That Neuroscience Guy - The Neuroscience of Brain Overload Part Two -Cognitive Overload

Episode Date: February 26, 2024

Do you ever feel like so much is going on that you just can't handle anymore? In this week's episode of That Neuroscience Guy, we finish our discussion on brain overload by discussing cognitive overload. Quick LinksGet Embed PlayerShare on SocialDownload Audio File  

Hi, my name is Olof Kerg Olsson, and I'm a neuroscientist at the University of Victoria. In my spare time, I'm that neuroscience guy. Welcome to the podcast. On the last episode of the podcast, I talked about sensory overload. That's when too much sensory information is coming into the brain and your brain basically can't process it all. Your attentional filter fails and as a result, there's some interesting consequences. Basically, you either miss sensory information or you might engage the fight or flight or freeze response. But there are other kinds of overload that your brain experiences. Have you ever felt like your thinking itself is impacted? You cannot seem to work through a

problem or process information. It's like your brain itself is like wandering through quicksand and it just seems really sluggish. Well, there's a lot of reasons for that, and we've talked about some of them. But another reason your brain can react that way is from another kind of overload, and that's cognitive overload. So you've guessed it. On today's podcast, cognitive overload. I'm going to start with a simple example, and it's one that I've used before when I was talking about attention, but we're going to talk about a simple example, and it's one that I've used before when I was talking about attention, but we're going to talk about it in terms of cognitive overload. And it stems to the reason why you shouldn't use your cell phone while driving.

So, in terms of attention, if you remember the story, if you are driving and talking on your cell phone, you're going to be focused on your cell phone and not focused on the road. So you're going to miss information and that might lead to an accident. But you can explain this in terms of cognitive overload. Basically, there's a cognitive demand to talking. You have to use cognitive effort or what I'm going to call cognitive capacity, which I'll explain in a second, to talk. Because you're thinking about what you want to say, right? You're engaging the prefrontal cortex and you're thinking about the words you want to share with whoever you're talking to.

But there's also a cognitive demand to driving. You know, driving is not something that's automated. We have to process information and act on it. And that does, again, engage the prefrontal cortex. We have to think while we drive. Even those instances where we don't remember the drive home, we're still thinking while we're doing it. We're just choosing not to remember it. Now, before I get into where the problem is, I mentioned this idea of cognitive capacity. Basically, the way you can think about cognitive capacity is that your brain can only do so much at one time.

It's almost like a form of energy, which it isn't. It's a concept. It's an idea. But let's use energy as an example, and I'll try to explain the neuroscience behind it. But your brain has a finite amount of energy. That's actually true in terms of energy sources in the brain, but not quite where I'm going with this. But when you choose to do a cognitive task, it takes some of this energy. And if you choose to do another task at the same time, or the task is simply too demanding for you, it's going to exceed the amount of cognitive energy that you have, or the cognitive capacity. And when you exceed your cognitive capacity, performance is reduced. That's basically the outcome of what happens in that situation. So let's get back to driving. You have a finite

amount of cognitive capacity and you're using a fair bit of it because you're engaged in a conversation. However, you're also using your cognitive capacity to drive, right? You're using that cognitive energy. And when you're using a cell phone while driving, basically you exceed your capacity. And because you're focused on the conversation, then what happens is your performance is reduced in terms of driving, which is what leads to more accidents. And the reverse can actually be true. If you're trying to talk on your cell phone while driving, and please don't do this, that's why we have laws against it. If you're really focused on driving and you're using your cognitive energy while driving, well, then your performance is reduced on talking and you might say some things that are a bit random or miss

parts of the conversation. And again, it's because you exceeded your cognitive capacity. Now, there's also a lot of things you shouldn't do while driving. You probably shouldn't be eating while you drive, or playing with the radio, or possibly even talking to the person in the car, because again, you're pushing your cognitive capacity. Now, here's another example to try to get at this. Say you're in a classroom and you're listening to a teacher, but you're also planning what you want to do that night.

Now, there is an attentional issue here. It's the same sort of argument. If you're putting attention into paying attention to the teacher, you're probably not thinking much about what you're going to do that night. And if you're thinking a lot about what you're going to do tonight, you're probably not listening to the teacher. So you can use an attentional explanation for this, you can use an attentional explanation for this. But you can also explain this in terms of cognitive capacity. So thinking about what you want to do tonight, take some of that cognitive energy or cognitive capacity, and you basically can't pay attention to the teacher, or you can't use cognitive capacity to process what the teacher is saying. And that's the key difference. You could even be paying attention, but you don't have enough cognitive capacity to process what the

teacher is saying. Therefore, you miss some of the information. So the attentional system and the cognitive system here are interacting together, but you can use both explanations, and they are different. Now, what is cognitive capacity? Well, the simple version is you only have so many neurons in the brain. I know we said we have about 86 billion, but they get tied up doing a bunch of things. And if a bunch of neurons are activated on task one, and you need those same neurons for task two, well, they're simply not there, right? They're busy firing, doing another pattern of activity.

Therefore, performance is reduced. And if you remember, we've talked a bit about how the brain works on a number of occasions, but you don't need every single neuron for something to happen. You just need, you know, most of them. It's a statistical sort of thing. And as long as you have most of them, you'll be okay. Even if you're not using some of the neurons you need, you can probably still do the task. It's just performance

will be reduced. Now for a while, admittedly it's been about a decade, my own research team examined this very issue and we ran two studies looking at cognitive overload. So the first study we did was in terms of learning. And we did a very simple study. It's going to sound a bit ridiculous, but we had people learn a task, and they had to use a trial and error strategy to learn the task, right? So if they guessed right, they were told they're right. If they guessed wrong, they were told they're wrong, and eventually they would figure out what they needed to learn, and those right explanations would guide them to the solution, if you will. Now, we did two feedback conditions. This is the manipulation.

So in one condition, we simply said, you're right or you're wrong. All right. And it's a very simple form of feedback that your brain processes very quickly. In another experimental condition, we gave people two numbers. And if the numbers were added up to an odd number, then you knew you were right. And if they added up to an even number, then you knew you were wrong. Now, what we've introduced here is cognitive overload in a sense, or at least we've increased cognitive load. It takes far more cognitive effort or capacity to process the feedback condition when you add up the numbers and they're even or they're odd than it does for the simple right or wrong.

And what we observed was fascinating. We found that the learning signals in the brain were reduced as cognitive load increased. So as you increase cognitive load, you're learning signals that are sensitive to feedback and basically the mechanism that changes the wiring in your brain, those signals are reduced. So cognitive load had this negative impact on learning. In the second time we did this, we induced cognitive load in a different way. Basically, in one condition, we had people learn something again. It was just a very simple task. And in the second condition, the second experimental condition, we basically had people learn something, but while we were increasing their cognitive load. It's called dual task,

which is the examples I used before. So we gave people a secondary task to do while they were trying to learn the first task. And again, what we found was interesting. We found that the brain signals were reduced when we increased cognitive load with a dual task situation. So the bottom line is your learning system in your brain or learning systems, there's more than one, are negatively impacted by increasing cognitive load. So if you want to learn more effectively, one tip you can pull from this research is that you want to reduce cognitive load as much as possible. You want to keep things simple. Now the second result with the dual task

performance has been replicated by other research groups in terms of decision making. Basically, they had people make a series of decisions. All right. We're talking very simple sort of decisions like, you know, what do you want to have for lunch today? What time are you going to go to bed tonight? And what they found is by increasing cognitive load, if you look inside the brain, they could see an increase in activity in the prefrontal cortex. So what should be a simple problem to solve became a more challenging problem to solve. And as a result, performance was

reduced. Now, in most cases with these simple decisions, people still get to the right decision. It just takes them longer to do it. But if the task is more challenging, so imagine, and this has been done in medical diagnosis, if you increase cognitive load when a doctor's making a medical diagnosis, you reduce performance and you can actually impact accuracy. You can make doctors make the wrong clinical decision. And if you think about the way an ER works, this is fascinating because cognitive load, like, are you kidding me? They're making multiple decisions within minutes or seconds of each other. There's a lot going on. So they probably have a sensory overload issue, but they also have a cognitive overload issue because they're

thinking about too much at the same time and their cognitive capacity is exceeded. too much at the same time, and their cognitive capacity is exceeded. So what sorts of factors can influence cognitive load? Well, the short answer is basically anything that impacts the brain. So stress, for instance, we know that stress impacts the brain in a negative way. We've talked about that on a previous episode, but it basically also reduces your cognitive capacity. You're more likely to reach cognitive overload when you're stressed. The same is true of anxiety. All right, if you're anxious, it reduces your cognitive capacity, so you're more likely to reach a state of cognitive overload. And you know what's coming, sleep, diet, and exercise. All of these things, if we eat a poor diet, we don't

sleep enough, we don't exercise enough, they result in a decrease in cognitive capacity. Therefore, you're more likely to have an increase of cognitive overload and therefore your performance and whatever you're doing will be reduced. So what do you do about cognitive overload? Well, it's the reverse of what I just said, right? Reduce stress, reduce anxiety, make sure you have a healthy diet, make sure you get enough sleep, and make sure you exercise as much as you can, preferably daily. All right, there you go.

Cognitive overload. What it is, how it works, and hopefully what you can do to help it. Don't forget to check out the website, thatneuroscienceguy.com. There's links to Etsy where we have our merch up and there's links to Patreon. Remember a dollar a week, a dollar a month, whatever it is, Patreon allows you to send money to support the podcast and students in the Craig Olson Lab. Basically Matt, who we're going to have on soon. And he's going to tell you all about his research and what's interesting about it. So you'll, you'll know who you're sending money to. Of course, we want to know what you want to know about the neuroscience of daily life. So reach out on X or threads at that neuroscience guy, or email us that neuroscience

guy at gmail.com. And finally the podcast, please subscribe if you haven't already and thank you so much for listening my name is oliv krigolson and i'm that neuroscience guy i'll see you soon for another neuroscience bite