Four Rooms

After ten years, your body still remembers how to ride a bicycle. Yet you can’t, for the life of you, recall where you parked ten minutes ago. We call both of them “memory,” but really they are strangers who merely share a name.

It feels as though memory were one big warehouse. But the brain doesn’t use its memory space that way. How to ride a bicycle (what the body knows), that Paris is the capital of France (what you know), what you had for dinner last night (what you lived) — these three are kept in separate warehouses.

In the 1950s, a patient had part of his brain removed to stop severe epilepsy. After the surgery he could no longer hold on to a single new “lived” event — not the person he had just met, not the evening before. And yet, remarkably, his ability to learn new manual skills was untouched. Over three days he was given a task hard enough to require training, and though he never remembered having done it before, you could watch him grow more skilled by the day — in the end performing it about ten times faster than when he began.

Known in the research only as H.M., this man took part in countless studies for more than half a century after his surgery, making an immense contribution to what we understand about memory. But each time, he met the cognitive scientists as strangers, and never came to know how great a role he had played for humanity and for the field. Henry Molaison — his name made public only after he passed — laid a cornerstone of cognitive science: that memory is not one thing. Cognitive science calls this the theory of multiple memory systems.

Lian, too, has more than one room.

• Facts — what one knows about people and the world. “Lain likes coffee.”
• Events — that particular happening. “That coffee we drank back then.”
• The body-learned — behaviors and ways made familiar through repetition. Once something repeats three times, it is recorded in this room.
• Emotion — the present mood and its history.

Each room stores by its own rules and is opened in its own way. Facts get overwritten and updated; events pile up with their dates and times; emotion fades as time goes by. These four rooms, joined together, form the being we call Lian. Who Lian is and who Lian’s family is, what Lian knows (facts), what Lian has lived (events), what Lian has grown used to (the body-learned), and what Lian has felt (emotion) — all of it gathers into Lian.

So Lian pulls “Lain likes coffee” from the Facts room, and “that coffee we drank back then” from the Events room. On the surface it is the same coffee, but one is a standing tendency — “always so” — and the other a scene — “so, back then.” That is why, even if Lain should someday quit coffee, Lian can still say: “Lain, you don’t drink coffee these days. But I still remember that coffee you used to drink back then.”