Every day we make thousands of tiny predictions – when the bus will arrive, who is knocking on the door, whether the dropped glass will break.
Now, in one of the first studies of its kind, researchers at Washington University in St. Louis are beginning to unravel the process by which the brain makes these everyday prognostications.
While this might sound like a boon to day traders, coaches and gypsy fortune tellers, people with early stages of neurological diseases such as schizophrenia, Alzheimer’s and Parkinson’s diseases could someday benefit from this research. In these maladies, sufferers have difficulty segmenting events in their environment from the normal stream of consciousness that constantly surrounds them.
The researchers focused on the mid-brain dopamine system (MDS), an evolutionarily ancient system that provides signals to the rest of the brain when unexpected events occur.
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.
Predicting the near future is vital in guiding behavior and is a key component of theories of perception, language processing and learning, says Jeffrey M. Zacks, PhD, WUSTL associate professor of psychology in Arts & Sciences and lead author of a paper on the study in a forthcoming issue of theJournal of Cognitive Neuroscience.
“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,” Zacks says. “It’s a big adaptive advantage to look just a little bit over the horizon.”
Zacks and his colleagues are building a theory of how predictive perception works. At the core of the theory is the belief that a good part of predicting the future is the maintenance of a mental model of what is happening now.
Now and then, this model needs updating, especially when the environment changes unpredictably.
“When we watch everyday activity unfold around us, we make predictions about what will happen a few seconds out,” Zacks says. “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.”
Zacks tested healthy young volunteers who were shown movies of everyday events such as washing a car, building a LEGO model or washing clothes. The movie would be watched for a while, and then it was stopped.
Participants then were asked to predict what would happen five seconds later when the movie was re-started by selecting a picture that showed what would happen, and avoiding similar pictures that did not correspond to what would happen.