Searching For Memory

ACKNOWLEDGMENTS

THE SEEDS OF THIS BOOK were sown in 1975, when I worked as a research assistant for Dr. Herbert Crovitz at a Veterans Administration Hospital in Durham, North Carolina. There I tested braindamaged patients who were utterly incapable of remembering new information for more than a few seconds. One man conversed easily when we first met and seemed more or less like anyone else. But when I left the room and returned several minutes later, he had totally forgotten we had ever met. Startled and intrigued by such dramatic disorders, I developed a deep and enduring interest in memory that I have pursued for the past two decades.

I have had much help along the way. Herb Crovitz ignited my interest in memory, and Endel Tulving nurtured it during my years in graduate school and ever since. I have been fortunate to work closely with many fine psychologists and neuroscientists during the past two decades. For their contributions to research described in this book, I am indebted to Marilyn Albert, Nat Alpert, Barbara Church, Lynn Cooper, Tim Curran, Elizabeth Glisky, Peter Graf, Joanne Harbluk, John Kihlstrom, Bill Milberg, Morris Moscovitch, Mary Jo Nissen, Michael Polster, Scott Rauch, Eric Reiman, Cary Savage, Endel Tulving, Anne Uecker, Mieke Verfaellie, and Paul Wang—to name only some of my collaborators. I have received pointers and advice concerning phenomena and issues addressed in these pages from numerous colleagues, including Steve Ceci, Mary Harvey, Jake Jabobs, Eric Kandel, Michelle Leichtman, Elizabeth Loftus, James McGaugh, Richard McNally, Roddy Roediger, and Larry Squire. The members of the memory working group in Harvard’s Mind/Brain/Behavior initiative—Emory Brown, Joseph Coyle, Jordan Fieldman, Gerald Fischbach, Jerry Green, Jerome Kagan, Elaine Scarry, and Lawrence Sullivan—have helped me to think through issues addressed in this book during numerous stimulating discussions. I am especially grateful to colleagues and students who provided perceptive comments on various drafts of the entire manuscript: Laird Cermak, Tim Curran, Stephen Kosslyn, Wilma Koutstaal, Ken Norman, Kevin Ochsner, and Robin Rosenberg. For tracking down references all over the Boston area, I thank Gayle Bessenoff and Lissa Galluccio, and for keeping track of the ever-increasing bibliography, I am grateful to Mara Gross and Kim Nelson. Maura Wogan provided helpful advice concerning pragmatic aspects of this endeavor. My wife, Susan McGlynn, not only provided useful feedback on the evolving manuscript, but also put up with too many occasions when my need to write just one more page kept me from family duties. Her love and support throughout this project have helped me more than she can imagine.

I am fortunate that my research has been supported by various public and private agencies, and I am deeply grateful to all of them: Air Force Office for Scientific Research, Connaught Foundation, Charles A. Dana Foundation, McDonnell-Pew Program in Cognitive Neuro-science, National Institute on Aging, National Institute of Neurological Diseases and Stroke, National Institute of Mental Health, and Natural Sciences and Engineering Research Council of Canada. Much of that research has involved people with shattered memories. I am especially thankful for all the time and effort expended by patients and their families during participation in our research projects. To protect their privacy, I have used fictitious names or initials for patients who took part in my studies, and have also changed some background information about them.

Although this book is primarily about the scientific study of memory, I have also drawn on the inspiration of artists. In the course of acquiring a collection of artworks in which memory is a central theme, I have been unfailingly impressed by the dedication and humanity that so many artists bring to their work. I am grateful that they have allowed me to share their creations and tell their stories. All artworks reproduced in this book, except for Magritte’s “The Menaced Assassin,” are from my personal collection.

At Basic Books, I have been fortunate to work with a number of skilled professionals. Jo Ann Miller, now with John Wiley and Sons, provided wise counsel and insightful editorial guidance from the inception of this book until near its end. Susan Rabiner stepped in during the latter phases of the project with grace, enthusiasm, and intelligence, helping to improve the final product significantly. Linda Carbone kept finding ways to help me communicate more clearly and succinctly, even when this project intruded on her early days of motherhood; I greatly appreciate her commitment.

My greatest debt is to my family, Susan, Hannah, and Emily, the source of my most vital memories.

INTRODUCTION

Memory’s Fragile Power

IN GABRIEL GARCÍA MÁRQUEZ’S epic novel One Hundred Years of Solitude, a strange plague invades the small village of Macondo, causing the inhabitants to lose aspects of their memories. The symptoms develop in stages. Each villager loses the ability to call up childhood recollections, then the names and functions of objects, later the identity of other people, and finally “even the awareness of his own being.”

A silversmith, frightened when he cannot come up with the word anvil to describe the tool he has always worked with, frantically goes about placing written labels on every item in his home. Inspired by the method’s seeming success, José Arcadio BuendÍa attempts to label everything in the village:

Distressed at the thought of a life of endless labeling, BuendÍa makes a heroic last attempt to save the memory of the villagers: he tries to develop a memory machine that will store written entries of all the experiences and knowledge accumulated in each person’s life. After devising fourteen thousand entries for the machine, mercifully, Buendía is freed from this nightmare by a stranger who cures him of the plague. With a cure comes the full restoration of his memory. Only then does he recognize the stranger as an old and dear friend.

The novel dramatizes a world without memory: a world in which even close friends and family members seem like strangers; a world in which symbolic forms of communication are useless, and most of the tasks on which society depends cannot be performed; and, perhaps most tellingly, a world in which our sense of personal identity and self-awareness is stripped away. The narrator in Saul Bellow’s The Bellarosa Connection, who runs a memory-improvement institute, sums it up for his clients: “Memory is life.”²

Yet, except for those annoying moments when memory fails or when someone we know is afflicted with memory loss, most of us are barely aware that just about everything we do or say depends on the smooth and efficient operation of our memory systems. Stop and think for a moment about what is involved in just one simple task: arranging to meet a friend at a restaurant. For starters, you must be able to bring to mind your friend’s name and phone number as well as the information needed to execute the call. Then you must use your memory of voices to identify the person who answers the phone as your friend. Throughout, to hold up your end of the conversation and to understand what is being said to you, you must constantly access an internal dictionary of words, sounds, meanings, and syntax. At some point you must search through memories of visits to restaurants, or recommendations of new ones, in order to determine which restaurant would be a good choice. You must be able to call up details of your friend’s personality, special interests, and anything else that will contribute to harmony and avoid provocation or confrontation. Later, you must call upon knowledge and skills that remind you how to get physically from here to there. Finally, you must be fully aware of what else is going on in your life so that you do not schedule the meeting for a time when you already have something planned.

We perform these feats of memory naturally, even though the tasks require the virtually perfect operation of memory-retrieval systems with processes so complex that even the most advanced computer would not be able to carry out the assignment as easily and effectively as we do. Now consider that we rely on these systems to perform similar feats countless times each and every day of our lives.

Like other biologically based capabilities, memory is generally well adapted to such everyday demands of life, because it has evolved over countless generations in response to the pressures of natural selection. A foraging animal who can remember locations where food has been found has an important survival advantage over a competitor with less accurate recall; an inhabitant of the jungle who can recognize quickly the signs of a dangerous predator stands a better chance of escape than a competitor with slower or foggier recognition processes. Indeed, we can guess that many features of memory survived the rigors of evolution precisely because they helped animals and people survive and reproduce; any memory system that consistently produced serious distortions would not be likely to survive many generations.³ While far from perfect at meeting all human needs, our own memory systems do a remarkably good job of handling the staggering variety of demands we place upon them.

Yet memory’s reputation has been tarnished lately. We hear disturbing reports of false traumatic memories in therapy patients. We read strange stories of people who vividly recall alien abductions. And we learn that scientists have come up with simple ways to induce some of us to remember clearly events that never happened!

Does this suggest that as accurate as memory is in most situations, it is less consistently reliable than we once believed it to be? Or that its reliability is conditional, highly accurate in some situations or under some conditions—perhaps when our well-being or even our survival is at stake—but less so in other circumstances? Or that it is highly reliable in allowing us to recall a general sketch of moments from the past, but much less reliable in its recall of specific detail?

We’ve all had firsthand experience with memory’s imperfections. I once asked a colleague how long it had been since he shaved his beard. He replied in bewilderment that he had always been cleanshaven. Each of us had perfect confidence in his own memory, yet the two were in conflict. Likewise, all of us have had the uncomfortable experience of being unable to pull up a word or a name we once knew well, failing to recognize a face that ought to seem familiar, or drawing a blank when a friend reminds us of something we supposedly did together. Why is it, we may ask, that trying to remember the past is sometimes like trying to capture a darting phantom? Is this evidence of the imperfection of evolution? Or, rather, of the side effects of its advantages? Imagine having immediate access to everything you ever knew or experienced. Is protection from the chaos that would result the price we pay for the occasional inability to retrieve information we need or want at the moment?

Researchers studying memory have begun to grapple in earnest with these and other equally intriguing questions about how we remember the past. For example, to study emotion, researchers often ask their subjects to call up the saddest or happiest moment of their lives. Remarkably, it has been observed that the act of remembering sad episodes can bring people to tears within moments, and remembering happy incidents can induce an almost immediate sense of elation. Why does memory have such power in our lives?⁴

To begin to answer the questions I’ve raised, we must first try to understand what memory is. Twenty years ago, when I first entered the field of memory research, it was fashionable for cognitive psychologists to compare memories to computer files that are placed in storage and pulled out when needed. Back then, nobody thought that the study of memory should include the subjective experience of remembering. We now believe with some degree of certainty that our memories are not just bits of data that we coldly store and retrieve, computerlike. Artists and writers, of course, have long been aware of the importance of subjective experience in memory, and I am often struck by their prescient comments about what memory has meant to them in their creative work.

For instance, in Matthew Stadler’s novel Landscape: Memory, the story’s protagonist, Maxwell Kosegarten, starts to paint a landscape he saw several years earlier. The painting develops slowly, over time, as Maxwell retrieves and explores his memory again and again. As he paints, he confronts the discrepancy between the view of memory as a static reproduction and what his own experience is telling him. He writes:

Philosophers and writers have sought to penetrate memory’s mysteries for centuries, and scientists have struggled with remembering and forgetting for more than one hundred years. For much of this time, progress has been slow, but the study of memory has undergone dramatic changes during the past couple of decades, some even revolutionary. Most important, we have now come to believe that memory is not a single or unitary faculty of the mind, as was long assumed. Instead, it is composed of a variety of distinct and dissociable processes and systems. Each system depends on a particular constellation of networks in the brain that involve different neural structures, each of which plays a highly specialized role within the system. New breakthroughs in brain imaging allow us to see, for the first time, how these specific parts of the brain contribute to different memory processes.

In this book I identify and discuss different types of memory that enable us to hold information for brief periods of time, to learn skills and acquire habits, to recognize everyday objects, to retain conceptual information, and to recollect specific events. Acting in concert, these memory systems allow us to accomplish the tasks of our day-to-day lives while also supplying our intellect and emotions with ideas and feelings from the past that allow us to act with purpose and live rich emotional lives. But memory involves more than just our remembrance of things past. As we have come to learn that memory is not one single thing, we’ve opened up a whole new world of implicit, nonconscious memory that underlies our abilities to carry out effortlessly such tasks as riding a bicycle or playing a piano, without having to direct each movement consciously every time we attempt the task. Many of us think of this type of memory as being stored in our fingers, but new research is uncovering that specific brain systems are involved in the nonconscious effects of the past on the present.