode of That Neuroscience Guy, we discuss the neuroscience behind mind wandering. 

Hi, my name is Olaf Kergolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. So like a lot of the things I talk about, this has happened to all of us. You know, we're sitting in a classroom,, we're sitting in a classroom or we're sitting in a meeting or we're even just having conversation with friends over the dinner table. And all of a sudden, we're just not there. We're mind wandering. That state where your brain is just not paying attention to what it probably should be paying attention to, and it's kind of hopping from subject to subject or possibly even just sitting there in idle.

It's actually a bad thing and a good thing. So let's talk about the neuroscience of mind-wandering. Okay, I think most people get the idea of what mind-wandering. Okay, I think most people get the idea what mind-wandering is. We all experience it. And I was trying to find some statistics on the percentage of time that we spend mind-wandering. And the estimates range from 20% of your day to 80% of your day. And I think it's very dependent on a lot of factors. So it's hard to tell for sure, but we all do it. We all mind wander. Now, what causes it?

Well, basically, it's a failure of attention. And we've talked about attention a lot on the podcast. So I don't want to get into it too deeply. But just as a reminder, you know, you have an attentional system. it too deeply. But just as a reminder, you know, you have an attentional system. And basically, the whole point of your attentional system is, let's say you're listening to me right now, is it's basically going to increase the gain of the signal for my voice. In other words, your brain is really going to focus on processing my voice. And we're going to tune out stuff in the background. And when you mind wander, you have a failure of attention, which basically

means your attentional system sort of forgets to listen to my voice, if we stick with that example. And it either focuses on something else. So for instance, you might take a look at the television screen and see what's on, or you might literally be just paying attention to nothing. There's a lot of theories about which way you go and why. The classic explanation, if you're looking at your television screen as opposed to listening to me right now, it's because something there captures your attention. That's theory number one. So you see something that interests you and your attentional spotlight, if you will, adjust to the TV screen and goes away from my voice. The other theory that's out there is you're not particularly interested in this topic. And

because you're not interested, the attentional system is more likely just to latch onto any other thing that may or may not be interesting. Now, your attentional system all comes from your posterior parietal cortex, back of the head, it's behind the midline, behind the somatosensory cortex. And we did a couple of episodes now on attention, so I don't want to go into it in too much depth. But the reason if you're mind-wandering right now, and if you're not, snap back, all right? But if you are mind-wandering right now, the reason you might be missing some of the words in the conversation, or at least what I'm telling you, is what we call gating theory. Another way to think of attention is it's because the spotlight is somewhere else, less information is getting through.

So you know I'm speaking and you might pick up the occasional word, but you're also missing things. And it's because your brain can only handle so much incoming information. And another thing that your attentional system is doing is it's sort of prioritizing things. So if you are looking at the TV set, that's priority number one. So it wants to get as much information through as possible from that. And it's trying to keep up with other things, but it just can't do the job. And of course, this is why talking on cell phones when you're driving is a bad thing, is because in principle, if you're talking on your cell phone, your attention is focused there

and not through the windshield of the car and on things that you might want to pay attention to. So what causes mind wandering? It's basically a failure of attention. And like I said, two reasons. One, something captures your attention. Or two, you just don't find the content interesting. So your mind begins to wander. interesting. So your mind begins to wander. Now, mind wandering isn't all bad. And again, we've talked about this before, but I want to go through it briefly. It's the default mode network. And we've got, I don't think we have a full episode on it. I'd have to look through all the episodes we've done at this point, but we've mentioned it a lot. And basically the default mode network is a brain network that includes the medial prefrontal cortex, the anterior cingulate cortex, the posterior cingulate cortex, the precuneus, and the inferior parietal cortex. Now, to be fair,

it's still being mapped out. For instance, fairly recently, the medial temporal lobe is being looped into this network. And if you remember what I've talked about in the past, the medial temporal lobe is being looped into this network. And if you remember what I've talked about in the past, the way the default mode network works is essentially it becomes active when your brain isn't doing things. If you remember the story I told before, it was kind of discovered by accident. Someone decided to look at the fMRI activity in people's brains when they weren't doing the experimental tasks. So just when they were on a rest break or in a state where they just weren't required to do anything, and they saw this increase in activity in the default mode network. Now, the reason why I say it's important is while it's still being investigated, the default mode network is thought to play a very prominent role in memory formation.

So when we talked about memory on previous episodes, we've talked about the idea of consolidation. So when your memories firm up and we I know when we talked about sleep, for instance, I implicated the idea that a lot of consolidation occurs when we sleep, but not all of it. the idea that a lot of consolidation occurs when we sleep, but not all of it. It also occurs during the day. And one of the working theories is that during the day when consolidation is occurring is when the default mode network is engaged, i.e. you're not paying attention to something else. More recently, people have talked about the default mode network as being possibly a locus for imagination. So the generation of new ideas. When your brain is in this state of mind wandering and this default mode network gets engaged,

you are more likely to be creative and think of new things. And that's because you're not focused on the task at hand. At least that's the working theory. So that brain network would be implicated heavily in this idea of imagination and creativity. And the other thing that happens with the default mode network is you can't stay switched on the whole time. All right. You cannot have your brain engaged the whole time. So the idea is, is that the default mode network is a form of relaxation in a sense. It's just what your brain is doing when you're not focused on a task and executing a task. Now, one of the reasons I want

to talk about mind wandering is it's research that I've done with collaborators within my own lab. Basically, what we did is we wanted to study what's going on in the brain when people mind wander. And studying mind wandering is actually really hard to do. The reason is simple, is that how do you know when someone's mind wandering? So what we did is we gave people two tasks. One that was an attentional task, where they had to pay attention to what was happening on a computer screen. And when I say task, I basically mean game. And they respond one way for one stimulus. They respond another way for another stimulus. And we can use that to measure their brainwave activity. And by doing that, we can study

whether they're paying attention or not or how much they're paying attention. And I did an episode way back in season one where I talked about what EEG and brainwaves are. But if you just think of it as our ability to measure a neural response, and in this case, one specific to attention, that's the best way to think of it. And what we did is we had to probe people. So every once in a while, it would pop up and basically say, were you mind-wandering or not on the last 20 seconds or so?

And the idea is that people would self-report that they were mind-wandering. So what we found is that when we looked at their brain response when they were mind-wandering, admittedly by self-report, as opposed to when they were reported being on task, we found that those neural responses were reduced. And that makes sense because if your brain isn't focused on the screen, then that attentional response would be reduced. Then we also did a task where we looked at error monitoring. So we basically had people, it's a learning game where people learned something new. They're basically learning a

relationship between a pair of doors on the screen. And whether they, if you pick the door, do you win money or not? You can kind of think of a game show and you have to figure out which door is better because the one that wins doesn't pay out all the time. And the one that loses doesn't lose all the time. So you're playing this game and you're trying to figure this out and we can measure a brain response there which is basically your brain response uh to whether you're right or wrong um we happen to call it a reward positivity uh now and what we found using the exact same idea we probe them are you mind wandering or not And when people are mind-wandering, those reward signals, their

evaluation of right or wrong is reduced. So again, it makes sense. When you're mind-wandering, your brain is not on task and your ability to effectively evaluate errors or to learn is impacted greatly. So there's a bit on the neuroscience of mind wandering. What causes it? A failure of attention. It's not all bad because the default mode network gets engaged. And as I highlighted with some of my own research, basically we have empirical proof that your brain performance is reduced when you're mind wandering or not as effective. Anyway, that's all I have on mind-wandering.

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