Free Moonwalking With Einstein by Joshua Foer

shot him before he made it into the school. But recent graduates of the academy were more likely to let the man with the bomb stroll right up the steps and into the building. They simply lacked the experience to diagnose the situation and react properly. At least that would be the superficial explanation. But what exactly does experience mean? What exactly did the more senior officers see that the younger recruits didn’t? What were they doing with their eyes, what was going through their minds, how were they processing the situation differently? What were they pulling from their memories? Like the professional chicken sexers, the senior SWAT officers had a skill that was difficult to put into words. Ericsson’s research program can be summarized as an attempt to isolate the thing we call expertise, so that he can dissect it and identify its cognitive basis.
    In order to do that, Ericsson and his colleagues asked the officers to talk aloud about what was going through their minds as the scenario unfolded. What Ericsson expected to learn from these accounts was the same thing he’s found in every other field of expertise that he’s studied: Experts see the world differently. They notice things that nonexperts don’t see. They home in on the information that matters most, and have an almost automatic sense of what to do with it. And most important, experts process the enormous amounts of information flowing through their senses in more sophisticated ways. They can overcome one of the brain’s most fundamental constraints: the magical number seven.

In 1956, a Harvard psychologist named George Miller published what would become a classic paper in the history of memory research. It began with a memorable introduction:
    My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals. This number assumes a variety of disguises, being sometimes a little larger and sometimes a little smaller than usual, but never changing so much as to be unrecognizable. The persistence with which this number plagues me is far more than a random accident. There is, to quote a famous senator, a design behind it, some pattern governing its appearances. Either there really is something unusual about the number or else I am suffering from delusions of persecution.
    In fact, we are all persecuted by the integer Miller was referring to. His paper was titled “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information.” Miller had discovered that our ability to process information and make decisions in the world is limited by a fundamental constraint: We can only think about roughly seven things at a time.
    When a new thought or perception enters our head, it doesn’t immediately get stashed away in long-term memory. Rather, it exists in a temporary limbo, in what’s known as working memory, a collection of brain systems that hold on to whatever is rattling around in our consciousness at the present moment.
    Without looking back and rereading it, try to repeat the first three words of this sentence to yourself.
    Without looking back
    Easy enough.
    Now, without looking back, try to repeat the first three words of the sentence before that. If you find that quite a bit harder, it’s because that sentence has already been dropped by your working memory.
    Our working memories serve a critical role as a filter between our perception of the world and our long-term memory of it. If every sensation or thought was immediately filed away in the enormous database that is our long-term memory, we’d be drowning, like S and Funes, in irrelevant information. Most of the things that pass through our brain don’t need to be remembered any longer than the moment or two we spend perceiving them and, if necessary, reacting to them. In fact, dividing memory between short-term and