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Study finds our 'stubborn brains' use past experiences to shape how we perceive the present

The research is important for neuroscientists and psychologists trying to understand how experiences from our past shape our predictions about the future.

An illustration and outline of a woman's head and face side on, through which the brain can be seen firing signals that have formed a webbed sphere around the head.

A new study led by researchers at Birkbeck has found that the human brain rapidly forms beliefs about what to expect in the world around us, and these predictions continue to shape activity in our brains even when the world begins to change.

It's common to think that what we perceive and experience just depends on the information received by our senses, such as what our eyes can see or ears can hear. But in recent years psychologists and neuroscientists have become interested in the idea that the brain is a 'prediction machine' that constantly combines information from our senses with the brain's expectations about what the world is like. Dr Daniel Yon and colleagues aimed to explore an unanswered question about this 'predictive brain' theory, by investigating how these predictions are formed how our expectations update when the world begins to change.

The research team included Birkbeck's Dr Daniel Yon and Prof Clare Press. In the study, the researchers showed volunteers patterns of visual sensations, allowing the volunteers to learn that certain images would be expected and others unexpected. The research team then scanned the volunteers' brains and measured how these learned expectations impacted what happened in visual regions of the brain when observers saw patterns that were expected and ones that weren't.

The study found that the learned beliefs of the volunteers changed patterns of activity in the primary visual cortex, an area of the brain that is important for determining what we see. Most importantly though, the team discovered that these expectations continued to sculpt brain activity even though the environment had dramatically changed – and previously 'expected' events were no longer very likely to happen. This shows that our beliefs continue to shape activity in our brains, even when our old expectations no longer come true.

Dr Yon commented: "Understanding how our brains form these predictions – when they change and when they don't - is important for neuroscientists interested in how we integrate our experiences in the past with our experiences in the present. But understanding this kind of 'stubbornness' in the brain, could also be important for understanding unusual mental pathologies – like delusional thinking. We can imagine that stubborn unreliable beliefs formed in the past might continue to colour the way we perceive the present, even when these beliefs no longer coincide with what the world is really like."

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