The Human Brain: Episode #5
When you form a goal in your mind, and then manage to avoid distractions and carry out that goal, what's going on in your brain? Todd Braver, professor of psychology and neuroscience at Washington University in St. Louis, shares some of his past and upcoming research into cognitive control.
Claire Navarro: In 2005, Todd Braver and his family set off for England. Dr. Braver is a professor of psychology, neuroscience, and radiology here at Washington University in St. Louis. He had been invited to spend a year as a visiting fellow at Cambridge. Like many newcomers to England, Braver quickly realized that not everything is exactly the same as in the United States, especially once you get in a car.
Todd Braver: As you probably know and the listeners know, in England, everything is on the reverse in terms of driving rules. You drive on the left side of the right, but the steering wheel is on the right. And the instrument panel is on the right. And the rules on the road are opposite. So the very first time I bought this car and set out to drive, all of the sudden I realized all of the driving rules and all of the knowledge that I had was an interference. I felt myself very consciously thinking to myself, “Ok, if I want to turn on my turn signal, it’s not on the left side where it would normally be; it’s on the right. If I’m looking to make a right turn, I have to look in the opposite direction than I think.” So I was really keeping all these rules in my mind, really attending to them very carefully, and when would I set out to drive, I would go through a kind of mental checklist: “OK, what am I going to be doing on the very first couple trips.”
CN: To drive safely, Braver had to use cognitive control. It’s what we all use when we set a goal, whether at work or at home or, in this case, on the road, and then carry out that goal. Braver does research on cognitive control, so he more than just about anyone can tell us exactly what was going on in his brain as he drove around the streets of Cambridge. According to Braver, there are two main types of cognitive control: proactive and reactive. When you really concentrate and are always reminding yourself of your goal, that’s proactive control. That’s what Braver was using when he first got to England.
TB: So that was a really proactive mode I was engaged in, because I really knew that I cared about my family, didn’t want to get in an accident, knew it was going to be challenging, had this expectation, and knew what my goal was.
CN: As he got more familiar with the lay of the land, Braver didn’t have to constantly think about every rule of driving. If he momentarily forgot about some rule, a quick reminder from a sign would be enough to grab his attention. But even though he wasn’t concentrating quite as intensely, he was still using cognitive control; he had just shifted to another mode, one called reactive control. There are a couple main differences between reactive and proactive, which he was using earlier.
TB: The difference between these two modes is really in terms of the time course. Where as the proactive mode is a more sustained and anticipatory mode where you are keeping that information over some period of time in your mind so that you can help anticipate these events. The reactive mode we think of more of a “just in time,” a more transient mode of control that arises when the need arises and only really when the need arises.
CN: Through brain imaging, Braver has looked into what’s really going on in our heads when we use both of these modes of control. For example, both involve the prefrontal cortex—the front part of your brain behind your temples. But even though the two modes use the same part in the brain, there are real differences between the two modes.
TB: What we found is that under different situations, the prefrontal cortex seemed to have different kinds of time patterns of activity, time course of activity. In situations in which we had hypothesized as we started thinking about this that it might be more proactive mode, we would see the activity starting earlier, that we would get some cues from the environment that the demands might be higher, and persisting for longer periods for time.
CN: With reactive mode, the activity started later and didn’t last as long, and there was another major difference. In addition to the prefrontal cortex, when people used reactive control, a bunch of other networks in the brain would also light up.
TB: Under these more reactive control situations, we would see another brain region that tends to coactivate with this prefrontal cortex called the anterior singular cortex, and it seems to be the brain’s detector of danger or interference. That would come on, and then we would see the prefrontal cortex but also a lot of other regions in the wider control network. So if you need to react more quickly, you might need a more broader set of brain regions to engage more quickly and also might need to be driven by a detector: “Oh yeah. This is an event that causes me to retrieve or reactivate those goals.”
CN: It’s amazing just to be able to take a peek into the human brain and see what’s going on when people set goals and carry them out. But this kind of work raises so many more questions. Lets say two people come into Dr. Braver’s lab and are asked to do some word games. A lot of what happens in participants’ brains has a lot to do with the type of problem or task they’re given. But even when doing the exact same problem, people’s brains will react differently. Some people seem to prefer using proactive control; others lean more toward reactive control. Some brains seem to react more or less quickly. Why? To answer that question, you have to start thinking about motivation. Why do people ever try to solve problems? This question fascinates Braver.
TB: One of the things that got me really interested in this question was a fairly mundane observation but one that comes up for all of us that do experimental research, which is, you know, we ask people to do hard cognitive tasks in our laboratory all the time, and we are at an institution where most of the people who come to our experiments are pretty high functioning (they like to do tasks, they’re good at it). But some of them we find, they think, “This is great!” And they really try their hardest, and they don’t feel bored at all by it; they’re disappointed if they make any errors. Other people come in and they don’t care very much—we would say they’re unmotivated. It begs the question to me that when we say, “OK, they’re not motivated. They’re not performing their best,”—that really says what is their connection between motivation and our cognitive systems? Why do we not always perform at our best? One of the things that I think we have come to a perspective on is this view that our engagement of our cognitive systems, we kind of think of it as a cost-benefit trade off, which is—we don’t know why yet, and we are interested in this, but some things are cognitively effortful. If I gave you a list of hard math problems to solve right now, you might do it, but your brain might be tired, and you might not like doing it even if you can preform well on it. So for whatever reason, which we are not sure about, our brains find engaging cognitive control after a sustained period of a time somewhat costly. We might try to not exert it very much unless the situation warrants it. What we think is that our brains are making these implicit decisions all the time: you know, “in this situation, here is how much it is cognitively going to cost me, and here is what I’m going to get if I do that. Is it worth that?” We think that our brains are making these motivational decisions even when they are not being stated explicitly. But if we are interested in studying that, what we need to do is now put that under experimental control, explicitly make it more valuable or less valuable to do well in the task and then study how manipulating the motivational value of your cognitive task and your performance, how that changes what’s going on in your brain.
CN: Some of these kinds of experiments are already underway. As it turns out, one way to motivate people is to give them money.
TB: We’ll do some situations where we’ll say, “You are doing a difficult task, and if you do well—if you are fast and you are accurate on this test—each trial that you do well, you’ll get a little monetary bonus.” When we do that, we find that they people who are most sensitive to the rewards, in terms of self-reported personality traits, they seem to shift their brain activity, and their performance seems to be in this more proactive mode.
CN: But even money on the table doesn’t have the same effect on everyone. Some people get more excited about being rewarded for their work or about the possibility of getting a little extra cash. For other people, this isn’t as important. There are a lot of possible explanations for why people use proactive or reactive control in different situations. Some people’s brains might just be better or more efficient at one mode or another, so they tend to stick to that mode. By looking into these kinds of differences and thinking about how things like motivation and personality effect how we use our brains and how we accomplish our goals, Braver is reflecting a new way of doing neuroscience.
TB: In earlier history of psychology and neuroscience, there was a big separation between the people who studied motivation and learning and emotion and the people that were studying cognition. So the people that were studying cognition—attention and learning and short-term memory and long-term memory—thought about this as being very cold and as being the rational part of our brain and that it really wasn’t impacted by these motivational things. Or at least, that was a different area of study, and they didn’t really have to worry about that. I think as we know more about the way brains are organized, we know the brain doesn’t really separate out into a motivational part; they are all interacting together. I think there is now more of an appreciation that the reason we engage in cognitively demanding activities, it is because of motivational reasons that we value the outcomes when motivated to do that. There is a new appreciation that we need to put these things together in our study of it.
CN: Next up, Dr. Braver is looking at how sets of twins use cognitive control. This project is just starting up, and it could reveal exciting new information about how genetics, upbringing, and personality effect how people carry out their goals. Some time in the future, this information could help scientists figure out ways to help people be more productive or more successful. So, stay tuned. Many thanks to Todd Braver for joining Hold That Thought. For many more ideas to explore, including more from our series on the human brain, be sure to visit our website: holdthatthought.wustl.edu. And subscribe to our weekly podcast. You can also always find us on Facebook, Twitter, SoundCloud, PRX, iTunes, and Stitcher. Thanks so much for listening.