How Forgetting Makes You Smarter
By Lila Sahija
We’re always making excuses for our forgetfulness, and we tend to think of forgetting as a sign of a scatter-brained or disorganized person. But if you’re wondering what causes you to forget things, new research on how the brain processes and stores memories explains why forgetting is a positive thing.
According to a new review paper from Paul Frankland, a senior fellow in CIFAR’s Child & Brain Development program, and Blake Richards, an associate fellow in the Learning in Machines & Brains program, our brains are actively working to forget. In fact, the two University of Toronto researchers propose that the goal of memory is not to retain as much information as possible, but to guide and optimize intelligent decision making by making sure the brain only stores valuable information.
“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,” says Richards.
The review paper, published this week in the journal Neuron, looks at the literature on remembering, known as persistence, and the newer body of research on forgetting, or transience. Recent research on how memory works supports this idea that forgetting is just an vital a part of our brain’s memory functions as remembering.
“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.
One of these mechanisms is the weakening or elimination of synaptic connections between neurons in which memories are encoded. Another mechanism, supported by evidence from Frankland’s own lab, is the generation of new neurons from stem cells. As new neurons integrate into the hippocampus, the new connections remodel hippocampal circuits and overwrite memories stored in those circuits, making them harder to access. This may explain why children, whose hippocampi are producing more new neurons, forget so much information.
It may seem counterintuitive that the brain would expend so much energy creating new neurons at the detriment of memory. Using principles from artificial intelligence (AI), Frankland and Richards argue that the interplay between remembering and forgetting allows us to make more intelligent memory-based decisions.
It does so in two ways. First, forgetting allows us to adapt to new situations by letting go of outdated and potentially misleading information that can no longer help us maneuver changing environments.
“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 second way forgetting facilitates decision making is by allowing us to generalize past events to new ones. This is your brain prioritizing core information but eliminate specific details, allowing for wider application. When we only remember the gist of an encounter as opposed to every detail, this controlled forgetting of insignificant details creates simple memories which are more effective at predicting new experiences.
Similarly, research shows that episodic memories of things that happen to us are forgotten more quickly than general knowledge that we access on a daily basis, supporting the old adage that if you don’t use it, you lose it.
So when it comes to making good decisions – perhaps especially in the context of the tangled world of human relationships – it sounds like you might be better off with a brain that is working to forget.