Can’t remember what you bought at the grocery store last week or the password to your old eBay account? Good news — according to science, this means your brain is healthy.
Though many might blame the inability to recall details on aging or over-scheduling, a June study published in neuroscience journal Neuron found that the process of forgetting is not only normal, but actually makes you smarter by separating the wheat from the chaff.
“The real goal of memory is to optimize decision-making,” says University of Toronto’s Blake Richards, a co-author of the study. “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.”
In short, your brain should have better things to do with its bandwidth than recall the capital of South Dakota or who won last year’s Olympic gold medal in curling — having to wade through reams of extraneous information makes it more difficult for the brain to come to a concrete conclusion.
“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.
Richards and co-author Paul Frankland, also from the University of Toronto, studied years of data on memory loss and brain activity in both people and mice. They discovered that the growth of new neurons in the hippocampus, the region of the brain associated with learning and memory, is correlated with forgetting. Because new cell growth also corresponds with youth, the researchers found that this might explain why people often have no memory of events that happened before the age of 4.
This overwriting of old memories with new neuron growth can also help the brain’s ability to generalize previous events to better apply them to current and future situations — lumping together multiple past trips to a vacation destination, say, as opposed to individual details from each year. (You might remember that a certain resort has a fun pool, instead of recalling specific games you played there in 2013 and 2014.)
Richards points out that his study echoes a phenomenon that is often observed in artificial intelligence — when a machine stores too much information, it can hinder its ability to generalize and make intelligent decisions, a problem called “over-fitting.” In a June interview with NPR, Richards mentioned that he hopes a better understanding of how human brains decide what information to keep and what information to forget can eventually lead to better AI technology.
In the meantime, Richards says we should probably stop being so hard on ourselves for lack of total recall.
"We all admire the person who can smash Trivial Pursuit or win at Jeopardy, but the fact is that evolution shaped our memory not to win a trivia game, but to make intelligent decisions," says Richards. "And when you look at what's needed to make intelligent decisions, we would argue that it's healthy to forget some things."