Chapter Content
Okay, so, let's dive into how our brains actually make decisions. You know, it's kind of wild when you think about it.
There's this woman, Jenny Radcliffe, and she's known as "The People Hacker" online. I mean, she calls herself a "burglar for hire" and a "professional con artist," but officially she's a penetration tester. Basically, companies pay her to break into their buildings and computer systems to, like, find weaknesses in their security. And get this – she does it mostly using psychology. She can read people, read situations, and predict how they'll react to, like, whatever she throws at them.
So, there was this one time she was hired to break into a bank in Germany. The whole mission was to get inside during business hours, get past security, and find this specific office where she had to plug a USB drive into a computer. The drive would install some software, you know, letting the company know she'd successfully, uh, breached their security.
The day of the job, Jenny gets all ready. She even puts a bandage on her hand and wrist, thinking people might, you know, hold doors open for her if she looked injured. Smart, right? She also brought this big box of papers, like, overflowing with files, to make it even more likely that people would help her out.
So, she walks into this grand bank lobby with these fancy leather sofas, and heads towards the doors leading to the “employees only” area. But, the doors had fingerprint scanners. Of course, her fingerprint wasn't in the system. She wasn't an employee. But she puts her finger on the scanner anyway, just to check. Beep, no luck, as expected.
Now, she could ask the security guard to let her in, but, like, why would he? That's his job, to keep people out. So, instead, she does something kinda crazy... she just starts swearing, really loudly.
The security guard, as she planned, comes over to see what's going on. Jenny's strategy is, like, brilliant. She always says, “You don’t have to work on the lock, work on the person behind the security.” So true.
When the guard gets there, she says, super impatiently, "This isn't working. It was working yesterday!" The guard suggests she try the fingerprint sensor again. She makes a big show of being annoyed, cursing some more, awkwardly balancing her box of papers on her bandaged hand. She tries again, beep, nothing. The guard suggests maybe she isn't pressing hard enough. So, she grudgingly puts her finger on the sensor again. And, get this, the guard takes her hand and tries to help her press her finger onto the machine!
Jenny yelps like she's in pain, swears loudly again. She then drops the whole box of papers, scattering them everywhere, and starts picking them up while, you know, continuing to swear. Now she's got everyone's attention.
Finally, the guard says, "For God's sake, just go in," and he buzzes her through the doors. Jenny says a quick "Thank you," and she's in! She finds the office, plugs in the USB key, mission accomplished.
So, why did this work? Jenny knew that in Germany, people generally feel really embarrassed by a scene, and because of how she looks, she knew she wouldn't be seen as a threat. She figured the guard would see her as low-risk and would rather just buzz her in than deal with the discomfort of a spectacle. And she was right.
Now, you might be tempted to judge the guard, but honestly, most of us would probably do the same thing. We want to see ourselves as helpful and kind, and we usually don't think people are trying to deceive us. If Jenny had actually been an injured employee, the guard's actions would have been helpful, not harmful.
Jenny's understanding of how we make these decisions, you know, the almost unconscious calculations we do when choosing between options, that's what let her break into the bank. And, advances in neuroscience are actually helping us understand what goes on in the brain during these moments, and this includes what scientists call the "value system."
Basically, our brain’s value system computes the value of different possible choices, picks the one with the highest value, and then tracks how rewarding that choice turns out to be. It all happens super fast. And, like Jenny knew, it depends on what our brains are paying attention to at the moment. So many factors can shape it: our goals, how we feel, our identities, what we think others will think, cultural norms, and, you know, a whole lot more.
After she broke into the bank, the bank could, in turn, might take steps to ensure a different outcome to guards’ value calculations in similar situations in the future. Making the guards aware of how Jenny broke in could empower them to exert more agency over their decision-making in such a moment and resist future attempts to hijack it in that way. Or, the bank might provide more opportunities for security guards to get to know the other bank employees so that it would be clear when a new employee joined, as well as who was a stranger.
One of the cool things about the value system is that it takes complicated, messy decisions and boils them down into, like, comparable quantities. Makes it easier to choose. You know, it's like a hidden game of "Would You Rather?"
It's pretty amazing that we can even answer "Would You Rather?" questions, comparing completely different things. But our value systems are what help us make those choices. But, how does our brain actually do it?
For a long time, no one knew. Did the brain have different systems for each aspect of a choice? Or did it have different systems that handle choices in different areas, like food versus social situations?
Back in the 1950s, researchers started mapping brain regions that tracked simpler rewards and guided animals to maximize those rewards, even if it was bad for them in the long run.
These scientists, James Olds and Peter Milner, found that rats would repeatedly press a lever that stimulated parts of their brains that made them feel good. They even gave up food to press that lever.
Later, scientists found similar reward systems in monkeys and eventually in all mammals, including us. When they stimulated neurons in the striatum and the front of the brain, the animals seemed to experience reward and sought out the stimulus again and again.
But it took decades to figure out how this related to more complicated human decisions. Why would a system that tracks food or lever-pressing have anything to do with, like, who you want to be president or what movie you want to see?
In the mid-2000s, there were some big breakthroughs, including some experiments involving Kool-Aid and monkeys. Camillo Padoa-Schioppa and John Assad were studying decision-making, and they wondered if the reward system could help monkeys make more complex decisions.
So, they gave monkeys choices. Would they like one drop of lemon Kool-Aid or two drops of peppermint tea? Five drops of milk or one drop of grape juice? The monkeys would look left or right to indicate their choice.
After lots of trials, the researchers could figure out how much value each monkey assigned to each drink, what neuroscientists call "subjective value." It wasn't about the objective properties of the drink, like sugar content. It was about what the monkey *wanted* at that moment.
And, what's interesting is that subjective value was influenced by context. The monkeys' preferences changed from day to day. You know, like how you might prefer coffee to tea, but if it's late at night, you'd probably choose tea so you can sleep. Similarly, on Tuesday Gizmo might prefer grape juice to water 3:1, but on Friday he might feel less strongly because he’s already had plenty of fruit and may prefer the grape juice to the water only 2:1.
When the researchers looked at the monkeys' brains, they found that neurons in the orbitofrontal cortex fired in response to the monkeys' subjective preferences for the juices. It didn't depend on the specific ingredients or where the drink was on the screen. It tracked the overall, subjective value.
And, they could even predict what the monkeys would choose just by looking at what was happening in their orbitofrontal cortex. The monkeys' brains were using a common scale to compare, like, apple juice and orange juice.
It turns out that, around the same time, scientists found similar responses in the human brain. People’s brains kept track of the subjective value of different foods, and chose accordingly.
In one study, Hilke Plassmann and her colleagues found that when people were willing to pay more for snacks, they showed similar activity in brain regions as the monkeys who were choosing between lemonade and grape juice.
But what about choosing between things that are *really* different, like grape juice and a movie?
Well, researchers gave people a budget and let them bid on snacks, DVDs, and even monetary gambles. They found that the ventromedial prefrontal cortex tracked how much people were willing to pay for all of those different things.
This suggests that a common system was keeping track of the value of a wide range of choices.
So, this group of brain regions, including the ventral striatum and ventromedial prefrontal cortex, became known as the "value system." By 2010, they had shown that it tracked financial choices too, like whether you'd rather have $10 for sure or a 50% chance of winning $20.
By 2011, researchers could even predict what people would choose *later* based on activity in their value systems. Even if they weren't actively making a decision at the time. The value system seems to be always running, registering the value of things, even when we aren't paying attention.
So, nowadays, it's pretty widely accepted that our brains can make calculations using a common value scale, allowing us to compare things that aren't inherently comparable. You can decide if you'd rather snuggle a puppy or have $5.
When Jenny yelled for the security guard, he quickly made a decision to try to help her, then eventually to let her through.
Now, it's tempting to think there are good choices and bad choices, but the truth is that it all depends on the situation, and the value system is always weighing different interests and the context.
This means that the choices we make depend on what options we *think* we are choosing between and what aspects of the choice we focus on. And, the value we assign to something can change based on our past experiences, our current situation, and our future goals.
So, if you're deciding between salad and cake, you might focus on taste, how you'll feel after eating it, what your date is eating, whether you just got a bad doctor's report, and so on. Your brain does this super quickly. Then it chooses the higher-value alternative.
Once you've made the choice, your value system keeps track of how good the outcome was, relative to what you *expected*. It tracks the difference between your prediction and the actual result. If the choice is better than you expected, that's a "positive prediction error." If it's worse, that's a "negative prediction error." These prediction errors help you learn for the future.
So, there are three basic stages to value-based decision-making. First, our brains decide what options we're choosing between and assign a value to each one. Next, we go with the highest-value choice. And finally, our brains track how rewarding it turns out to be, so we can update our calculations for next time.
If the guard buzzed in Jenny and it was better than he expected, he'll be more likely to let in the next bumbling stranger. But if something bad happened, he might think twice next time.
Most of these studies have been done in labs. But can we link activity in the value system to what people do in their real lives?
Back when I was a budding neuroscientist, I was interested in whether brain imaging could help us understand health decision-making. I wanted to help people make choices that would lead to healthier, happier lives. I also knew that these choices could be very difficult to make. It's hard to change, and even when we are motivated to change, we don’t always take time to figure out why we do what we do in the first place or know why some ways of thinking are helpful in achieving our goals, and some aren’t.
I wondered if brain imaging could give us a new window into this decision-making. Maybe looking at brain responses to health campaigns and health coaching messages could help us understand what made people change and what would make it easier to work with, rather than against, our desires. If that were true, maybe it could help us design and select better messaging.
I decided to apply to graduate school to work with Matt Lieberman at UCLA. Matt’s lab was full of scientists studying how people understood themselves and others and how they made important decisions.
At the time, it felt like a long shot to connect what happened in a neuroimaging lab to real-world behavior changes outside the lab. But it also felt fundamental: what good was all this research if it couldn’t help us in real life? Luckily, during the years I was in graduate school, we did start to see a connection: a pattern indicating that activity in the brain’s value system could reveal who is more likely to change their behaviors in response to messaging and what kinds of messages were most likely to elicit this kind of activity.
The first work we did in this space focused on sunscreen use. We scanned people's brains while showing them messages about the importance of wearing sunscreen.
The finding was simple: the more activation we saw in a person's value system, the more likely they were to increase their sunscreen use the next week. This suggested that the value system helps guide not only simple choices that people make in the lab but also real-world, consequential behavior change outside the lab.
When I saw the data, I started jumping up and down on the lab couch. One of my friends claims that I screamed, “This is a great day for science!” While I don’t know if nonscientists would be this excited about a data plot, it felt like a big moment. And although this initial study relied on what people told us about their sunscreen use, later studies in the lab I now run at the University of Pennsylvania and others have shown similar results in people being coached on other health habits, where behavior change has been measured more objectively.
When sedentary adults were exposed to messages encouraging them to get more exercise, the activity in their value system corresponded with how much exercise they got later, measured objectively using wrist-worn activity trackers. Similarly, smokers whose value systems responded more strongly to messages encouraging them to quit smoking were significantly more likely to reduce their smoking over the following month, which we confirmed using a device that measures how much carbon monoxide smokers have in their lungs. In fact, our ability to predict how much people would reduce their smoking was twice as good when we included information from both brain responses and self-report surveys as when we included only information from the surveys. This suggests that there was useful information that the value system captured that was not fully captured by surveys alone.
Another current frontier involves understanding when and how people make the kind of deliberate decisions that we’ll mostly focus on in this book, compared with other kinds of decisions. For example, it is increasingly clear that a lot of what humans do is guided by habitual routines – which is not the kind of choice we’ll be discussing. But some of these habits start with deliberate choices, which is our focus. To illustrate this distinction, let’s consider my walk to work.
When I first moved, I wanted to walk to work. I actively chose that. I used my phone to find the shortest route. Over time, it became a habit, something I could do on autopilot. That requires less conscious thought. This book explores what happens in the first type of decisions – when we are more deliberately choosing and setting in motion paths that may (or may not) eventually become habits.
You know, it makes it worthwhile to do an audit every once in a while and to work toward developing an awareness of why we do what we do. What are the everyday choices we’re making? How are we making them? Are there new choices that we can make or ways to choose differently? Are there possibilities we haven’t even considered? And are the choices we are making really serving the lives we want to lead, the people we want to be?
What we do when we ask these questions is bring into play brain systems that can help probe and shape the value system's workings.
The value system works with many other brain systems, including sensory inputs, memory systems, and attention systems. Reasoning and emotion-regulating systems can also change how much weight we give to different inputs. For example, I might give more weight to how tasty or how healthy different foods are, depending on my goals.
In the coming chapters, we'll focus on two brain systems that influence valuation.
The first is the "self-relevance system," which helps us understand ourselves. It's concerned with what we care about, what has happened to us, and what we might do in the future. It creates the feeling that something is "me" or "not me." Jenny used this brain system to believe she could pull off the bank stunt. The guard may have thought about his identity as a helpful person. Whether an option feels like "me" can influence the value calculation.
The second is the "social relevance system," which helps us understand what other people think and feel. This knowledge helps us think through more specific questions, like: Why didn’t you answer my text message? Do you like jokes? How will you respond if I hug you? The human brain has evolved to help us make sense of other people and to evaluate what someone else might think and feel. Jenny was using this brain system when she guessed how the security guard would react. The guard used it when he made his decision to buzz her through.
As a neuroscientist, I find this knowledge empowering. It helps me see how much we can change and grow. Once you understand how the brain assigns value, you can look at decisions with a broader perspective. It helps you explore what possibilities are out there.
The value our brains assign to anything is never fixed. Your behavior isn't determined just by your genes or your personality. It's heavily influenced by context and culture. Leaders at the bank could look at the situation from the guard's perspective and offer solutions that appeal to his identity as a helpful person, while also protecting the bank.
We can influence what our own and others' value calculations focus on, and potentially change the outcome, bringing our daily choices in better alignment with our bigger goals. But to understand what these possibilities are, we first need to understand who we *think* we are, at our core.