If I close my eyes and think of that moment more than 40 years ago when I learned that President Kennedy had been assassinated, it's as if it were happening now.

It was right after lunch. I was walking to Spanish class, when Heidi Herman passed me in the hall. She was laughing, and said, almost over her shoulder, "Bang! Bang! Someone shot the president!" She thought it was a joke. She was wearing a white cotton shirt and a navy blue skirt—that's what we all wore on Fridays to support the football team. When I arrived in Spanish class, the teacher, Mrs. Goode, sent me to the audio-visual room to get another student, Steve Aronow, who was watching TV there. That's when I knew the president really had been shot.

We all have these kinds of "flashbulb memories," startling in their clarity and detail. These memories are always personal, specific, tied to a certain time and place, and usually have an emotional component. They were first described in a 1977 study that focused on memories of the JFK assassination, a line of research that, along with dramatic advances in neuroscience, is helping to define a new direction in the study of human memory. It's a field that asks intriguing questions, such as, Why do we recall some things and not others? What roles do gender and culture play in what we remember? And what functions does memory serve?

In 1981, David Pillemer was an assistant professor of psychology when President Reagan was shot. "Drop everything else," he was advised by a mentor from his undergraduate days who happened to be visiting at the time. "Follow up on this."

He took her advice, interviewing people within days of the shooting and then again seven months later, producing the first follow-up study of the 1977 research that defined flashbulb memory. Pillemer found that most of the study's subjects retained detailed personal memories about the Reagan-shooting episode, and that their memories changed little over time.

If it had been a decade earlier, it's doubtful that either Pillemer or his mentor would have considered the project. "Before the 1970s, memory research focused on access and accuracy," says Pillemer, the Dr. Samuel E. Paul Professor of Developmental Psychology at UNH. Research tended to be laboratory-based and tightly controlled. A lot of experiments dealt with rote memorization, with subjects being asked to try to recall long lists of nonsense syllables.

The "I-remember-when..." kind of memory—a particular conversation with your minister that changed your life, praise from your 10th-grade teacher for a high school essay, the night you first met the person you would marry—these and other memories of personal episodes might be good for novelists and psychoanalysts, but in mainstream memory research 30 years ago, they were dismissed as anecdotal and irrelevant.

In the 1970s, some psychologists began to shove open the laboratory doors and take their memory studies into the real world. They didn't reject laboratory studies out of hand, but they wanted to understand memory in context, the way it happened outside the confines of a lab. They wanted to probe the influence of gender, culture and conversation on memory, and to explore what role memory plays in how people learn, how their personalities are developed and what life choices they make.

It was a controversial approach. The real world is messy. The field of psychology is sometimes viewed, especially by those outside it, as more akin to philosophy than, for instance, biology. Like sociologists, research psychologists had spent years trying to prove their research could meet rigorous scientific standards with well-controlled, double-blind, quantifiable and reproducible experiments. But Pillemer and other researchers showed that episodic memories could be codified or quantified and therefore studied scientifically.

They also challenged the prevailing belief that people's lives were consistent and predictable. Instead, they hypothesized that memories of specific events or conversations could influence the direction of a person's life. The fact that some memories might not be accurate did not discourage them much. The thinking was that we become the stories we tell about ourselves. As they focused on the development and functions of episodic memory, these psychologists asserted that whether or not stories are accurate, they are important. Just how important is still being explored.

At the same time the field of personal-event memory was finding its footing, a new technology, neuroimaging, was giving scientists an inside view of how memories are stored. Before the 1980s, the only insights into the memories of a working human brain had been extrapolated haphazardly from the results of accidents, brain surgery or autopsies. "We can now study brain function in ways that once were thought to be impossible," notes Robert Mair, a UNH psychology professor who specializes in neuroscience.

When nerve cells in the brain are active, they consume oxygen; the more active they are, the more oxygen they need. Using functional magnetic resonance imaging (fMRI) and other neuroimaging tools, researchers can see that different parts of the brain "light up"— or have the most increase in blood flow—when different memory-related mental tasks are performed.

Once it was thought that there was one unified memory system in the brain for all memories. It's now becoming clear that—as cognitive psychologists have been arguing—there are many kinds of memory and the system is highly complex. "Cognitive psychology helped differentiate types of memory, and now, with the development of better scanning methods, we're able to see that the different types depend on different parts of the medial temporal lobe," Mair says.

Emotional memory, for instance, engages the amygdala. Autobiographical events are stored and recalled in the hippocampus. Examples of other specialized sites are those involved with familiarity versus novelty ("I know I've been here before"), and memories of smells, music, faces and proper names. One part of the hippocampus appears to be designated for spatial memory—the memory of a physical space. More elaborate spatial memory, in the form of cells organized as triangular grids, was reported just this year to be adjacent to the hippocampus.

On a brain map, cautions Mair, there are no double yellow lines marking the boundaries of memory activity. "The whole brain works together for almost everything," he notes. Neuroimaging gives a picture of relative differences in brain activity, and the interactions are still being unraveled.

However, Mair notes, it's fairly clear that not all memories reach the medial temporal lobe. Every minute of the day is full of memories that don't last—the sound of a door opening, the color of a tree you see out the window, the feel of the floor under your feet when you get out of bed in the morning. Based on imaging studies, these short-term memories don't appear to go much farther than the sensory areas of the brain's cortex. They register, but aren't consolidated into long-term memory.

A typical person can usually hold about seven facts at a time in short-term memory, studies show. These short-term memories may last 20 to 30 seconds, and then, unless rehearsed with conscious thought, decay. There's also working memory, the kind of memory that lets you store information briefly while thinking about it. It's the kind of memory that, for instance, allows you to stay with a joke long enough to get the punch line. In the 1988 movie "A Fish Called Wanda," Kevin Kline played a hit man who always asked, right after being given instructions, "What's the second thing?" Clearly, a problem with working memory.

Memories destined to be "keepers" arrive in the cortex and, after encoding, are sent off to the hippocampus and other parts of the brain, where they are processed for long-term storage. Long-term memory falls into two major categories, memories that are context-based—fixed in time and place—and those that are not. Knowing the date of your birth, that the Earth is round, the ocean is salty and George Washington was the first president are examples of non-contextual, "just-the-facts-ma'am," memory. Context-based memory, on the other hand, is episodic and includes autobiographical-event memory. It's the kind that interests Pillemer and his colleague Michelle Leichtman, associate professor of psychology, who holds the Lamberton Professorship.

Psychologists have long puzzled over how—or if—babies have memories. The average person's earliest memory usually goes back no farther than age 3 and a half, and, in some countries, such as Korea, China and India, age 4 or 5. Freudians tended to attribute infant amnesia to sexual repression, a concept not widely held today. "We now know that an infant's mind is not, as psychologist William James thought, 'a blooming, buzzing confusion,'" says Leichtman.

Instead, experiments in the 1990s confirmed that babies retain information from events long before they can talk. In one study with 14- to 16-month-old babies, an examiner picked up a toy box and touched it to her forehead while the babies watched. Four months later, children who had witnessed the behavior were more likely to repeat it when presented with the box than were children in a control group. Leichtman notes that this evidence of infants having memories of events supports the need for establishing routines with babies. "We know that the underpinnings of a child's attachment system has to do with established routines," she says.

But why can't even young children recall events from their infancy? Pillemer suggests that the way we construct memories changes over time, and young memories may be laid down in a nonverbal format. "What cues are there to pull a memory from early childhood if you don't conceive of it now as you did then?"

After language begins to develop between age 2 and 3, so does narrative memory. Children begin to learn what is worth remembering and what isn't. Pillemer and others hypothesize that the way adults, especially parents, talk with young children about their experiences establishes lifelong patterns of memory that play a role in learning, personality and life choices.

"Parents differ in the way they talk with their children," says Pillemer. Some tend toward more elaborative talk—ncouraging the sharing of specific details, asking more open-ended questions. Others are non-elaborative, asking more fact-based, often yes-or-no questions. "The elaborative style gives the message that details are good, useful, worth remembering and worth sharing; that people want to hear them and they are part of what you are. Non-elaborative conversation says that memory is very functional; it lets me know you were safe and followed the rules."

In a study by Leichtman and Pillemer, parents of preschoolers were asked to tape record a conversation they had with their child about a surprise classroom visit that day by the children's teacher and her new baby. A researcher asked the children several weeks later what they recalled of the visit. When compared, the taped conversations showed that children whose parents had elaborative conversation styles remembered the most details several weeks later, especially the details they had discussed with their parent.

These differences in autobiographical-event memories are greatly influenced by culture. "Chinese babies are not born with less narrative proclivities than European babies," says Leichtman. "But the environment helps prune what happens at the level of the brain, and by age 4, children have already learned a narrative style that will dictate what they retain about events in their lives."

For instance, she says, if you ask a Chinese child to describe what happened at bedtime the previous night, you're likely to hear a list of tasks: "I washed my face, brushed my teeth, heard a story and went to bed." The same question posed to an American child might elicit a long narrative about a single thing that happened around bedtime. The researchers speculate this might have to do with the difference between a culture that emphasizes collectivity versus one that prizes individuality.

Outside influences can also create memories of things that may never have happened, a finding that has had wide implications. Several studies in the 1990s indicated how open children are to false memories. One study, coauthored by Leichtman, presented preschoolers with several events the children had never experienced, such as getting a finger caught in a mousetrap. With repeated questioning, 58 percent of the children volunteered personal memories of at least one of the events, and a quarter recalled the majority of events happening to them. The legal implications of these studies were immense, since in a number of alleged abuse cases in the 1980s and early 1990s, testimony by children sent day care workers and parents to jail. "Realizing that children's memories are highly suggestible has dramatically changed the way their testimony is collected and viewed in legal cases," says Leichtman.

Young children are not the only ones who may have malleable memories. In the 1980s, a form of psychoanalysis called recovered-memory therapy flourished as a way to help patients remember past abuse or trauma. Since then, the practice has been challenged by a series of studies that indicate some people, especially those with vivid imaginations, are prone to false memories of early childhood incidents.

Even loaded words can change the interpretation of a memory. Pillemer tells of a study that asked witnesses to an accident to speculate how fast a car was going. When asked, "How fast was the car going when it smashed into the other car?" the estimate was considerably greater than when asked, "How fast was the car traveling when it collided with the other car?"

Parents tend to have more elaborate conversations about memories with daughters than sons, according to Pillemer. This, he and Leichtman say, might be part of the reason girls tend to be more elaborative and to tell more autobiographical-event stories.

A few years ago, Leichtman equipped several teenagers with tape recorders to capture their day-to-day conversations and then analyzed them for content. "Girls had a dramatically greater incidence of referring to past events, and they did so in a more elaborative and dramatic way than the boys," she reports. Pillemer notes that there has been some preliminary neuroimaging that indicates women "might be better wired for episodic memory and men better wired for general memory."

A current focus of Leichtman's and Pillemer' research is the puzzling question of why, beginning in middle school, boys tend to do better in math and science courses than girls. Research indicates that a lot of learning—grade school through college—is cued by personal-event memory. For instance, in one study, a second-grader was asked how she had remembered on a test that a thermometer contained mercury. "I remembered that Mr. B asked what's in a thermometer," she said, "and Tony put up his hand and said it was mercury... I thought Tony had to be wrong. I thought mercury was just a planet."

In addition, when students use episodic memory—remembering information in the context of a particular event—to get the right answer on a test, the answer is still remembered six months after the test, even if the original episode is not, Pillemer said. He adds that one large-scale study showed girls do better in chemistry when there are more laboratory sessions, while an increase in the number of labs did not affect the overall course performance of boys.

Pillemer and Leichtman have proposed a large study on the effect of narrative teaching techniques in math and science classes. They think girls may be turned off by a strict focus on abstractions, formulas and procedures. "It feels alien to them," says Pillemer. "Anecdotally, male principals we've talked with are skeptical, but female principals have understood, saying, 'Yes, that's what girls want to do, tell their own stories.' The women see this as a possible solution to keeping girls engaged in math and science."

Another current focus of Pillemer's research has been the relation of memory and self-esteem. In a series of studies, his research team asked people to describe specific episodes at different times in their lives that made them feel especially good and especially bad about themselves. They found that the negative episodes usually involved interpersonal relations, such as letting down a friend, teasing someone or not sharing. Positive events, on the other hand, usually involved achievement, such as scoring high on a test, learning a skill or getting a job promotion.

He explains the pattern by noting that not belonging—feeling isolated or alone—is a basic human fear. "But once you belong, there's no inherent need to have even more friends." On the other hand, there's a complementary need to achieve, to get ahead to be masterful. This finding, he thinks, could have practical application in parenting and school counseling. He illustrates with a story: "My daughter was very social through her sophomore year in high school. But in her junior year she became very studious, and not nearly as social. I asked her how she could make that shift and she told me that she had a baseline of friends she knew she could count on and that allowed her to do 'the achievement thing.'"

What happens to memories after they are processed for long-term storage is unclear, says Mair, although he adds they are probably stored diffusely throughout the brain. How they are retrieved is also an ongoing memory riddle, one of increasing importance to members of an aging boomer population who fear losing, if not their minds, at least their memories.

Popular media, and even some scientific journals, are full of studies on how to have a better memory. One French study, reported in the journal Neurology, found that women, especially older women, who drank at least three cups of coffee a day performed better on memory tests. Mair points out that coffee and other stimulants may help memory just because they make people more alert; just as your mind usually works better if you challenge it and if you get enough sleep.

But the most tried-and-true way to remember things is the same way you get to Carnegie Hall—practice. "It's not jazzy," says Pillemer, "but it works. We remember things we repeat—things we go over in our minds, and out loud."

Despite the emphasis in magazines on improving memory, a lot more is known about memory consolidation than about memory retrieval. "We still don't know what memory is," Mair says of the elusive unit of memory called a trace, or engram. It's probably not a protein, since memories can last 80 years or more and proteins have short lives. The current assumption is, he says, that when memories are preserved across time there is a molecular change that affects synaptic strength. Synapses are the connections that pass signals between nerve cells. Since the human brain has 100 billion nerve cells, or neurons, each with thousands of connections to other neurons (by one estimate, it has 16 quadrillion neuron connections, with new ones developing all the time), unraveling its molecular pathway will be a monumental challenge.

But perhaps not too monumental. A recent issue of Scientific American included a story on research that has tracked the activity of more than 200 individual neurons in a specific part of the hippocampus known to play a role in forming memories of events and places in both people and mice. Lab mice were exposed to a series of alarming but not painful experiences—a puff of air on their backs, for example. An examination of their neuron firings identified cliques of neurons that fired in response to different aspects of the event, including things as specific as whether the mouse was in a black or blue box. The researchers were able to tell from the neuron firings which experience the mouse had. Someday this research might provide the basis for reading human minds—understanding, perhaps, the thoughts of someone who can no longer communicate because of disease or accident. For now, the research offers tantalizing insights into how memories may be organized and stored.

However, even if the code for memory organization is deciphered—the Holy Grail of cognitive psychologists 30 years ago—scientists still face a mountain of questions about memory, ranging from its molecular structure to how it is stored; from its role in personality and creativity to its function in civilization. The one thing that appears to be certain is that the answers to these questions will require the work of both neuroscientists and cognitive scientists working with real people and real memories.

Pillemer knows he will never grow bored with this particular line of psychology. "Many of these questions," he says, "are so basic to understanding how human nature works." ~

C.W. Wolff is a freelance writer who lives in Kittery, Maine.

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