New research suggests bouts of forgetfulness could be caused by a safety mechanism in the brain designed to make sure we’re not overloaded with information. In other words, it’s a healthy part of the brain’s operation.

That might come as a relief if you’re always forgetting where you left your house keys, but it could also teach us more about how the brain operates, something scientists are still trying to figure out.

According to the two researchers from the University of Toronto in Canada, memory isn’t intended to help transmit the most accurate information, but rather the most useful information that can help us make smart decisions in the future.

“It’s important that the brain forgets irrelevant details and instead focuses on the stuff that’s going to help make decisions in the real world,” explains one of the researchers, Blake Richards.

Richards and his colleague Paul Frankland reviewed previously published papers taking different approaches to the idea of memory. Some looked at the neurobiology of remembering, or persistence, while others looked at the neurobiology of forgetting, or transience.

“We find plenty of evidence from recent research that there are mechanisms that promote memory loss, and that these are distinct from those involved in storing information,” says Frankland.

The researchers found evidence of the deliberate weakening of the synaptic connections between neurons that help to encode memories, as well as signs that new neurons overwriting existing memories, to make them harder to access.

So why is the brain spending time trying to make us forget? Richards and Frankland think there are two reasons.

One, forgetting helps us adjust to new situations by letting go of memories we don’t need – so if your favourite coffee shop has moved to the other side of town, forgetting its old location helps you remember the new one.

Second, forgetting allows us to generalise past events to help us make decisions about new ones, a concept known in artificial intelligence as regularisation. If you just remember the main gist of your previous visits to the coffee shop rather than every little detail, then it’s less work for your brain to work out how to behave the next time you go in.

“If you’re trying to navigate the world and your brain is constantly bringing up multiple conflicting memories, that makes it harder for you to make an informed decision,” says Richards.

The researchers also think the amount of forgetting we do could depend on the environment, with a faster pace of change requiring a faster pace of forgetting too.

One experiment mentioned in the paper that Frankland was also a part of involved mice looking for a maze. When the location of the maze was moved, mice that were drugged to forget the old location found the new one more quickly.

There’s no doubt forgetting information we need to remember too often is a frustrating experience – and maybe the sign of more serious problems – but the new research suggests a certain level of forgetfulness is actually a built-in mechanism designed to make use smarter.

Maybe that’s something to mention at the next trivia night at your local bar.

“We always idealise the person who can smash a trivia game, but the point of memory is not being able to remember who won the Stanley Cup in 1972,” says Richards.

“The point of memory is to make you an intelligent person who can make decisions given the circumstances, and an important aspect in helping you do that is being able to forget some information”.

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