We CAN predict the future (a bit): Why the brain knows what's going to happen before it does



People subconsciously make thousands of tiny predictions each day, whether it's contemplating when a bus will arrive, who is knocking on the door or if a dropped glass will break.

Now scientists are beginning to unravel how the brain is such a surprisingly accurate fortune-teller - but only when it comes to mundane events.



Researchers at Washington University in St Louis focused on the mid-brain dopamine system (MDS), which provides signals to the rest of the brain when unexpected events occur.

Each of us makes thousands of tiny predictions, such as contemplating when a bus will arrive, every day. Scientists are now beginning to unravel how the brain is such a surprisingly accurate fortune-teller

Using functional MRI (fMRI), they found that this system encodes prediction error when viewers are forced to choose what will happen next in a video of an everyday event.

They found that between 80 and 90 per cent of viewer predictions were correct, depending on when the footage was stopped.



Lead researcher Jeffrey Zacks said predicting the near future is vital in guiding behaviour and is a key component of theories of perception, language processing and learning.



He said: 'It's valuable to be able to run away when the lion lunges at you, but it's super-valuable to be able to hop out of the way before the lion jumps.



'It's a big adaptive advantage to look just a little bit over the horizon.'

The research will also help those in the early stages of neurological diseases such as schizophrenia, Alzheimer's and Parkinson's, Professor Zacks said.



The scientists tested healthy young volunteers who were shown films of everyday events such as washing a car, building a Lego model or washing clothes. The film would be watched for a while, and then it was stopped.



Participants were then asked to predict what would happen five seconds later when the film was re-started by selecting a picture that showed what would happen.



Half of the time, the movie was stopped just before an event boundary, when a new event was just about to start. The other half of the time, the film was stopped in the middle of an event.



The researchers found that participants were more than 90 per cent correct in predicting activity within the event, but less than 80 per cent correct in predicting across the event boundary. They were also less confident in their predictions.



'Successful predictions are associated with the subjective experience of a smooth stream of consciousness'

Professor Zacks said: 'This is the point where they are trying hardest to predict the future. It's harder across the event boundary, and they know that they are having trouble.



'When the film is stopped, the participants are heading into the time when prediction error is starting to surge. That is, they are noting that a possible error is starting to happen.



'And that shakes their confidence. They're thinking, "Do I really know what's going to happen next?"'



In the functional MRI experiment, the researchers saw significant activity in several mid-brain regions, among them the substantia nigra - 'ground zero for the dopamine signaling system' - and in a set of nuclei called the striatum.



The substantia nigra is the part of the brain most affected by Parkinson's disease, and is important for controlling movement and making adaptive decisions.



Brain activity in the experiment was revealed by fMRI at two critical points - when subjects tried to make their choice, and immediately after feedback on whether their answers were correct or incorrect.

Professor Zacks said: 'When we watch everyday activity unfold around us, we make predictions about what will happen a few seconds out. Most of the time, our predictions are right.



'Successful predictions are associated with the subjective experience of a smooth stream of consciousness.



'But a few times a minute, our predictions come out wrong and then we perceive a break in the stream of consciousness, accompanied by an uptick in activity of primitive parts of the brain involved with the MDS that regulate attention and adaptation to unpredicted changes.'