The reason scientists still don't understand what emotions really are © Getty Images

We don’t understand how emotions work. A neuroscientist explains why we often get it wrong

How do you feel? Are you anxious about something? Or scared? Why do you feel this way and where do all these sensations come from?

Emotions are your brain’s best guesses of what your bodily sensations mean, guided by your past experience. Your brain constructs these guesses in the blink of an eye – so rapidly, in fact, that emotions feel like uncontrollable reactions that happen to you, when emotions are actually made by you.

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For a long time, scientists were sure that emotions were caused by dedicated brain circuits – a circuit for happiness, one for fear, another for anger and so on – that automatically triggered a specific pattern of facial expression, bodily state and physical action.

For example, if you saw a snake, a supposed ‘fear circuit’ would activate, causing your eyes to widen, your heart to race and your body to prepare to flee. A given emotion was thought to be a chain reaction of coordinated events and it occurred reliably enough to indicate when a person was experiencing it.

Nevertheless, most of the scientific evidence doesn’t support this view. It suggests instead that each instance of emotion is a whole-brain event. Your brain uses your past experiences to combine information from your body, such as a pounding heart, with information from the world, like the fact that you’re waiting in a doctor’s office for test results, to construct an emotion, such as anxiety.

In a different situation, such as watching your lover walk into the room, your brain might construct an instance of excitement or lust from exactly the same pounding heart. Or if you’re exercising, your brain might transform that pounding into an instance of fatigue. The meaning that your brain makes helps it plan your body’s next action to keep you alive and well.

Even with this mounting evidence, the science of emotion is full of confusion. Some scientists still study brain circuits for actions, such as freezing in place, and claim that they’re studying the circuits for emotion. Hundreds of studies conclude that people around the world express emotion with the same facial movements, even though most of these studies use a fragile experimental method that fails to replicate when tweaked.

Companies claim to have machine learning algorithms to detect emotion from smiles and scowls, but they’re detecting muscle movements, not the emotional meaning of those movements in context. Data show, for example, that people who live in large-scale, urban cultures scowl in anger less than 30 per cent of the time, so for the other 70 per cent they’re doing something else with their faces in anger.

And people scowl for many reasons besides anger – they might be concentrating hard or have gas. The evidence for universal expressions of emotion is even weaker in small-scale, remote societies. Therefore, scowling isn’t the universal expression of anger, just one expression among many.

This muddle trickles down into the popular press, which is why you see news stories that mice have emotional facial expressions (they don’t), that a brain region called the amygdala is the location of fear (it’s not) and that AI systems can read your emotions (they can’t).

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