In the Palaces of Memory

By George Johnson

Copyright 1991 by George Johnson

"You can never dismantle all these modern mental structures. There are so many of them that they face you like an interminable vast city." -- Saul Bellow, The Bellarosa Connection

Whenever you read a book or have a conversation, the experience causes physical changes in your brain. In a matter of seconds, new circuits are formed, memories that can change forever the way you think about the world. I find that idea so remarkable that for the last three years it has been difficult for me to maintain much of an interest in anything else. How is it that memory leaves its mark so that we are able to carry around the past inside our heads?

It has only been in the last few years that scientists have begun to come up with good theories of how this might happen. By breaking down some of the walls that have traditionally divided their fields, psychologists, biologists, physicists, and philosophers are joining in an attempt to answer some of the great questions of human existence: How do we know what we know? How do we make the mental maps -- the structures of memories -- that serve as our guides to the world?

It's a little frightening to think that every time you walk away from an encounter, your brain has been altered, sometimes permanently. The obvious but disturbing truth is that people can impose these changes against your will. Someone can say something -- an insult, a humiliation -- and you carry it with you as long as you live. The memory is physically lodged inside you like a shard of glass healed inside a wound.

For someone who has taken an absolutist view of the First Amendment, this idea raises problems that are difficult to resolve. Freedom of speech is based on the old dualist notion that mind and body are separate things. Hurting someone with a rock is different from hurting someone with an idea. But is it really? As science continues to make the case that memories cause physical changes, the distinction between mental violence, which is protected by law, and physical violence, which is illegal, is harder to understand. Who hasn't had the experience of seeing something so horrible and ugly that it was burned in the brain forever? I'll never forgive David Lynch for his movie "Eraserhead."

Memory is clearly one of those subjects that can expand to engulf volumes. In an attempt to hold it at bay, I have written this book in three sections. Each is a story of someone -- a biologist, a physicist, and a philosopher -- who is trying to learn how memory works.

As in my last book, Machinery of the Mind I'm writing about science in the making, not science already done. By working so close to the cutting edge, I've been able to watch the contest before the final results are in. Science is too often prettied up in retrospect. Once a theory becomes enshrined as the winner, the competition is quickly forgotten. But it's in the messy, sometimes irrational part of the scientific horserace that one can see a mind at work, confronting the unknown. In most newspaper accounts science comes off looking like butterfly collecting. Facts are captured in a net, chloroformed and pinned with labels on a styrofoam board. Theory building is rarely written about. If the subject is broached at all, the assumption is that the scientific "process" works as we were taught in high school: a scientist makes a hypothesis, then designs an experiment to test it. If the experiment confirms the prediction the hypothesis is supported. If the experiment fails, the hypothesis is overturned.

But science hardly ever works that way. A scientist is no more ready to abandon an attractive idea than an author is to give up a novel-in-progress or a composer a symphony. Faced with an onslaught of conflicting evidence, a scientist will make minor adjustments in his theoretical structure, moving a crossbar here, shoring up a support beam there -- doing everything he can to keep his brain child standing. At its worst, a troubled theory can become so laden with elaborations that it comes to resemble the conspiracy theories I wrote about in my first book, Architects of Fear -- closed, hard-shelled systems of thought that resist any attempt at falsification. But even when the scientific process works as it is supposed to, with reality-testing and competition weeding out the bad ideas, the question of how a theory matches up with some kind of real world is a lot more difficult than many scientists like to admit.

Is a theory invented or discovered? Is science just another philosophy whose tenets include materialism and cause-and-effect? Do quarks and electrons exist in the way that marbles seem to, or are they convenient fictions, mental constructs that help us organize data in a useful way? To some extent that is true. But why then do our televisions work? Could we have a successful physics -- one that resulted in nuclear power reactors and nuclear bombs -- if we used other concepts, carving up the world differently? How much of the laws of science are out in the world and how much are inside our heads?

Somewhere toward the end of this project I realized that it had come full circle. The question of what science is and why it is so successful comes back to memory and the way brains convert experience into knowledge.

In his book, The Memory Palace of Matteo Ricci , Jonathan Spence writes about a 16th century Jesuit who brought to the people of China a wonderful memory system that had been used in the West since the days of ancient Greece. To improve their powers of retention, people would build memory palaces -- huge imaginary buildings they kept inside their heads. After years of practice, the images would become so vivid that a person could close his eyes and picture his palace as though it were real. Eventually these mental edifices would become impossible to erase.

If an orator wanted to memorize a speech or a tax collector wanted to remember a list of names, he would mentally place each item inside a room in his own personal memory palace. When he wanted to recall the information, he would enter the front door and wander from room to room, retrieving the memories. The palace was a structure for arranging knowledge.

"To everything that we wish to remember, wrote Ricci, we should give an image; and to every one of these images we should assign a position where it can repose peacefully until we are ready to claim it by an act of memory."

The art of building memory palaces has become a historical curiosity. But in a way, we are unconsciously building structures like this all the time. What Ricci taught as a deliberate mnemonic device comes close to describing what the brain does automatically. As we move through the world, experience is converted into memories. Neuron by neuron we snap together mental structures, constantly evolving palaces of memory that we carry with us until we die.

Unlike Ricci's palaces, ours are invisible to introspection, but slowly scientists and philosophers are deciphering the blueprints of these worlds inside our heads.

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