Below, Daniel Yon shares five key insights from his new book, A Trick of the Mind: How the Brain Invents Your Reality.
Daniel is a psychologist, neuroscientist, and Director of the Uncertainty Lab at Birkbeck, University of London. He studies how our brains build models of ourselves and the world around us, and has written on this topic for Aeon and Psyche, as well as been published in a number of his field’s leading journals.
What’s the big idea?
Your brain is like a scientist, constantly trying to build its own theories and models about the world, other people, and itself. Understanding the mechanisms by which our minds build our perceptions can transform how we approach mental health, neurodiversity, and relationships.
1. Your brain invents the world around you.
Perceiving the world around us usually feels effortless. You point your eyes out in front of you and see a visual scene, or you open your ears and hear a voice trailing into them. It’s tempting to think that these sensing organs are like instruments or sensors, like a camera or a microphone, just taking the signals in. But the latest neuroscience and psychology suggest that this is only half the story.
The scientist sitting inside your skull takes all these measurements from your eyes and ears, but combines them with its own theories and hypotheses about what’s happening in the outside world. In this laboratory inside your head, your brain comes up with its own interpretation of what’s happening in the world, and what should and shouldn’t be there.
This is usually a helpful process, but perceiving the world through the filter of these theories can leave us misunderstanding and misperceiving. One way you can observe this process yourself is when you mishear song lyrics—like people who hear Bob Dylan sing “the ants are my friends” when the actual lyrics are “the answer, my friend.” These mistaken interpretations become the reality you experience.
Thinking this way about perception can offer a whole new perspective on some unusual experiences, ranging from spiritual experiences of medieval mystics to the voices heard by modern-day psychics or the hallucinations that affect people experiencing psychosis. These phenomena can arise when our brains rely too much on their own theories as we perceive the world, leading our expectations to leak into our experiences.
Perceiving in this way doesn’t make you mad. Rather, thanks to the scientists in our skulls, all of us are hallucinating, constructing the world we live in, moment by moment, all the time.
2. We don’t all have the same body language. We have body dialects.
We don’t just need these theories and hypotheses to construct the world around us. Our brain also needs them to read the hearts and minds of other people. We can never directly experience the world from someone else’s perspective. Other people are more like other planets.
Scientists looking for life on distant planets can’t go visit and experience what the atmosphere is really like. We point satellites into the galaxy and look for signs of life that we can decode from the surface. In much the same way, when we try reading the minds of other people, all we have to go on is the observable stuff on the surface: things they say, how they move.
“Other people are more like other planets.”
It might seem obvious that we can read body language to work out what others think and feel. But there is no single body language. All of us have our own body dialect, tuned to the way that we move and express ourselves. This gives our brain a theory of what certain emotional or mental states should look like. But it means we will struggle to read the minds of people who don’t express themselves like we do. This can be important in lots of different contexts.
As we grow up, our body movements change—children and adolescents move faster than mature adults—and that means that emotional expressions literally look different. As parents try to understand their teenagers, and vice versa, their brains can read each other through inappropriate theories, making it possible to see signs of anger or upset that aren’t there.
This is important for understanding neurodiversity too. Studies show that people with autism have subtle differences in their body movements. While we might traditionally think that these groups are worse at reading minds than neurotypicals, once we account for these differences in expression a different picture emerges. Autistic people might struggle to read the minds of neurotypicals, but neurotypicals also struggle to decode the thoughts and feelings of autistic people. Understanding or misunderstanding is about how we align the theories in our minds.
3. When we look in the mirror, we see our brain’s theories reflected.
In 2008, Douglas Prasher got the news that the Nobel Prize in Chemistry would be awarded for his discovery of green fluorescent protein—an innovation that let scientists study the inner workings of tiny cells in hitherto unimaginable detail. Unfortunately, that Nobel Prize wouldn’t be going to him. After a string of misfortunes, Prasher left science altogether. By the time the call from Sweden came, he was working as a courtesy car driver for a Toyota dealership in Alabama.
How can it be that a scientist can have a genuinely Nobel-winning idea, but not the confidence and self-belief to pursue it? How can our minds and brains get our self-images so wrong? Introspection is a serious challenge for brains like ours. We must rely on our own hypotheses and expectations to make sense of our own abilities and talents. These theories are built on our past experiences: past successes give us optimistic expectations about what we can achieve in the future; past failures leave us pessimistic.
“Introspection is a serious challenge for brains like ours.”
This way of thinking can explain why scientists like Prasher—after strokes of bad luck—end up with negative self-images that clip the wings of ambition. But these ideas can have a deeper significance, too. Psychologists and neuroscientists have begun wondering whether mental illnesses, like depression, could arise when brains get stuck with pessimistic theories about what we can and can’t achieve. Our past experiences can cast a long shadow on who we think we are and what we think we are capable of.
4. Happiness has more to do with learning than earning.
In the 1970s, British operatives were dispatched on clandestine missions behind the Iron Curtain. But these operatives weren’t government spies, with suitcases stuffed full of state secrets. These agents were British academics, with briefcases filled with a more unusual kind of contraband: lectures on modern philosophy.
In what became known as the underground university, students in Communist Czechoslovakia secretly studied for philosophy degrees under the noses of the state’s Secret Police—who could have imprisoned them for following their curiosity. But what makes us think it’s worth risking our liberty or lives to satisfy our curiosity? Where does this drive for curiosity come from?
Thinking of your brain as being like a scientist offers a new perspective on what we value and why. Though much has been written about the brain’s greedy midbrain circuitry and the way our brains will do anything to get a dopamine hit, the latest science suggests a different picture. Of course, we have basic drives for food, money, or sex. But evolution has also made our brains treat knowledge and information as a currency.
Because our thirst for knowledge latches onto the same brain circuits as actual thirst, our brains become curious scientists, with a drive to understand the world and our place in it. This can explain some of the strangest findings in economics and psychology, like the fact that massive increases in salary don’t reliably translate into happiness, or that moment-to-moment well-being is highest when we are learning something new and unexpected. Thanks to the scientist in your skull, happiness is more about what you learn than what you earn.
5. Your brain controls its own paradigm shifts.
The COVID-19 pandemic saw a dramatic spike in the number of people endorsing bizarre conspiracy theories—and not just ones about the pandemic. People became more likely to believe in political conspiracies, like the QAnon movement. How is it that perfectly normal people with perfectly normal minds can come to think the unthinkable?
If your brain is a scientist, building up theories and paradigms to understand the world, it also has to recognize when those paradigms should shift. The latest science tells us that your brain solves this problem by listening to the uncertainty and volatility in the outside world. If the environment seems stable, we want to stick with the theories we already have. But if the world seems to be changing, we should want our minds to change with it.
“Living through periods of uncertainty leads to a spike of activity in the brain circuits that track volatility.”
This process usually serves us well, but it can make our minds vulnerable when the world seems to be shifting. Living through periods of uncertainty leads to a spike of activity in the brain circuits that track volatility. This loosens old theories throughout the brain, making it easier for them to be replaced by something new. This helps us adapt our minds to new surroundings, but it also makes us malleable to whatever message we sample next—even if it comes from a conspiracy theory. An open mind can be a dangerous thing.
Knowing more about these mechanisms reveals new ways that we might control how the paradigms in our brains do and don’t shift. There are already drugs (like Ritalin or propranolol) that seem to control how much we can update and change our minds.
But even if these pills can alter the theories and hypotheses concocted by that scientist in your skull, would you really want to take them? Our brain’s paradigms might be a source of bias, misperception, and misunderstanding. But they are also the key ingredient that makes perception and belief possible. Just like the theories in science, the theories in your brain aren’t forever stuck. And just like science itself, your mind is a work in progress.
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