As you scroll through this article, your brain is hard at work creating the mental world you live in. You probably have a seamless sense that you’re embedded in a world full of other people, objects, and your own thoughts.
By the time you’ve read this sentence, your brain will have rapidly decoded data in its sensorium (the part that receives and interprets sensory information) – turning the shapes on this screen into a voice in your head. But that’s not all. It’s also making deeper, faster judgments.
For instance, though we’ve never met, your brain probably made some snap assumptions about me, especially after I used a word like sensorium. (Academic? Yes. Pompous? I’ll let you decide.)
Or perhaps it triggered a more inward-looking response: confidence or uncertainty about what sensorium really means.
As a psychologist and neuroscientist, my job is to understand how the brain pulls off this remarkable trick – how it builds the illusion of an external world.
And, with my colleagues, I think we’ve discovered a radical answer – your brain is like a scientist.
Just as scientists build theories to make sense of the world, so your brain generates its own hypotheses to interpret reality.
This may explain why your brain’s work feels so fast and effortless. But while this method is efficient, it comes at a cost: it means our brains can easily misperceive or misbelieve.
Each of us lives in a version of reality shaped by our own assumptions and predictions. Becoming aware of the tricks our minds play can reshape how we understand ourselves, and also help us better relate to those who see the world differently.
Here are the top ways your brain builds your version of reality – and how to turn them to your advantage.
1. Your world is a hallucination
We usually think our brains give us a roughly accurate picture of the world. After all, we assume that ‘seeing things’ or ‘hearing things’ means we’ve lost our minds. But the latest research suggests that’s not quite true.
In fact, all of us are hallucinating all the time – and the theories our brains come up with shape what we perceive.
You can see this in the illusion on the cover of my book below. Though most people see the apple as red, it’s actually grey.
You see red because your brain has a theory about apples and what colour they’re supposed to be. It’s this theory you see projected, not the actual pixels on the screen.
If we put you in an MRI scanner, we can see your brain creating its own assumptions and expectations even when nothing’s there.
For example, if we show you a photo with a big chunk missing, the visual areas of your brain that should be inactive light up with neural patterns that resemble what your brain thinks should be there. We can see, in real time, your brain filling in the blanks on the canvas of visual space.
This process is usually helpful – but it does give our brains a built-in tendency to invent.
Realising that all of us can see or hear things that aren’t there offers a fresh perspective on more serious hallucinations – like those experienced by people with psychotic illnesses, or psychics who report ‘hearing’ supernatural voices.
Scientists think that people with these vivid hallucinations may be more prone to having their assumptions and theories spill into perception.
Importantly, there seem to be different brain networks involved in hallucinating and in becoming mentally unwell.
So, if you hallucinate, that doesn’t mean anything is wrong with your perception. Hallucination is not a glitch – it’s a core feature of how the brain works.
2. You don't really listen to what other people say
Have you ever grabbed the mic at karaoke, watched the lyrics scroll past, and realised you’ve been mishearing a song for months – or even years? You’re not alone.
Many people experience so-called ‘mondegreens’ – misheard lyrics like Nirvana’s “here we are now, in containers” or Elton John’s “count the headlice on the highway”.
These misperceptions happen because we rarely hear exactly what people say – only our brain’s best guess at what they probably meant.
It might sound rude, but this is because your brain doesn’t hang around for people to finish their sentences.
We know this because, when researchers record people talking across a whole host of different languages, the average gap between turns in conversation is astonishingly short – around 200 milliseconds (a fifth of a second).
To keep up, your brain must jump ahead – generating hypotheses about how a sentence will end before the speaker gets there. We can even see this happen in the brain as you listen to natural speech.
If you hear a sentence like “in the hospital there is a newborn…”, an MRI scan will show your brain activating a pattern resembling the word ‘baby’ before it’s actually said.
This doesn’t just save time – it helps us decode speech that might otherwise be unclear or ambiguous. You can observe this for yourself by listening to this audio clip...
Most people hear this as strange and garbled – robotic whistles with only faint hints of recognisable speech.
In fact, it’s a degraded recording of human speech (in this case created by Matt Davis at the University of Cambridge). Before degrading, the original sounded like this...
Here’s the strange part: if you now go back and listen to the first clip again, it suddenly sounds crisp and clear.
Now that your brain has the right theory about what the speech contains, it reprocesses the noise and pulls out the message. Your brain’s predictions are fundamentally altering how you hear – and how you understand.
Again, most of the time, this helps us. But if your brain has the wrong expectations, it can lead you astray. (Something to remember before your next karaoke night.)
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3. You're not really in control
Our brains often mislead us about how much control we have over the world. One striking example comes from what psychologists call ‘illusions of control’ – where we feel responsible for things we can’t influence.
Take placebo buttons. In many cities, there are pedestrian crossings, elevators and even office thermostats with buttons that do absolutely nothing – the real systems are in fact run by computers or timers. But people press these buttons anyway, not realising they’re ineffective.
They feel they’re stopping cars or changing the temperature simply because they expect they can.
But while these false feelings of control are fascinating, perhaps more troubling is the opposite misperception: ‘illusions of passivity’ – where we feel less responsible than we actually are.
These illusions become dangerous in social settings, such as when people are ‘just following orders’. In one study, researchers looked at what happens in the brain when someone harms another person by choice, compared to when they’re ordered to do so.
If a volunteer chooses to (mildly) electrocute a partner for a small reward, their brain lights up in response to the noise of the shock – a sign they’re registering the consequences of their actions. But when they are ordered to administer the same shock, the brain’s response is muted.
It’s as if, by surrendering responsibility, the brain literally tunes out the effects of its own actions.
The good news is that this isn’t fixed. We can train ourselves to take greater ownership – and experience a more accurate sense of control. In another version of the same shock experiment, researchers worked with trainee soldiers at a Belgian military academy.
Despite being trained to follow orders, these soldiers processed their actions differently because they are also trained to take responsibility for their actions.
So, even when they were ordered to cause harm, their brains still showed signs of agency and consequence – their neural activity reflected awareness of what they were doing, whether the choice was freely made or commanded.
Military training might not be for everyone, but these results reveal something important about us all: our sense of control is filtered through our brain’s theories. We don’t feel as much control as we have, but as much as our brain thinks we should.
As these soldiers show, it’s possible – through experience and social learning – to reshape those beliefs, and with them, our sense of how much our actions really matter.
4. Your body language is actually a 'body dialect'
You may think you’re pretty good at reading body language. If one co-worker is smiling and skipping down the hall while another shuffles by, isn’t it obvious who got the promotion?
But emotions aren’t beamed straight from one brain to another. Consider the illustration below, from a study where psychologists showed participants photographs of tennis players – one seemingly triumphant, the other defeated.
But there’s a twist: the faces are identical, digitally copied and pasted onto different bodies. Your brain fills in the emotional meaning based on the posture it expects to see with that face.
This tells us something crucial: we don’t see emotions directly. We interpret emotions based on the whole picture – and our own expectations.
We tend to assume other people express emotions the same way we do, but we usually only get it right with people who move with a similar rhythm to our own.
This explains why studies find we are more accurate at reading the emotional states – happiness, sadness or anger – of people with a similar spontaneous motor tempo (the pace of our movements).
People who walk fast are also likely to tap or gesture quickly, and that rhythm becomes a kind of personal ‘dialect’ for expressing emotion.
These mismatched dialects can explain many everyday misunderstandings between friends, partners, co-workers or family. They may also help explain the classic tensions between teenagers and their parents.
As we age, our body rhythms slow down, which means we express emotions differently. That means each age group is tuned in to the rhythms of their peers – so teens often seem overly exuberant or aggressive to adult eyes, while adults might appear gloomy or withdrawn to teens.
Our brains then give us the impression that teenagers are overly emotional, and our parents are unreasonably upset with us – enough to make parents and their children clash.
The same logic can help us better understand miscommunications in a neurodiverse world. For years, scientists assumed that autistic people struggled to understand others. But it turns out that miscommunication goes both ways.
For instance, studies show that autistic people tend to move differently – often with more sudden or accelerated gestures.
The same studies show that these differences persist even when autistic participants are asked to convey more complex emotions, like when acting out a story involving persuasion or deception.
In lab settings, autistic participants sometimes struggle to decode the intended thoughts and feelings of neurotypical partners – but neurotypical participants also struggle to read autistic individuals.
This makes perfect sense if we think that everyone is interpreting others through their own bodily lens. It doesn’t always make sense to say that one person is ‘good’ at empathy and another is ‘bad’.
Instead, it all comes down to how well another person fits the prism our brains have built up for us already.
5. What you see in the mirror is your brain's theory of itself
We don’t just use our brains to look outwards as we make sense of the physical world or other people. We also look inwards.
But making sense of ourselves can be just as error-prone as reading other people. In fact, your self-image is shaped by your brain’s internal theory of who you are.
At the heart of this is confidence: the subjective sense of conviction in your decisions and actions. Yet it’s surprisingly difficult for the brain to work out how confident or uncertain you should really feel. Because of this, it leans heavily on your past experiences and expectations.
In our experiments, for example, we’ve found people feel more confident in contexts where they’ve been successful in the past, and more uncertain in situations where they’ve previously struggled, even when their actual performance is completely identical.
In other words, when we introspect, we feel the confidence our brain expects us to feel, regardless of our true talent, potential or skill.
In many ways, this is much like the other illusions your brain creates – but with often worse and longer-lasting consequences.
These introspective biases can become self-perpetuating, leaving you stuck with a particular view of yourself.
If you’ve been lucky in the past, your brain will build optimistic expectations into your self-image, fuelling the confidence you need to strive and succeed.
But if you’ve been unlucky, your brain may bake in more pessimistic predictions into your experiences, making you feel uncertain, incapable, and sapping your motivation to try again. This could explain why success so often does breed success.
One study found that scientists who only barely won their first research grant went on to accumulate more funding over their careers, compared to peers who were narrowly pipped at the first post.
But this gap between the ‘lucky winners’ and the ‘unlucky losers’ was mostly down to effort, rather than talent – with the losers often deciding not to apply again.
We can think this happens precisely because these strokes of fortune entrench themselves in our brain’s models of what we can and can’t do.
Findings like this teach us the important lesson that our feelings of subjective confidence (or lack of it) can be misleading.
This sheds light on conditions like depression, which some psychologists believe is fuelled by a widespread drop in subjective confidence, even when our objective skills and abilities remain intact.
Depressive thoughts and feelings could be taking hold precisely when our brains get stuck with a pessimistic theory of who we are. Crucially, though, understanding this fact helps us to break the cycle.
By recognising that our brains aren’t always right about us – and that it’s worth persevering anyway – we open ourselves up to new experiences and potential successes that update our model of ourselves. And with it, a different, more accurate sense of who we really are.
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