How Memory Works and Why It Fails

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The science behind memory formation and forgetting

I wish I could prescribe Lisa Genova’s new book, Remember: The Science of Memory and the Art of Forgetting, to everyone who comes into my clinic asking about why that hard-to-get name sits at the tip of their tongue or why they walk into a room and immediately forget the reason they entered it in the first place. Each one of these patients has one question on their mind: Is this dementia? If you want to understand how memories are formed, appreciate the difference between normal age-related memory lapses and Alzheimer’s, or learn how to improve your memory and reduce the risk of developing dementia, then this is the book for you.

Lisa Genova, a neuroscientist and author of such critically acclaimed books as Still Alice, brings her expertise in brain science and her powers as a storyteller to the cognitive domain of memory. Without feeling like a self-help book, the book offers evidence-based how-to’s for boosting recall. One of its key aims is normalizing forgetfulness. Providing outlier examples such as the case of Yo-Yo Ma, the acclaimed cellist who can commit to “muscle memory” thousands of notes yet forgot his prized cello in the trunk of a New York cab, and that of a regular 65-year-old man who decided to memorize over 100,000 digits of pi but forgot his wife’s birthday, Genova explains why lapses like these aren’t so very different from our own misplaced glasses or missed appointments. Why? She explains that “we often forget not because it’s efficient for our brains to do so but because we haven’t supplied our brains with the kinds of input needed to support memory creation and retrieval.” She explicates these faulty inputs, such as our failing to deploy enough attention in the first place or leaving a memory flimsy by not reflecting on its meaning or salience to us, and she gives techniques on how to improve them. One success of the book is that it grounds the discussion in physical terms. Every step of the process of memory formation and functioning — encoding, consolidation, storage, and retrieval — is articulated in jargonless prose. Genova explains how these steps are grounded in physical structures in the brain, identifying the neural circuits that we currently believe undergird memory and its important but often maligned foil, forgetting.

The art and science of forgetting is another important theme. Simply put, it can be a blessing to forget. Through extreme examples, such as the intrusive memories that accompany post-traumatic stress disorder and the mental clutter of mnemonist savants, Genova makes the connection to commonly shared experiences like punching in your expired password automatically even though you changed it two weeks ago. She argues that forgetfulness plays an important role in keeping the rest of our mental processes unburdened by the weight of useless recollections, and even hints at ways to improve our forgetting of events we’d rather not remember.

Remembering and forgetting are not simply cast as a binary in Genova’s account; she also explores the quality and veracity of memory. There is a fascinating investigation into so-called “flashbulb memories” like the ones people have of JFK’s assassination or 9/11. Such memories of “stunningly unexpected, personally important, and emotionally charged experiences . . . that feel resistant to fading and can be readily recalled years later” turn out not to be impervious to manipulation. When recalling an experience, we reactivate pathways in the brain that facilitated the making of the memory in the first place. In a physical sense (as far as some parts of our brains are concerned), we are re-experiencing parts of the event. But we don’t remember all the details in exactly the same way. Sometimes we miss a few details in the retelling, overemphasize other details, or are introduced to new information, and so, when the memory reconsolidates, a new version replaces the old.

Genova cites the work of Ulric Neisser, who asked his college psychology students, on the day that the Challenger exploded, to answer experiential questions about what they were doing and whom they were with when it happened. He found that two and a half years later, when asked to perform the same exercise, no students gave the same answers as they had initially, and 25 percent of students were 100 percent inconsistent in their answers. A year later, when shown both sets of answers in their own handwriting, a subset of students dismissed outright their earliest recollection and stuck to their more recent stories.

Memories, even emotionally powerful ones, are malleable in the fullness of time. But recall can also be manipulated by the prompt. Genova relays one study in which people watched a video snippet of two cars about to collide. In questions asked about the cars’ approximate speed, substitution of verbs like smashed for ones like bumped influenced observers’ recollections (and therefore their estimations) of the cars’ speed. The experiment also illustrated the power of memory insertion. Those asked questions containing verbs like smashed were more likely to remember seeing broken glass than those who were asked with verbs like bumped. The video didn’t show broken glass. Their memories of broken glass were false.

After working through how memories are formed and why forgetting happens, the book switches gears to compare how the deterioration of memory and a person’s response to forgetting in clinical dementia differs from natural aging. There’s forgetting your keys and finding them on the sideboard, which makes you recall setting them down to answer an unexpected phone call, as opposed to losing your keys until you get your frozen dinner out of the fridge and find them in the ice box. There’s forgetting how to spell a rarely used word, and then there’s forgetting how to draw a letter of the alphabet. Folded into Genova’s explication of the mechanics of memory are useful tips readers can incorporate into their everyday lives — and for those who forgot them as they read, there’s an appendix in the back of the book. Genova also debunks commonly repeated pharmacologic fables — such as the notion that eating chocolate or drinking wine will salvage your memory (it won’t).

For those familiar with the greater Boston area, the book is an especial treat, as many of her examples include familiar landmarks. In writing about the nth time she traveled from Kendall Square to a vacation spot on Cape Cod, Genova relates that she realized she couldn’t remember driving over a particular bridge, and yet she knew she must have. Does this mean she’s losing her memory? No, in fact she never made a memory of it in the first place, because the entryway to memory is not just perception — she certainly saw the bridge on her drive — but attention. The familiar landmarks of overlearned drives just fade into the background, as they are without consequence or interest. We become habituated to them.

The goals of Remember are important, and its message is as wise as it is hopeful. In some ways, it’s a kind of public-service announcement that can capture a reader’s attention, and Genova’s hope to humanize forgetting comes to fruition through her warm, conversational prose. Memory is seen by many as such an enormous building block to our identity that to forget is to self-destruct, but, to quote the author, “If we can embrace the notion that forgetting is a normal part of being human, then Alzheimer’s won’t be such a dramatic fall from grace.”

Michael P. H. Stanley, M.D., is a poet, historian, and neurology resident of the Harvard BWH-MGH Neurology Program.


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