You contain a 3D sensory map of your life. It is constructed in real-time and space as you move, as you, the pen tip, extend the map. An adult’s map would look like the busy tangle of way-points in the narrative-line of a child’s drawing. You know, the drawn line that accompanies “Then, they went here and saw a witch! They were so scared they had to go over here to the hospital! ”
Can you imagine the map from above? Superimpose it over a world map or your country map. The places you lived a long time are burned in like an angry scribble, the one-off but memorable trips may be like islands only connected to your mainland with faint travel lines. Mixed in with the streets and parks of your memory, attached to them, are the smells of all these places. That incredible honeysuckle jungle by the elementary school playground? It waits for thee. You contain a 3D map overlaid with a museum of scent and stink.
Here’s the bare bones neurology: “Place cells” lay down connect-the-dots, step by step maps of the real world in your hippocampus. They also bind to local aromas, creating our scent memories of specific locations. If you can remember the smell of your grandparent’s home and think about that place, that is this function at work.
- My grandparent’s house smelled like varnish downstairs where Grandpa made furniture and like grape juice, knackebrod, and unknown Swedish spices upstairs in Grandma’s domain. Opening closets and long-closed boxes, even lying on the bedspreads in that house left strong scent memories with no names.
- To return home we rode the Long Island Railroad, smelling of people’s coats, train engine, newspapers and whiffs of the day outside when the train stopped and inhaled.
- Next, the subway, smelling of the warm wind it carried along, orange drinks, hot dogs, and more coats.
- Home, at last, smelling of drink and smoke and many books but above all, smelling of home.
This is why experiencing a sudden strong scent memory takes you out of the moment. You have been contacted by yourself in another time and place. Some memories come when we call them. Others only emerge as you return to their actual spot. It’s as if we suddenly recognize each other, that place (inside us, on our map) realizes we have returned. The surprise of recognition seems to come from both sides. In these very rare moments, I feel the experience of the child I was for a gleaming second before it vanishes like a dream.
Imagine how much more important this is in the lives of animals whose nose is basically their executive function.
Here’s a simple proof of concept game. Consider these smells and try to remember either the last place you smelled them or the place that automatically comes to mind. This would be so much more powerful with actual scents. I found many didn’t immediately suggest a place but if I kept it in mind for a little, a place came into focus, filling in around the scent.
- Hay, fresh-cut lumber, saltwater docks, cedar, aspirin, leather, play-dough, newly printed book.
- And a few less pleasant: Pulp mill, sickroom, smothering perfume, unclean body odor.
Nancy Kanwisher covers the neurology in depth below. (She has an entire MIT neurology lecture course on YouTube.)