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The Ways Forgetting Makes You Smarter

Wiping away dated or irrelevant facts clears the way for new learning.

Inside the folds of your cerebrum some 86 billion nerve cells communicate through trillions of synapses to accomplish perhaps the smartest thing a creature can do: forget.

The human brain is the mammalian epicenter of behavior, homeostasis, personality, imagination, and intelligence. It can conceive of numbers and count, learns recipes and cook, and keep domestic and foreign biologies in check [1]. That’s a lot to remember.

Estimates of human memory capacity vary, but it’s safe to say that the 19 million volumes held in the Library of Congress, or 300 years of continuous TV viewing, would not begin to fill our brains. Gargantuan amounts of information are input, encoded, and later retrieved via a combination of chemical and electrical messaging that herds those synaptic assemblies into neural networks. The formation and maintenance of these connections is what creates memory. Until quite recently, forgetting was considered a failure of this process.

But now new research suggests that forgetting is a brain safety mechanism that protects us from information overload [2]. Rather than a failure of memory, evidence shows that forgetting involves a distinct neural mechanism of its own. The deliberate weakening of synapses that encode recollections allow their overwriting by new memories. While it makes old memories harder to access, it gives us the most recent and relevant information with which to make decisions.

In other words, forgetting where you put your keys is part of a critical brain process that makes you smarter. As you try to make informed decisions and navigate the world, your brain is constantly throwing up conflicting recollections. Yesterday morning you put your keys on the counter, two nights ago you hung them by the door, while before that you left them in your raincoat. Filtering through many possible scenarios isn’t helpful when you last put your keys on the kitchen table. The aim of intelligence is to make favorable decisions quickly. And doing that requires synaptic pruning.

Your mind is faster that any supercomputer yet seen. What separates us most from fast computers is not that we can remember who won the World Series in 1999 or who wrote the Nancy Drew novels, but the ability to imagine a tool to do that for us. The device on which you are reading this column is a tool of our own creation. It serves to store the weight of facts that could easily weigh us down. While generations of smart scientists were building and coding the device at your fingertips, the coding language and math behind it that they remembered while building it was only accessible because of the other things they forgot.

The New York Yankees took home the trophy in 1999, and Carolyn Keene is the name under which generations of ghostwriters penned the Nancy Drew stories. At the time such information seemed relevant. Now it’s more relevant to remember what you learned from those books or that game, and apply the lessons to new situations. Forgetting past details clears mental attention for the current baseball season, or for the books you’re reading now. And it allows you to remember where your keys are.

Of course, when you are late and keyless this trick of mental housekeeping is frustrating nonetheless. How do you remember details when you need to?

Encoding is the process whereby we commit facts to memory. It is relatively simple: The more often you remember something, the easier is it to recall in the future when you need to. It helps both procedural memory (what we know) and declarative memory (how to do something). That is why social experts recommend repeating someone’s name when you’re introduced – “It’s nice to meet you, Richard.” The repetition helps push Richard’s name into long–term memory. Likewise with practice, the more times you practice a language or hitting a tennis ball, the better you become at that skill.

What else helps? No surprise here: a balanced and moderate diet, exercise, and adequate sleep. A sensible diet gives your brain fuel to function at its best. Exercise releases hormones that energize both body and brain. And sleep perhaps affords the brain the downtime it needs to process and consolidate what you have learned, thus making it easier to recall later.

When all else fails, please remember that forgetting your keys is all part of the natural process of becoming smarter. Learn more about memory from this great TedEd video:

Comment to Dr. Cytowic at, or to receive his low-frequency newsletter and a copy of Digital Distractions: Your Brain on Screens. Follow him on Twitter @Cytowic , check him out at LinkedIn, or at his website,

See his TED-Ed lessons, “What Color is Tuesday?” and "What Percentage of your brain do you use?"



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