Summary: Study reveals how the element of surprise helps facilitate learning and memory retrieval.
Source: University of Manchester
A study by University of Manchester neuroscientists into the effect of surprise on our memory has inadvertently discovered a method which might help us to perform better in exams.
In the study, published in the Journal of Neuroscience, 26 people were shown pictures of objects that were either natural, such as fruit, trees and flowers, or man-made, such as a computer mouse and telephone.
In the study, the scientists trained the participants to expect man-made or natural objects using cues such as a triangle or a square. The whole experiment was then repeated with another 24 people having a functional MRI scan to reveal which regions of the brain were used to learn and retrieve the information.
When an expected event—such as a triangle preceding a man-made object—followed a similar but unexpected event—a triangle preceding a natural object—the participants’ memory was boosted.
The second study in the MRI scanner gave exactly the same behavioral results, and showed activation in the brain’s hippocampus—the memory center, midbrain regions—which release dopamine, and occipital cortex—the vision center. In contrast, a sequence of two unexpected similar events also triggered visual areas in the brain, but did not enhance memory performance.
Lead author Dr. Darya Frank, a cognitive neuroscientist from the University of Manchester, said, “We already know that if expectation is violated before or during learning, it triggers an adaptive mechanism resulting in better memory for unexpected events. This experiment shows how the mechanism is also affected when we are trying to retrieve information.”
The hippocampus encodes—or creates—memories, but also retrieves memories. With only a finite amount of resource to allocate to either, the two mechanisms are in conflict. So when something unexpected happens, our brain focuses on the outside environment so it can learn something new, something it did not initially expect.
The hippocampus encodes—or creates—memories, but also retrieves memories. Image is in the public domain
Scientists already know that surprise turns on the brain’s learning mode, add link however, the current study is the first to investigate how the brain uses the mechanism when we are trying to retrieve information.
Dr. Frank added, “Though our study did not assess the impact of these findings on exam revision and performance, it is logical to see its implications.
“So when the goal is to retrieve information—encountering surprising events like revising in a café or other unfamiliar surroundings would engage an encoding mechanism that may enhance memory for a future exam.
“But the reverse is also true: when trying to remember something already learned during the exam itself, a familiar and expected environment could be helpful, and support retrieving information from memory.”
Experiencing Surprise: The Temporal Dynamics of Its Impact on Memory
To efficiently process information, the brain shifts between encoding and retrieval states, prioritizing bottom-up or top-down processing accordingly. Expectation violation before or during learning has been shown to trigger an adaptive encoding mechanism, resulting in better memory for unexpected events.
Using fMRI, we explored (1) whether this encoding mechanism is also triggered during retrieval, and if so, (2) what the temporal dynamics of its mnemonic consequences are. Male and female participants studied object images, then, with new objects, they learned a contingency between a cue and a semantic category. Rule-abiding (expected) and violating (unexpected) targets and similar foils were used at test.
We found interactions between previous and current similar events’ expectation, such that when an expected event followed a similar but unexpected event, its performance was boosted, underpinned by activation in the hippocampus, midbrain, and occipital cortex. In contrast, a sequence of two unexpected similar events also triggered occipital engagement; however, this did not enhance memory performance.
Taken together, our findings suggest that when the goal is to retrieve, encountering surprising events engages an encoding mechanism, supported by bottom-up processing, that may enhance memory for future related events.