Sherlock Holmes and the infamous brain attic

Illustration: tisserande

Maria Konnikova is the author of Mastermind: How to think Like Sherlock Holmes, out January 2013 from Viking, and a blogger at Scientific American. Visit her website and follow her on Twitter.

One of the most widely held notions about Sherlock Holmes has to do with his supposed ignorance of Copernican theory. "What the deuce is [the solar system] to me?" he exclaims to Watson in A Study in Scarlet. "You say that we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or to my work." And now that he knows that fact? "I shall do my best to forget it," he promises.

It's fun to hone in on that incongruity between the superhuman-seeming detective and a failure to grasp a fact so rudimentary that even a child would know it. And ignorance of the solar system is quite an omission for someone who we might hold up as the model of the scientific method, is it not? Even the BBC series Sherlock can't help but use it as a focal point of one of its episodes.

But two things about that perception bear further mention. First, it isn't, strictly speaking, true. Witness Holmes's repeated references to astronomy in future stories—in "The Musgrave Ritual," he talks about "allowances for personal equation, as the astronomers would have it"; in "The Greek Interpreter," about the "obliquity of the ecliptic"; in "The Bruce-Partington Plans," about "a planet leaving its orbit." Indeed, eventually Holmes does use almost all of the knowledge that he denies having at the earliest stages of his friendship with Dr. Watson. (And in true-to-canon form, Sherlock the BBC series does end on a note of scientific triumph: Holmes does know astronomy after all, and that knowledge saves the day—and the life of a little boy.)

In fact, I would argue that he exaggerates his ignorance precisely to draw our attention to a second—and, I think, much more important—point. His supposed refusal to commit the solar system to memory serves to illustrate an analogy for the human mind that will prove to be central to Holmes's thinking and to our ability to emulate his methodology. As Holmes tells Watson, moments after the Copernican incident, "I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose."

When I first heard the term brain attic, all I could picture in my seven-year-old head was the cover of the black-and-white Shel Silverstein book that sat prominently on my bookshelf, with its half-smiling, lopsided face whose forehead was distended to a wrinkled triangle, complete with roof, chimney, and window with open shutters. Behind the shutters, a tiny face peeking out at the world. Is this what Holmes meant? A small room with sloped sides and a foreign creature with a funny face waiting to pull the cord and turn the light off or on?

As it turns out, I wasn't far from wrong. For Sherlock Holmes, a person's brain attic really is an incredibly concrete, physical space. Maybe it has a chimney. Maybe it doesn't. But whatever it looks like, it is a space in your head, specially fashioned for storing the most disparate of objects. And yes, there is certainly a cord that you can pull to turn the light on or off at will. As Holmes explains to Watson, "A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic."

That comparison, as it turns out, is remarkably accurate. Subsequent research on memory formation, retention, and retrieval has proven itself to be highly amenable to the attic analogy.

The attic can be broken down, roughly speaking, into two components: structure and contents. The attic's structure is how our mind works: how it takes in information. How it processes that information. How it sorts it and stores it for the future. How it may choose to integrate it or not with contents that are already in the attic space. Unlike a physical attic, the structure of the brain attic isn't altogether fixed. It can expand, albeit not indefinitely, or it can contract, depending on how we use it (in other words, our memory and processing can become more or less effective). It can change its mode of retrieval (How do I recover information I've stored?). It can change its storage system (How do I deposit information I've taken in: where will it go? how will it be marked? how will it be inte- grated?). At the end, it will have to remain within certain confines—each attic, once again, is different and subject to its unique constraints—but within those confines, it can take on any number of configurations, depending on how we learn to approach it.

The attic's contents, on the other hand, are those things that we've taken in from the world and that we've experienced in our lives. Our memories. Our past. The base of our knowledge, the information we start with every time we face a challenge. And just like a physical attic's contents can change over time, so too does our mind attic continue to take in and discard items until the very end. As our thought process begins, the furniture of memory combines with the structure of internal habits and external circumstances to determine which item will be retrieved from storage at any given point. Guessing at the contents of a person's attic from his outward appearance becomes one of Sherlock's surest ways of determining who that person is and what he is capable of.

Much of our attic's original intake is outside of our control: just like we must picture a pink elephant to realize one doesn't exist, we can't help but become acquainted—if only for the briefest of moments—with the workings of the solar system should Watson choose to mention them to us. We can, however, learn to master many aspects of our attic's structure, throwing out junk that got in by mistake (as Holmes promises to forget Copernicus at the earliest opportunity), prioritizing those things we want to and pushing back those that we don't, learning how to take the contours of our unique attic into account so that they don't unduly influence us as they otherwise might.

While we may never become quite as adept as the master at divining a man's innermost thoughts from his exterior, in learning to understand the layout and functionality of our own brain attics we take the first step to becoming better at exploiting its features to their maximum potential—in other words, to learning how to optimize our own thought process, so that we start any given decision or action as our best, most aware selves.