COLUMN ONE : A Chain Reaction of Fear : The Pepsi hoaxes raise questions about a puzzling and disturbing phenomenon--the copycat. Why can a well-publicized tampering case or even a violent crime spawn dozens of imitators?

Leilani Rose had reached the snapping point. Her marriage--a four-year nightmare of fights and disturbances that occasionally brought the police--had finally collapsed.

While grappling with a pending divorce, she was out of work, raising two young children on welfare. She managed to pay the rent, as she tells it, but there was little left after that. Groceries were a struggle. Bills piled up.

“I felt like I’d lost everything,” the 25-year-old Davis resident said in an interview. “I felt like I was alone, dealing with my kids, not having enough money . . . not having enough quarters to do the laundry.

“I was crying out.”

So she cried wolf. In a moment’s daring, knowing that there would be risks but never imagining how substantial those risks might be, Rose said she reached for the easiest opportunity to call attention to her plight. She became another link in a chain of apparent hoaxes aimed at PepsiCo.

As did others in cities as far-flung as San Diego, Williamsport, Pa., and Albion, Mich., Rose called the media and police Tuesday to claim that she had found a needle in a Diet Pepsican. Such reports, triggering one of the largest product-tampering investigations in U.S. history, began to fizzle this week like so much stale soda. One by one, many of the assertions have turned into hurriedly recanted stories or arrests.

The events have thrown a national spotlight onto a phenomenon that is troubling and mystifying. Psychiatrists and others have struggled to understand why a single well-publicized act often spawns dozens, sometimes hundreds, of copycats.

Since 1982, when seven Chicago-area people died after taking cyanide-laced Tylenol, product tampering claims have been a common catalyst for other tampering and false reports, often creating widespread fear.

The Tylenol case was followed by many others. One year, it was glass fragments discovered in a Gerber baby food jar; in another, it was rat poison in a Contac capsule.

In an age of mini-cams and satellites, copycats can turn fear raised by a single incident into a veritable hall of mirrors of look-alike cases and false reports. Only a few years ago, when TV and newspapers seized upon allegations that pins had been found in Girl Scout cookies, 500 to 600 calls bombarded the FDA switchboard--all reporting bogus cases, said agency spokeswoman Betsy Adams.

A far more serious form of copycatting involves violent crime, experts say. Cases in point: Sexual assaults in New York’s Central Park and freeway shootings in Los Angeles.

In all forms of copycatting, “the first act often stimulates them, gives them the idea of how they might seek revenge on someone or act out their own (aggressive) fantasies,” said Dr. Saul J. Faerstein, a Beverly Hills forensic psychiatrist who evaluates the sanity of defendants in violent criminal cases. Knowing others are carrying out the same crime “might reduce the fear of getting caught,” he said, because they perceive a feeling of safety in numbers.

Some copycats are thought to be tormented souls, psychiatrists say, dealing with overwhelming problems or unexpected crises. Others may be ill-advised pranksters egged on by friends, or schemers looking for that winning raffle ticket in a high-stakes game of product-liability settlements.

“They are disturbed people,” said Dr. Judd Marmor, former president of the American Psychiatric Assn., who has practiced in Los Angeles for more than 50 years.

He offered another possible motive: anger against big business. Consumers may be expressing hostility toward one corporation--or against the corporate world in general--by singling out a convenient target: In this case, PepsiCo., a monolith that markets Pepsi-Cola and other products around the globe, Marmor said.

“Whenever an opportunity shows itself (to vent their anger), they may take a crack at it,” he said.

Other analysts describe an even more complicated picture. Dr. James Grotstein, a Beverly Hills psychiatrist who specializes in personality disorders, said copycats vary in degrees of malice. Some place tampered products back on store shelves, as in the Tylenol case and later poisoning deaths stemming from tainted Extra Strength Excedrin and Sudafed. Such people may be intensely withdrawn, sadistic personalities.

Their aim is to murder and cause havoc.

“It’s their secret way of getting even with society,” Grotstein said. “They’re the kind of people psychiatrists practically never see” because they keep themselves apart from others, rarely seeking help.

By contrast, the Pepsi hoaxers have gone public with their claims. So far, they have presented no direct danger to others. The complex forces that drive them may include exhibitionism, loneliness or even martyrdom, Grotstein said.

“There may (even) be a certain pursuit of fun: ‘Let’s see if we can get away with this,’ ” said Encino-based psychologist Robert J. Rome, former head of the Los Angeles County Psychological Assn. He said people may not realize the enormous legal and social consequences of the widespread alarm they cause. “There’s a certain parallel to calling a liquor store to see if they have Sir Walter Raleigh in a can.”

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With such a puzzling array of motives, investigating cases and quelling public concern is very difficult, federal officials say. Adams, the FDA spokeswoman, even declined to discuss details of many tampering cases for fear of inspiring other copycats. Nor would she be specific about the number of Pepsi needle cases reported since the first case June 10, although most estimates place the total at about 50.

“If we would say the number is 99,” Adams said, “there’d be somebody out there who would want to make it 100.”

PepsiCo officials, who say they will take a hard line in prosecuting the hoaxers, argue that financial motives predominate. “Nobody’s called us up and said, ‘I’ve found a foreign object in my Pepsi . . . send me $20,000,’ ” spokesman Jeff Brown acknowledged. But he said cash settlement claims were implicit in the dozens of reports made to Pepsi in scarcely a week’s time.

The FDA tried to stem the onslaught by publicizing the consequences of filing a false tampering claim. The felony carries a maximum penalty of a $250,000 fine and five years in prison.

“People rather naively thought a claim was as good as a settlement,” Brown said. “Now that they’ve found out that they trigger a federal investigation and there are severe penalties for lying, they’re getting cold feet.”

In at least a few cases, however, authorities appear to be ruling out a financial motive. Sgt. Nick Concolino of the Davis Police Department, who interviewed Rose only moments after she told her story to a television crew, said he looked extensively into whether she might have been angling for profit. He rejected that possibility in spite of her financial hardship.

“She thought if it generated some publicity locally, it would bring her a little sympathy,” Concolino said. “It didn’t have anything to do with money. She just hadn’t thought this thing out.”

When Rose was confronted with incongruities in her story--the broken sewing needle she displayed was unlike the hypodermic needles reported in nearly every other case--she admitted lying and broke down in tears. For days, she avoided throngs of reporters by staying indoors and went through “her own little hell,” the sergeant said.

In one of her first interviews since the incident, the contrite Rose--who so far has not been charged--talked of writing an apology to PepsiCo and found it difficult to explain her actions. She said she suffered emotional scars from her marriage. Aside from the attention, she had no clear goal in attempting the hoax, Rose said. She got the idea from seeing other claimants come forward, she said.

With the help of police, she has enrolled in a mental health program and began therapy Thursday.

“I screwed up,” Rose said. “I feel so stupid now.”

Oddly enough, that incident surfaced in a city that has been plagued by a relatively high number of false sexual-assault claims in the past two years. Police said they cannot be sure if any of those claims were inspired by a highly publicized case two years ago, in which a bicyclist accused several teen-age skateboarders of knocking her down and raping her.

The alleged attack polarized the town of 50,000, resulting in City Council hearings and outcries for justice on both sides, said Sgt. Jim Harritt, who commands Davis’ sexual assault investigations. The reaction was, “How could that possibly happen in a nice town like Davis?” Harritt said.

Eventually, discrepancies turned up in the woman’s story--an allegedly broken finger, for example, turned out to be uninjured, the investigator said. Police confronted her and she confessed the hoax.

“She never could articulate the reason she did it,” Harritt said. “She did say she was a little embarrassed that she had fallen off her bike, but that was about it.”

Since then, sexual assault claims in Davis have been recanted or deemed implausible in about half the cases, Harritt said. He is skeptical of the copycat theory, noting that considerable time passed between the original incident and some of the later cases.

“Typically . . . the copycats come out real soon,” he said. “I’m not inclined to think it’s a copycat. But I’m sure not everybody agrees with my viewpoint.”

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In Los Angeles, the pattern of copycat crimes is easier to see, forensic psychiatrist Faerstein said. In 1985, freeway shootings became a focal point of nationwide attention. A year later, throwing a brick through a car window and snatching a purse became commonplace enough to earn a name: “a smash and grab.” Not long after that, authorities noted a surge in so-called Good Samaritan assaults, in which assailants victimized motorists with disabled cars.

Then came carjackings. The first wave, which hit Detroit two years ago, officials said, spread here as the copycats saw they could get away with it.

What is surprising about the Pepsi case is the number of apparently law-abiding citizens who became part of the phenomenon, Faerstein said .

“You see single women or people who . . . are lonely and depressed, and finally (they find) a way to be on television and be interviewed,” Faerstein said. “And they see other people . . . getting recognition, and it seems like an easy thing to do.”

In the Pepsi drama, at least, there are signs of a happy ending. PepsiCo stock has not fallen off the board; on the contrary, it closed Friday at 36 3/8 on the New York Stock Exchange, up almost a point from Tuesday, when the scare seemed to peak. Pepsi sales were also up after a dip earlier in the week, company spokesman Brown said.

“Sympathy purchases,” he speculated.

Rome, the Encino psychologist, was part of that countercurrent. The last time he was at the store, he made a point of buying Pepsi. But he made one small concession to persisting fears.

“Even though the Pepsi cans were on sale,” he admitted, “I bought it from a fountain.”