OUT OF THE blue, the man in Santa Cruz, California, received notice: His daughter, accusing him of incest, was suing him for hundreds of thousands of dollars. The daughter, a college graduate who worked as a technical writer, claimed that while her father sexually abused her from infancy until she was 18, she repressed the memories until she was 26 and in individual and group therapy. There, she recovered explicit memories of abuse by her father that occurred to her as early as six months old.

"Repressed memory" cases like that against the Santa Cruz man are lately flourishing in America's legal and journalistic landscape. While no one has an exact figure, academics say hundreds of such cases are currently being considered in the courts. But are those repressed memories real? After asking that question at meetings of the American Psychiatric Association and elsewhere, I've been the recipient of hate letters, hate voice mail, hate e-mail on my computer: "How could you, a woman, be saying these things?" "I'll bet you think the Holocaust never happened, either."

Most often, though, I'm accused of doubting the reality of all child abuse. I don't. I do, however, doubt one special class of "memories": those that emerge in adulthood after extensive "memory work" -- therapeutic hypnosis or age regression or suggestive questioning or guided visualization or sexualized dream interpretation or any of a number of other suspect techniques. These techniques have led to the surfacing of "memories" of child molestation in women, like the daughter in Santa Cruz, who have spent their lives thinking they had a happy childhood. Yet not a single piece of empirical work in human memory supports the authenticity of claims of memory dating back to six months of age. And research on later childhood amnesia raises many questions about repressed memory, too. It is well known that humans experience a poverty of recollections of their first several years of life. Contemporary cognitive psychologists place the end of childhood amnesia at the age of about 3 or 4.

One study showed that few Americans who were younger than 3 recalled any information about where they were when they heard about the Kennedy assassination, although most people who were over 8 at the time had some recall. While one recent study from Emory University suggests that some people might have a memory for a hospitalization or the birth of a sibling that occurred at age 2, even these "memories" could be the product of family stories.

What about the repression of memories, even of events occurring later in life? Again, there's little science to support the idea that trauma that is repressed can return decades later in pristine form. To the contrary, research psychologist David Holmes of the University of Kansas reviewed 60 years of research and found no controlled studies showing that an event can be accurately reproduced in memory after a long period of repression. Moreover, studies of children who have experienced parental murder and other atrocities show that the children are continually flooded with pangs of emotion about the incidents.

The memory dating back to age six months that formed part of the basis of the case against the Santa Cruz man does not pass the test of science. Where, then, would this false memory come from? The answer requires an inquiry into the modern science of memory distortion. Since the mid-1970s at least, I and other research psychologists have conducted hundreds of studies on the creation of false memories through exposure to misleading information. The resulting body of research shows that new, post-event information often becomes incorporated into memory, supplementing and altering a person's recollection.

Many studies show how people can be led to believe they've witnessed something when in fact they did not. For example, in one study by Jeffrey Haugaard and his colleagues at the University of Virginia, children age 4-7 were led to believe that they saw a man hit a girl (he hadn't) after hearing the girl lie about the assault. Not only did they misrecall the nonexistent hitting, but they added their own details -- it happened near a pond, inside the girl's house and so on.

In another study, Los Angeles psychiatrists R.F. Pynoos and K. Nader examined children's recollections of a (real) sniper attack at an elementary school playground. Some of the children interviewed were not at the school during the shooting -- they were already on the way home or on vacation. Yet even the nonwitnesses had memories: "One girl initially said that she was at the school gate nearest the sniper when the shooting began. In truth she was not only out of the line of fire, she was half a block away. A boy who had been away on vacation said that he had been on his way to the school, had seen someone lying on the ground, had heard the shots, and then turned back. In actuality, a police barricade prevented anyone from approaching the block around the school." The memories apparently were created by exposure to the stories of those who truly experienced the trauma.

My own recent research on false memories shows that it is even possible to inject into someone's mind a detailed memory of a childhood event that never happened. The implantation is accomplished by a small suggestion from a trusted family member. Consider what happened when Jim Coan, the chief research assistant on the project, tried to convince his younger brother Chris that he had been lost at age 5 in a shopping mall one day while browsing with his mother and brother Jim. Both mother and Jim attest that this event never happened.

Jim told Chris this story as if it were the truth: "It was 1981 or 1982. . . . We had gone shopping at the University City shopping mall in Spokane. After some panic, we found Chris being led down the mall by a tall, oldish man (I think he was wearing a flannel shirt). Chris was crying and holding the man's hand. The man explained that he had found Chris walking around crying his eyes out just a few moments before and was trying to help him find his parents."

Just two days later, Chris recalled his feelings about being lost: "That day I was so scared that I would never see my family again. I knew that I was in trouble." On day three, he recalled a conversation with his mother: "I remember Mom telling me never to do that again." On day 4: "I also remember that old man's flannel shirt." On day 5 it was the mall itself: "I sort of remember the stores." In his last recollection, he could even remember a conversation with the man who found him: "I remember the man asking me if I was lost."

A couple of weeks later, Chris was reinterviewed about the false memory. He characterized his memory as reasonably clear and vivid, and then expanded on it. "I was with you guys for a second and I think I went over to look at the toy store, the Kay-bee toy store, and we got lost and I was looking around and I thought, 'Uh-oh, I'm in trouble now. . . . ' And then this old man, I think he was wearing blue flannel, came up to me . . . . He was kind of old. He was kind of bald on top . . . . He had like a ring of gray hair . . . and he had glasses."

Finally Chris was told that his "getting lost" memory was made up. Still he clung to it: "Really? I thought I remembered being lost . . . and looking around for you guys. I do remember that. And then crying, and mom coming up and saying, "Where were you? Don't you -- don't you ever do that again."

Examples of such confidently held and richly detailed false memories do not, of course, prove that repressed memories of abuse that return are false. But they do demonstrate a mechanism by which false memories can be created by suggestion. And they help us understand how someone could believe they had a memory for something that happened at six months of age, when in fact they do not. The reason repressed memories have gained such currency in recent years is no mystery. The case against the Santa Cruz man and many more like it began when a grown-up daughter or son walked into a therapist's office seeking help for depression, low self-esteem or any of a number of life's problems. Nearly every one of these cases involves memories of childhood sexual abuse recovered while in therapy -- memories that did not exist, or at least were not remembered, before therapy began.

Of course, detailed memories that turn out to be false don't necessarily come only from misguided therapy. These memories could arise from fantasy, imagination and illusion. They could combine a mixture of borrowed ideas, characters, myths and accounts from outside sources. But as Emory University psychiatrist George Ganaway recently argued at an American Psychological Association meeting, false memories might be unwittingly implanted by suggestions or expectations of a therapist or another perceived authority figure with whom a patient desires attention or approval. Harvard psychiatrist Judith Herman made a similar point in her book, "Trauma and Recovery": Whereas an earlier generation of therapists might have been discounting or minimizing their patients' traumatic experiences, the recent rediscovery of psychological trauma has led to errors of the opposite kind. Some contemporary therapists have been known to tell patients, on the basis of a suggestive history or "symptom profile," that they definitely had a traumatic experience. The therapist then urges the patient to pursue the recalcitrant memories.

In one case in Cleveland, an accused father hired a private investigator to go undercover to his 26-year-old daughter's therapist after the woman reported a recently uncovered repressed memory and accused him of incest. The investigator visited the therapist complaining about nightmares and sleep trouble. According to tapes of the visits, on the third visit the therapist told the investigator that she was an incest survivor. As the investigator reported later, "She then told me that she was certain I was experiencing body memory from a trauma earlier in life that I could not remember. I could not remember because my brain had blocked the memory that was too painful to deal with." When the patient said she didn't remember any traumas, the therapist told her many people -- including Vietnam vets, earthquake survivors and incest victims -- repress such memories. She then recommended an incest-survivors group.

This therapist, like many others, direct clients to popular books on sex abuse such as "Courage to Heal." "Courage" advertises itself as a guide for women survivors of child sexual abuse and is likely a great comfort to thousands of genuine survivors. But for people without any memories, it keeps up the suggestive pressure. The reader is told, "If you are unable to remember any specific instances . . . but still have a feeling that something abusive happened to you, it probably did." On the next page, the reader is told, "You may think you don't have memories, but often as you begin to talk about what you do remember, there emerges a constellation of feelings, reactions and recollections that add up to substantial information. . . . If you think you were abused and your life shows the symptoms, then you were."

That a five-course meal of suggestions can actually lead someone to falsely believe she was sexually abused may be a hard pill to swallow. Hearing the life stories of scores of "retractors" might help the pill go down more easily. Mel Gavigan, for example, got her first false memories of child sexual abuse when she was hospitalized for depression in Long Beach, Calif. Her therapist seemed disinterested in discussing her painful divorce and the fact that she was unemployed. He kept insisting that she had been sexually abused as a child but had repressed it. Mel tried to remember -- she wanted to please her therapist -- and soon came up with stories of rape by her father at the age of 4. She became so convinced that she confronted her parents and reported them to a child abuse hot line. She read "Courage to Heal." Her memories became more detailed, and increasingly shocking and violent. Eventually, with the help of other more sensible therapists, she came to appreciate that her memories were totally false. Believing something to be true when it's not is obviously not good for a patient; it diverts attention from true problems and wastes endless amounts of time and money. But that's hardly the worst of the consequences. When uncritical acceptance of uncorroborated trauma memories fuels false accusations by alleged "survivors," the lives and reputations of innocent people are irretrievably damaged.

Not everyone accused is innocent, of course. The point is that we do not yet have the tools for reliably distinguishing the signal of true repressed memories from the noise of false ones. Until we gain these tools, it seems prudent to urge care in how horrors on the other side of some presumed amnesic barrier are probed. Is this discriminatory against truly victimized people? I don't think so. For uncritical acceptance of every single claim of sexual abuse, no matter how dubious, is bound to have an unintended and tragic consequence: trivializing the true and ruthless cases of abuse and increasing the suffering of genuine victims.

Elizabeth Loftus is professor of psychology and adjunct professor of law at the University of Washington. Her most recent book is "Witness for the Defense" (St. Martin's Press).