Doubleday
Review by Walter Cummins
It occurred to me that one approach to reviewing of Ranganath’s explanation of human memory would be to test my own memory as I recall what stuck with me from the vast amount of information he provides. Why have I held onto certain facts and overlooked others? Is what matters to me different from what matters to others? If so, what does that say about who I am?
In the book’s coda Ranganath admits for all that he does know about memory there is much he does not: “Why do we remember? Almost thirty years after pasting those sticky electrodes on the head of my first experimental subject, I still don’t have a simple answer.” Yet he and his fellow researchers have accumulated quite a bit that addresses the complexity.
But which of the partial answers he discusses taught me something I considered significant enough to want to retain? One certainly is the division between episodic and semantic memory, a distinction first made by Endel Tulving at the University of Toronto in 1972:
He coined the term episodic memory to describe the kind of remembering that allows us to call back, and even reexperience, events from the past. Tulving proposed that episodic memory can be differentiated from semantic memory, our ability to recall facts or knowledge about the world, regardless of when and where that information was learned. Tulving’s key insight was that, to remember an event (episodic memory), we need to mentally return to a specific place and time; but to have knowledge (semantic memory), we need to be able to use what we previously learned across a range of contexts.
Semantic memories are what I or any other reader may take away from this book. Ranganath in a chapter on studying for exams suggests strategies for improving this type of memory by, instead of cramming and rereading, testing and correcting ourselves—error-driven learning—as well as getting a good night’s sleep and letting our unconscious brains process the knowledge more effectively: “… when memories are reactivated during a test, error-driven learning helps to strengthen those specific memories, but when memories are reactivated during sleep, error-driven learning helps the brain to use threads of disparate experiences to weave a tapestry of knowledge.” Digest a few chapters and take a nap.
The episodic, however, hold more significance in shaping our identities: “Far more than simple recall, episodic memory connects us to those transient moments from the past that make us who we are in the present.” Such memories and their possible enhancement or distortion appears to be Ranganath’s primary concern.
“Memory is much, much more than an archive of the past,” he writes, “it is the prism through which we see ourselves, others, and the world. It’s the connective tissue underlying what we say, think, and do.” Rather than seeking a photographic goal, memory shouldn’t be locked in, but rather be adaptive to help us cope with the now and prepare for what is to come:
Forgetting isn’t a failure of memory; it’s a consequence of processes that allow our brains to prioritize information that helps us navigate and make sense of the world. We can play an active role in managing forgetting by making mindful choices in the present in order to curate a rich set of memories to take with us into the future.
A central question for Ranganath is why of the plethora of potential memories that bombard us each day only a fraction stick. Our brains prioritize and are constantly being reshaped as memories contest for space in our everchanging neurons. Because I know so little about brain functioning, all of this semantic information was new to me and somehow reassuring as I learned that scientists have some comprehension of the roles specific areas of the human brain play in the retention, loss, and shaping of our memories. For example, “Likewise, several regions all over the human brain have relatively specialized functions, and the job of the prefrontal cortex is to serve as a central executive, coordinating activity across these networks in the service of a mutual aim.”
When we experience a new memory, its various aspects are stored in cell assemblies that are separate and unconnected areas of the brain. But the hippocampus, which has connections to many of these areas, contains links that bring them to life during the creative act of remembering:
The human brain is not a memorization machine; it’s a thinking machine. We organize our experiences in ways that allow us to make sense of the world we live in. To handle the complexities of the world, without falling prey to interference, we can exploit one of the brain’s most powerful tools for organizing information: the schema. A schema is a kind of mental framework that allows our minds to process, organize, and interpret a great deal of information with minimal effort.
Studies have shown that the framework of schemas reveal close similarities in brain activity between the processes of imagination and memory. Ranganath cites the English psychologist Sir Frederic Bartlett, who stated that our recollections are only approximations: “Remembering is not the re-excitation of innumerable fixed, lifeless and fragmentary traces. It is an imaginative reconstruction.”
Ranganath considers memories as analogous to paintings rather than photographs, with details that are embellishments and interpretations from the artist’s perspective: “Memories, we will see, are neither false nor true—they are constructed in the moment, reflecting both fragments of what actually transpired in the past and the biases, motivations, and cues that we have around us in the present.” Therefore, memory is a combination of what happened and interpretations of what happened. Memories share much with the products of creative arts.
Because memory involves so many similarities with the process of imagination, studies have shown that “we are especially vulnerable to misinformation at the moment of remembering.” Fortunately, according to Ranganath, we have some control over the accuracy of our memories: “… memory updating rarely leads people to form completely new memories for extreme or traumatic events. And we all can use this emerging understanding to avoid the negative consequences of memory updating and instead harness its power to improve our lives.”
In short, the nature of our memories results from a complexity of mental processes and physical influences. Memory makes us who we are and allows us to cope with the world we live in, the better shape of our memories—the richness of our set—the better our functioning. This semantic memory makes me more conscious of what’s involved when I revisit episodic memories and why I am doing it. Who I am shapes the creative processes of my unique remembering.
