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What’s it like to have all your memories erased? Well, not all your memories, because if that happened, you’d simply be like a newborn infant, and you’d have to relearn everything. The more interesting scenario is to lose only certain memories — the memories that most people think of as “true” memories: episodic memory.
Memories can be divided into three rough categories: episodic, semantic, and procedural (there are actually many more categories). Procedural memories are the memories of how to do things: driving a car, walking, sewing, and so on. Semantic memories are bits of factual knowledge: names, places, meanings. Episodic memories consist of the explicit recollection of specific events: prom night, my trip to Monument Valley, and so on.
A few nights ago, Greta and I watched the movie Unknown White Male, which purports to be a true case history of a 33-year-old man, Doug Bruce, who suddenly and inexplicably lost his entire episodic memory and much of his semantic memory. In fact, the movie demonstrates the inadequacy of such categories — what, for example, is the memory of the concept “ocean”? In one sense, it’s purely semantic: an ocean is a large body of salt water. But when Bruce visits the ocean for the first time following his amnesia, he is overwhelmed with a vast array of new sensations, from the sound and power of the surf, to the water filtering the soft sand through his feet. This particular ocean visit could become an episodic memory, but isn’t there a semantic aspect to the power of the surf? Bruce can’t remember whether or not he can swim, but when he dives into the water, he quickly realizes he can stroke effortlessly through the waves. Is all knowledge of swimming procedural, or are there finer points of such knowledge, such as “keep your elbows up” better characterized as semantic?
In some ways, these distinctions are irrelevant, but in others they are the key to understanding Bruce’s condition. What does it mean to “lose your memory”? Why can he still drive a car, retain his aptitude and interest in photography, but lose all knowledge or interest in cricket, a sport of which he had been an avid fan his entire life?
Typically amnesia is the result of physical trauma and is a rare, temporary condition; individuals such as Doug Bruce with no evidence of injury are exceedingly rare. Indeed, amnesia is often used as a plot device for film or books — it’s an intriguing concept, but one rarely seen in real life. Even more unusual is for the condition to continue as long as it has in Bruce’s case — over two years. It seems that a more plausible explanation of his case is that he’s faking it.
Yet if Bruce (with, or without the complicity of the filmmakers) is perpetrating a fraud on us, it’s an effective one. Renowned neuroscientist Dan Schacter is convinced, and lends his expertise to the film in a series of interviews explaining key concepts of memory and amnesia. His doctors, his friends, his family all genuinely believe Bruce has lost his memory. Indeed, if he is merely reconstructing the impression of being amnesic, he’s doing it so effectively that there’s little point in speculating as to whether he’s truly experiencing the astonishing phenomena he reports in the film.
When it snows for the first outside Bruce’s New York apartment, he videotapes it with the wonderment of a child. He rushes down to the street and picks up a handful as if he’d never experience such a substance, crushing it in his hand, amazed at its frigid malleability. When he meets friends and family for the first time after the event, it’s as if he’s meeting them for the first time. “You look just like your picture,” he tells a friend of 20 years.
I do have one quibble with the science depicted in the film. The doctors tell Bruce there is a 95 percent chance he’ll eventually get his memory back, and the filmmaker reports this back to the audience as if it’s established scientific fact. In reality, there’s no way they can indicate his odds with such precision: 95 percent simply reflects the concept of statistical significance. Researchers in this field will say a result is significant if they are replicable at least 95 percent of the time. His chances are likely better than 95 percent, but there’s no way to give his chances with any better precision.
Despite these limitations, the film is a fascinating exploration of the experience of having retrograde amnesia. Even more fascinating is the fact that Bruce began filming himself just a few days after losing his memory, so we have a nearly complete record of a two-year period where we watch Bruce try to rebuild his life. It offers a profound exploration of the impact of amnesia, on both the victim and his friends and family. It leaves the viewer with nearly as many questions as answers about what amnesia must be like, but I view that as a good thing: we should be thinking about such things, if only to be thankful that amnesia is so rare.
March 23, 2006
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