We can only recall a very small proportion of the memories we make each day.
Research finds that rewarding memories are recalled preferentially because the brain replays them automatically when we are at rest.
The brain prioritises rewards as they are important cues about future behaviour.
Professor Charan Ranganath, one of the study’s authors, said:
“Rewards help you remember things, because you want future rewards.
The brain prioritizes memories that are going to be useful for future decisions.”
In the study people looked at various pictures of objects on different backgrounds.
Some were associated with a higher reward for later recall.
When given a surprise memory test afterwards, people were better at remembering the objects with higher levels of reward.
Dr Matthias Gruber, one of the study’s co-authors, said:
“Also, when an object was associated with high reward, people remembered better the particular background scene that was on the screen during scanning.”
The interesting finding came from a series of brain scans conducted just after people had looked at the objects, while resting.
These suggested that people were replaying the high-reward memories to help mentally fix them in place.
Their brains were doing this automatically, without volition, since they didn’t know a test was coming.
The people who replayed the memories the most did the best on the surprise test.
Professor Ranganath said:
“It speaks to a memory process that is normally hidden from us.
Are you remembering what you really need to know?
It could depend on what your brain does while you are at rest.”
The study was published in the journal Neuron (Gruber et al., 2016).
