Context-dependent memory – Remembering something more easily when you're in the same place or situation where you first learned or experienced it. The hippocampus is involved in creating these links, so the context can later help bring the memory back.
Last week I visited Paris and discovered that I had left a memory there. As the plane landed, I suddenly remembered that I had once bought a book in Paris, years ago, but I couldn’t recall which one. I hadn’t thought about that book in ages, and even though I was sure it existed, I just couldn’t remember what it was.
Two days later, I found myself at Shakespeare and Company, the bookstore where I had bought it. I waited in line with dozens of tourists from around the world before being allowed inside (pretty sure it’s the only bookstore in the world with a line at the entrance). I wandered through the shop, and suddenly came across the exact shelf where I had picked up the book, and then I remembered: it was The Book of Disquiet by Fernando Pessoa. A book I love deeply, and yet had somehow managed to forget it even existed.
It’s such a strange thing, that I had to fly all the way from New York to Paris to unlock a memory inside my own brain, one that probably wouldn’t have been triggered any other way.
But why does this happen?
Neuroscience has long been concerned with one of the brain’s biggest mysteries: where exactly is memory stored? For years, scientists thought the brain worked like a computer, that there must be a specific place where all our memories are kept, from the moment we learned to ride a bike to our first love. But as is often the case in neuroscience, the answer turned out to be more complex. Memory isn’t located in one spot. Instead, it’s distributed across a network in the brain. And to bring a memory back, a specific pattern of brain activity, like turning a key in a lock, has to be triggered. Sometimes we have access to that key, and sometimes we don’t. That’s where context comes in. Without the right context, the key doesn’t turn and the memory stays quiet.
A clear example of context-based memory can also be found in birds. In several studies, researchers showed that certain birds can remember the exact spots where they hid food, even weeks later. But they were able to find it only when specific details in the environment were the same as when they hid it. These findings have been repeated in other studies, showing how strongly memory can be tied to physical place.
So what can we do with this knowledge?
If you want to remember something better, it helps to pay attention to your surroundings. For example, students might benefit from looking around the room while studying, noticing where they are, what they hear, even what they smell. Later, when they return to that same room, those small details might help bring the memory back.
But maybe more than anything, it is worth taking a moment to appreciate how amazing our brains are. They do not just store memories, they hide them in places. Like birds that hide their food, we hide our memories. Spread across cities and countries, we may have memories quietly waiting for us on a street in New York, a bookstore in Paris, or a corner in São Paulo. Ideas and thoughts we forgot, tucked away in physical spaces, just waiting to be found again.
This just reminded me that I left Harry Potter and the Prisoner of Azkaban on my El Al flight in 2004.