Every moment, the brain takes in far more information than it can process on the fly. In order to make sense of it all, the brain constantly makes predictions that it tests by comparing incoming data against stored information. All without us noticing a thing.
Simply imagining the future is enough to set the brain in motion. Imaging studies have shown that when people expect a sound , the brain generates an anticipatory signal in the sensory cortices.
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This ability to be one step ahead of the senses has an important role in helping us understand speech. 鈥淭he brain is continuously predicting the sounds, words and meanings that people are trying to produce or communicate,鈥� says Matt Davis at the MRC Cognition and .
鈥淲e only notice an object once our unconscious has calculated its importance鈥�
Studies have also shown that the brain can use one sense to inform another. When you hear a recording of speech that is so degraded it is nearly unintelligible, the words sound clearer if you have . 鈥淭he sensory parts of the brain are comparing the speech you鈥檝e heard to the speech you predicted,鈥� says Davis.
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Not only do we make hypotheses about external information, our brains also make predictions on the basis of emotional signals coming from the body. Moshe Bar, a neuroscientist at Bar-Ilan University in Israel goes so far as to suggest that we only consciously recognise an object once our unconscious mind has calculated its importance based on what our senses and emotional reaction are saying. The conscious fear of a snake on a hiking trail comes after the brain has processed the shape and .
Making predictions does have its downsides, however. Incorrect inferences, reinforced by repetition can be hard to reverse, which is why when you learn the wrong lyrics to a song, it can be difficult to stop hearing them. Stereotyping is a more troublesome example of the same thing. While it can be useful to recognise that the dangers of things like snakes and fires are relatively constant, when it comes to human interactions, it can lead to negative biases and discrimination. 鈥淪tereotypes and prejudices are predictions working as they do with everything else, but [in a way] that is not desirable,鈥� says Bar.
Some neuroscientists also believe that the hallucinations experienced in psychosis are the result of expectations gone awry. In one recent study, people who were more prone to psychotic experiences were better at seeing hidden shapes in images that had been digitally degraded. The researchers speculate that this could mean their brains jump to conclusions faster and rely less on evidence coming in from the senses.
Despite its flaws, prediction is hugely beneficial. 鈥淚magine that our brain didn鈥檛 work like that,鈥� says Bar. 鈥淓very snake you see you鈥檇 have to learn afresh. Every fire you鈥檇 have to touch and burn yourself.鈥�
This article appeared in print under the headline 鈥�6. Predict the Future鈥�
