Have I Been Here Before?
The science behind memory and déjà vu
How does your brain tell the difference between somewhere you have been and somewhere you haven’t? As we wander around our world, we encounter many familiar places along familiar routes — houses and shops, bars and cafes. If we wander off somewhere new, we instinctively, instantly, know it is new. And we form new memories: These new places become familiar.
By clever tricks of wiring in the hippocampus, our brains store this new place as a new memory set apart from all previous memories. When these tricks go wrong, they give you the creeping sensation — the déjà vu — that, impossibly, you’ve been here before.
When you walk into work, how do you know you’re at work? Or at home, or the shops, or your office? That constant feeling of familiarity is a really odd, metacognitive sensation. Without thinking, you know that you know where you are every minute of every day. Imagine if we couldn’t feel familiarity. Everywhere, everywhen, would be a new experience. It would be overwhelming, disorienting, every minute of every day like being a newborn baby who happens to walk, talk, and wipe its own bum.
Some seriously heavyweight calculations are happening in your brain to make such an everyday sensation. Deciding if someplace is familiar or not needs a comparison between the…
