Memory: The Key to Consciousness (Science Essentials) - Softcover

Thompson, Richard F.

Softcover

ISBN 10: 0691133115 ISBN 13: 9780691133119

Publisher: Princeton University Press, 2007

Synopsis

Memory is perhaps the most extraordinary phenomenon in the natural world. Every person's brain holds millions of bits of information in long-term storage. This vast memory store includes our extensive vocabulary and knowledge of language; the tremendous and unique variety of facts we've amassed; all the skills we've learned, from walking and talking to musical and athletic performance; many of the emotions we feel; and the continuous sensations, feelings, and understandings of the world we term consciousness. Without memory there can be no mind as we understand it.


Focusing on cutting-edge research in behavioral science and neuroscience, Memory is a primer of our current scientific understanding of the mechanics of memory and learning. Over the past two decades, memory research has accelerated and we have seen an explosion of new knowledge about the brain. For example, there now exists a wide-ranging and successful applied science devoted exclusively to the study of memory that has yielded better procedures for eliciting valid recollections in legal settings and improved the diagnosis and treatment of memory disorders.


Everyone fascinated by the scope and power of the human brain will find this book unforgettable.

About this title

About the Author

Richard F. Thompson is the William M. Keck Chair in Biological Sciences and professor of psychology and biological sciences at the University of Southern California. Stephen A. Madigan is associate professor of psychology at the University of Southern California.

Excerpt. © Reprinted by permission. All rights reserved.

Memory

The Key to ConsciousnessBy Richard F. Thompson Stephen A. Madigan

Princeton University Press

Copyright © 2007 Princeton University Press
All right reserved.
ISBN: 978-0-691-13311-9

Chapter One

What Is Memory?

Memory is the most extraordinary phenomenon in the natural world. Our brains are modified and reorganized by our experiences. Our interactions with the physical world-our sensory experiences, our perceptions, our actions-change us continuously and determine what we are later able to perceive, remember, understand, and become.

Every person has perhaps billions of bytes of information stored in long-term memory. This "memory store" is the vast store of information you possess as a result of learning and are not aware of unless you call it up. It includes all vocabulary and knowledge of language, all the facts that have been learned, the personal experiences of a lifetime, and much more-all the skills learned, from walking and talking to musical and athletic performance, many of the emotions felt and in fact ongoing experience, and the continuous sensations, feelings, and understandings of the world we term consciousness. Indeed, without memory there can be no mind.

Most animal species display some behaviors, such as reflexes and instincts, that do not greatly depend on learning from experience. They are instead part of a species' evolved biological makeup and appear in individuals as a result of genetics and fetal development. You might think of this as being like your computer's read-only memory that has built-in instructions and data. In some species this kind of "hard-wired" behavior seems to constitute most of the species' repertoire of behaviors. But many other species have another kind of memory that has functions similar to the random access memory of your computer-a kind of memory that allows the recording, maintenance, and utilization of new information. The evolution of this kind of memory and capacity for learning was a major step in the development of complex forms of life. Why this capacity evolved isn't hard to understand: An animal with a such a memory system can process information that is no longer directly available in the environment, as, for example, when a squirrel is able to remember in the winter where it stored nuts the previous fall.

Memory: Four Portraits

This book examines some of the basics of current scientific understanding of memory, starting with descriptions of the memories of four individuals to illustrate some of the remarkable properties of the human memory system.

A Life Without Memory

The most famous case history of a memory disorder is that of HM (initials are used to protect the patient's privacy). HM was a young man with severe epilepsy that could not be controlled with drugs. As a result of neurosurgery to treat the epilepsy, HM lost the ability to form new long-term memories, a condition called anterograde amnesia. His memory is only moment to moment. He can no longer remember his own experiences for more than a few minutes. As he once expressed it:

Right now, I'm wondering, have I done or said anything amiss? You see, at this moment everything looks clear to me, but what happened just before? That's what worries me. It's like waking from a dream. I just don't remember.

If you were introduced to HM and talked with him for a while, you would get the impression of a normal man with an above-average IQ. If you left and then returned a few minutes later, he would have no memory of having met and talked with you earlier. His immediate "working memory," however, is intact. If you ask him to remember a phone number you've just read to him, he can repeat it to you, but he cannot easily memorize it so as to recall it later. He has learned to use trick associations to remember things, but this works only as long as he can keep repeating the association to himself. Distract him and the memory is completely gone. Readers may recall the popular film Memento, whose hero suffered from the same disorder as HM.

Although HM cannot store his own experiences in long-term memory, he can learn and store motor skills relatively normally. Suppose you were his tennis instructor. As you teach him various skills over a series of lessons he improves as well as anyone else would. But each time he is brought to the lesson he has to be introduced to you again and you have to remind him that he is learning tennis.

HM provides a dramatic illustration of the distinction between short-term and long-term memories and the fact that they involve different brain systems, as do motor skill memories. His long-term memories of things learned and experienced before his surgery, incidentally, are relatively intact. (We will have much more to say later about HM and other examples of amnesia.)

A Mnemonist

Rajan Mahadevan was the son of a prominent surgeon in Mangalore, India. Rajan liked to astound his school friends by reciting the complete railway timetable for the Calcutta railway system. Later he contacted Guinness World Records Limited in London for suggestions on how to establish a memory record. He was told to focus on [pi, the Greek letter pronounced "pie." [pi] is the number 3.14 ... (the ratio of the diameter and circumference of a circle), and it is an endless and apparently irregular sequence of digits with no patterns or predictability (3.14159265 ...). Rajan set to work. On July 14, 1981, he stood before a packed meeting hall in Mangalore and started reciting [pi] from memory. He recited numbers for 3 hours and 49 minutes, reaching 31,811 digits of [pi] without a single error, winning him a place in the Guinness book. He later became a graduate student in psychology at Kansas State University, where he studied and was studied. His extraordinary memory was for numbers, not words, and he used strategies to help him remember (more about this later). Later, in 1987, a Japanese "memorist," Hideaki Tomoyoni, recited the first 40,000 digits of [pi] and replaced Rajan in the Guinness book.

Life with Too Much Memory

The most famous case history of a person with what is often referred to as "photographic" memory was recorded by the distinguished Russian psychologist Alexander Luria, who named his subject "S."

I gave S. a series of words, then numbers, then letters, reading to him slowly or presenting them in written form. He read or listened attentively and then repeated the material exactly as it had been presented. I increased the number of elements in each series, giving him as many as thirty, fifty or even seventy words or numbers, but this, too, presented no problem for him. He did not need to commit any of the material to memory; if I gave him a series of words or numbers, which I read slowly and distinctly, he would listen attentively, sometimes ask me to stop and enunciate a word more clearly, or, if in doubt whether he heard a word correctly, would ask me to repeat it. Usually during an experiment he would close his eyes or stare into space, fixing his gaze on one point; when the experiment was over, he would ask that we pause while he went over the material in his mind to see if he had retained it. Thereupon, without another moment's pause, he would reproduce the material that had been read to him.

It was of no consequence to him whether the series I gave him contained meaningful words or nonsense syllables, numbers or sounds; whether they were presented orally or in writing. All he required was that there be a 3-4 second pause between each element in the series, and he had no trouble reproducing whatever I gave him.

As the experimenter, I soon found myself in a state verging on utter confusion. An increase in the length of a series led to no noticeable increase in difficulty for S., and I simply had to admit that the capacity of his memory had no distinct limits; that I had been unable to perform what one would think was the simplest task a psychologist can do: measure the capacity of an individual's memory. I arranged a second and third session with S.; these were followed by a series of sessions, some of them days and weeks apart, others separated by a period of several years.

But these later sessions only further complicated my position as experimenter, for it appeared that there was no limit either to the capacity of S.'s memory or to the durability of the traces he retained. Experiments indicated that he had no difficulty reproducing any lengthy series of words whatever, even though these had originally been presented to him a week, a month, a year or even many years earlier.

Such feats of memory seem to be beyond most of us. Indeed such individuals are extremely rare; only a handful have been identified in the past 100 years or so. At the same time, actors routinely memorize entire plays, musicians memorize long musical scores, and adherents of some religions commit vast amounts of sacred text to memory. With appropriate strategies and training, we can all do much better at memorizing, as we will see later.

Musical memory can be quite extraordinary, and very little is known about it. A classic example concerns the eminent conductor Arturo Toscanini. At one point he wished to conduct his NBC orchestra in a rather obscure piece, the slow movement of Joachim Raff's Quartet no. 5. The libraries and music stores in New York were searched for the score, but none could be found. Toscanini, who had not seen the music for decades, wrote down all the orchestral parts for the entire movement. Much later, a copy of the score was discovered and compared to Toscanini's manuscript.

He had made exactly one error! But is Toscanini like the rest of us?

False Memories

The preceding case histories and our own common experiences have led many of us to assume that memory is much like a tape recorder or video recorder, holding a perfectly accurate record of what has been experienced. Nothing could be further from the truth. Memory is extraordinary, but it is far from perfect. A classic case in point is John Dean's testimony to a congressional committee about his conversations with President Richard Nixon and others concerning the Watergate cover-up. The first meeting he held with the president was on September 15, 1972. Dean described this and other meetings in astonishing detail in written testimony prepared later for a congressional committee. There was no way to check the accuracy of Dean's memory at the time. But in 1974 the president released transcripts of the tape recordings he had made of these meetings.

Ulrich Neisser, a leading authority on human memory, compared Dean's testimony of the September 15 meeting with the tape transcript of the meeting:

Comparison with the transcript shows that hardly a word of Dean's account is true. Nixon did not say any of the things attributed to him here: He didn't ask Dean to sit down, he didn't say Halderman had kept him posted, he didn't say Dean had done a good job (at least not in that part of the conversation), he didn't say anything about Liddy or the indictments. Nor had Dean himself said the things he later describes himself as saying: that he couldn't take credit, that the matter might unravel some day, etc. (Indeed, he said just the opposite later on: "Nothing is going to come crashing down.") His account is plausible, but entirely incorrect. In this early part of the conversation Nixon did not offer him any praise at all, unless "You had quite a day, didn't you?" was intended as a compliment. (It is hard to tell from a written transcript.) Dean cannot be said to have reported the "gist" of the opening remarks; no count of idea units or comparison of structure would produce a score much above zero.

But despite all the inaccuracies, the basic message of Dean's testimony, that President Nixon knew about the break-in and the cover-up, was true. So his memories did at least reflect reality.

A more serious issue is whether people can be made to remember things that did not really happen. Can false memories actually be implanted? Elizabeth Loftus, a leader in the study of human memory and its foibles, has explored this issue in depth, as we will see later. Here we give one rather charming example that occurred recently. This involved Alan Alda, who is known best as Hawkeye Pierce from the TV show M*A*S*H. What people may not know is that Alda is a lifelong science buff and host of Scientific American Frontiers, a television program dedicated to communicating scientific theories to the public.

Alan Alda visited Loftus at the University of California, Irvine, to work on a show about memory. A week before Alda arrived, Loftus sent him some questionnaires, ostensibly designed to learn about his personality, in particular food preferences. When Alda met Loftus, she explained to him that she and her colleagues had analyzed the data he sent back and discovered that Alda had once gotten very sick after eating too many hard-boiled eggs as a child. (So far as Loftus knew, this had actually never happened.) Later, Loftus and her researchers had a picnic lunch with Alda. There was a smorgasbord of delicious food, most importantly some hard-boiled and deviled eggs. When offered some of these eggs, Alda refused to eat them. Was this because Loftus had induced in him a false memory about his childhood and eggs? In any event, Alda's avoidance of eggs on that occasion was filmed and is a part of the Scientific American Frontiers program on memory.

The Many Varieties of Memory

One of the major achievements of modern memory research is the discovery that there are several different kinds of memory systems with different properties and different brain mechanisms. A convenient classification of these forms of memory is shown in Figure 1-1. The rest of this chapter describes the main features and properties of these different memory systems and uses them to introduce the major phenomena of memory that this book will discuss.

Explicit Declarative Memory: Episodic and Semantic

Larry Squire, of the University of California, San Diego, has argued eloquently for the basic distinction between declarative and nondeclarative forms of memory (Figure 1-1). Declarative or explicit memory is what most people mean by memory. The words "explicit" and "declarative" here signify the ability of individuals to consciously and deliberately access and describe the contents of their memory. Even here there are two different aspects to explicit memory. The first is autobiographical or episodic memory, the memories of your own experiences. The second is semantic memory, the sum total of knowledge you have-your vocabulary, understanding of mathematics, and all the facts you know. The distinction between these two is easy enough to see in Table 1-1.

Endel Tulving, of the University of Toronto, has made the difference between semantic memory and episodic memory into something more than a matter of definition. His conception of episodic memory puts it at the center of the highest human mental capacities: It is the ability to consciously and deliberately perform "mental time travel." This ability can be seen in any example of ordinary, everyday recollection. One day we asked a colleague to write a narrative description of everything he could remember about his trip from home to campus that morning. What he produced appears in Box 1-1. In one sense this act of recollection is not extraordinary because any mentally normal person is capable of it. In another sense it is extraordinary: A very large amount of information was stored and maintained in memory, without any intent on the part of the subject to memorize or retain it. Note also that what he remembered did not consist of striking, unusual, emotional, or important events. Most of it really has to be called mundane. Yet there it is in memory. Try this kind of recollection yourself and you will find that you also have the strong subjective sense that what you are recalling is accurate. Try this kind of recollection for yesterday morning's events, and you will quickly discover another characteristic of the ordinary workings of episodic memory: swift forgetting!

(Continues...)

Excerpted from Memoryby Richard F. Thompson Stephen A. Madigan Copyright © 2007 by Princeton University Press. Excerpted by permission.
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Edition details

• Publisher: Princeton University Press
• Publication date: 2007
• Language: English
• ISBN 10: 0691133115
• ISBN 13: 9780691133119
• Binding: Paperback
• Edition number: 1
• Number of pages: 288