Forgetting is brain’s trick to make better decisions, study finds

There seems so much more to remember nowadays — and thus, naturally, more to forget. The internet is full of useful snippets to fill up our brains, and then there’s social media forcing us to remember the name, face and associated memories of people we met once a decade ago.

This has been my theory and excuse for many years. But research from the University of Toronto has found it might not be our fault if we become more forgetful; it is our brain helping us to forget in order to improve decision-making.

I’m suspicious of research telling me exactly what I want to hear. In 2014, a study “found” chocolate made you lose weight — music to the ears of chocolate lovers around the world. It sounded too good to be true, and it was. It was a journalist publishing a paper that had not been peer reviewed to show how easy it was to get false research into the media.

This latest research about forgetting makes sense though, and has been published in a peer-reviewed journal, Neuron. The brain needs useful information to make decisions. Too much information compromises the ability to decide, and so we need to be able to forget.

The paper’s authors, academics at the University of Toronto and The Hospital for Sick Children, note that historically, the focus of memory research has been on remembering, or “persistence”. But now researchers are including the study of “transience”, the neurobiology of forgetting.

“The goal of memory,” they write, “is not the transmission of information through time, per se. Rather, the goal of memory is to optimise decision-making.”

They cite the example of Patient S, whose case was documented by Russian neuropsychologist Alexander Luria. Patient S, who was later revealed to be Russian journalist Solomon Shereshevsky, had a super-human memory. He could listen to a speech without taking a single note and could then reproduce it verbatim. The only way he could forget things was if he actively forced himself to.

But every superpower has its downside: because he couldn’t forget, Patient S could not generalise; each individual event or thing he learnt was distinct in his mind.

We need to be able to generalise to make decisions. “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 a co-author of the paper, Prof Blake Richards.

“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,” he says. “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.”

THE GOAL OF MEMORY IS NOT THE TRANSMISSION OF INFORMATION THROUGH TIME, PER SE. RATHER, IT IS TO OPTIMISE DECISION MAKING

Previous research by co-author Paul Frankland showed the brain actively makes us forget.

In 2013, in the journal Trends in Neuroscience, Frankland and co-authors propose that the birth of brain cells in the hippocampus is a natural decay process that clears away old memories. The hippocampus is thought to be the seat of memory in the brain. They argue this is why so few memories of childhood remain — it’s a time when the brain is a cauldron of neurogenesis, experiencing and forgetting with abandon.

However, it is a bad idea to tell someone you have met four times and whose name you still can’t remember that research says you forgot it because it didn’t seem like useful information to make decisions in the future.