Most people save something for pleasure and profit. It could be Hummels, saltcellars or even beer cans from long-closed breweries.

Then there are pack rats. They save everything. Doorknobs in their homes are circled with elastic bands. Ticket stubs from Bullets', Caps' or Redskins' games pile on the bureau top and resemble the Great Pyramid of Giza. Newspapers, paper bags, matchbooks, letters or old corsages are stashed everywhere. Most items are financially worthless, while some do have sentimental value. Nonetheless, the pack rat covets each item as though it was a gold doubloon.

Pack rats can't throw anything away.

Actor Roddy McDowell saves all the Christmas cards fans send him. Some go back 20 years. "I can't bear to throw them away," he explains.

Boston sports attorney Bob Woolf's office walls are hung with former Red Sox slugger Carl Yastrzemski's bat, the basketball given to him by Celtic Larry Bird, Patriot Doug Flutie's jersey and other sports memorabilia.

Frances FitzGerald, author of Fire in the Lake, a critically acclaimed novel about Vietnam, saved three pieces of Vietnamese paper money and a menu from a 1966 dinner she attended in Manila as a guest of former Philippines president Ferdinand Marcos.

And Rose Kennedy still has the dance cards from her debutante days in 1910, according to Doris Kearns Goodwin, author of The Fitzgeralds and the Kennedys.

We're all collectors of sorts, says an article in the current issue of Psychology Today. The authors, researchers Lynda W. Warren, a psychologist at California State University, and Jonnae C. Ostrom, a clinical social worker, report, however, that there is little psychological literature on collecting or hoarding by humans.

"Initially, psychologists thought of hoarding as a curiosity. They pretty much overlooked or dismissed it as harmless behavior. Most people who save things are in the middle of the psychologist's curve," says Warren.

"But hoarding can be serious in its excessiveness, both for the individual and for those who live with hoarders. Life is a daily struggle of choices for the hoarder. He's fiercely attached to items and cannot throw them away. It's traumatic," adds Warren, who admits to saving greeting cards with personal messages.

Warren and Ostrom theorize that early issues of separation and loss affect hoarders.

"Their attachment to items and great difficulty in separating themselves from items suggests reliving an early loss. Did they lose a parent? Or did they have their stuff taken away? Did economic loss or geographic moves create this need to hoard? We'll start researching those possibilities," says Warren.

Since their article, Warren and Ostrom have been deluged with letters from pack rats and their families seeking help. Other psychologists also are exploring hoarding behavior.

"We all treasure some objects," says Dr. Michael Mirbaum, professor of psychology at Washington University, St. Louis, Mo. Our attachment, he says, is financial or emotional. Diamonds or even old beer cans might eventually mean cash; while Dad's pocket watch or ticket stubs only pay emotional dividends.

Tom Cottle, Harvard University psychologist and television talk show host, says, "The pocket watch, even if it doesn't run anymore, or is something that belonged to a loved one, is our way of keeping a piece of that person. It's priceless no matter what happens."

Treasuring Dad's pocket watch or a letter from a loved one is within the normal realm of saving. While most objects have little value or meaning to anyone else, to hoarders, however, each item is a talisman to guard with their lives.

The reason and degree of attachment and the ability to let go, if necessary, distinguishes whether such saving is normal or pathological. According to Dr. Edna Foa, director of the Center for Treatment and Study of Anxiety at the Medical College of Pennsylvania, hoarding can be harmful if the object is saved out of fear that it will be needed in the future, but it hasn't been used for a decade.

The hoarder can't distinguish what is important enough to keep, so he keeps everything. Most of us save bags from the grocery or some fancy boutique, she points out. "If we use those bags to take out the trash or carry clothes to the cleaners, that's positive, healthy behavior. But if we want to keep a Neiman-Marcus bag forever, watch out. That's obsessive-compulsive behavior. It's time to seek professional help," says Foa.

Don't panic just because you have l940s sheet music stacked on the piano, old love letters or menus from European cafe's and bistros on a top shelf; you need not be diagnosed an obsessive-compulsive. The basic keeping of objects can be healthy if the motivation is positive.

For example, we keep something because it recalls a pleasant memory, a person we admire or because it has esthetic value. But, if necessary, we can let go.

Behavior specialists offer myriad strategies to help a hoarder kick the habit, including donating objects to nonprofit organizations, holding a garage sale or asking a friend to thin out the collection.

How does this hoarding mania start? Some say it's insecurity, difficulty in decision-making, anticipating future need, or superstition. Karl Hakmiller, professor of psychology at the University of Connecticut, says collecting is a kind of restraint reduction. "We put ticket stubs in our pocket instead of throwing the things away at the end of the performance. Now, we've made a commitment.

"We have another chance to throw them out at home when we empty our pockets. If, however, we put the item on the bureau, we're hooked," he says.

As items accumulate on the bureau, we gather them up and store them in a drawer or box. "This restraint against discarding builds up each time we have an opportunity to discard the item but do not.

"Now the item is part of a memory. Some of us have to schedule memories. That's why we have knickknacks or mementos around the house or office," continues Hakmiller.

Athletes are particularly superstitious says Washington University's Mirbaum. "To the athlete -- professional or amateur -- who attaches past success to a certain piece of clothing or equipment, the object has mystical power."

The talisman belief can be self-fulfilling. The athlete believes he has an edge; his self-confidence soars; he does well.

Other specialists claim we save objects to increase our self-esteem, to identify with another person, particularly a loved one. Sometimes it's connecting a personal relationship with someone idolized.

The phenomenon of wanting a tangible object is not restricted to loved ones. People struggle just to touch, photograph or get an autograph from a celebrity. "Having an autograph from Sly Stallone, Liz Taylor or Sean Penn, the famous or infamous, makes the individual feel a special connection with the celebrity. It makes us feel we have a piece of that person's identity," says Cottle.

This often starts in childhood. The little girl walks in her mother's high heels or imitates another adult she loves. The boy wears his father's tie.

"Like Linus' blanket, some children become attached to an object of someone they love," says Cottle.

If hoarding begins in childhood, many of us remain kids even as adults, with emotional attachments to objects that fill our closets. "The separation and loss can impact so that a child develops attachments to things rather than people. Thus the fear and trauma at the thought of discarding the items," adds Lynda Warren.

"Bits of information are retrieved from the items collected. The retrieval gives us emotional attachments -- pleasant, like the thoughts of a good friend, or maudlin, like grief over a loved one," says Hakmiller.

Newspapers are a favorite of compulsive hoarders. They are a concrete manifestation of the lives we live and the world around us, say psychologists. The saver thinks he'll need to find an article in that pile to corroborate his ideas or comments. If he did need a clipping, he'd never be able to find it in the ever-growing stack of papers.

The case of the deceased Marcus twins in New York is a bizarre example of pathological hoarding. "These gynecologists saved everything in their magnificent Manhattan town house. Newspapers were stacked to the ceilings throughout the house. To move from room to room, the Marcus' created a rabbit-warren of tunnels," says Dr. Philip Levendusky, director of the Behavior Therapy Unit at McLean Hospital in Belmont, Mass., a facility connected with Harvard University.

"Some people can't let go," says Harvard's Cottle. "They doubt themselves." Cottle admits that he used to save his mail, especially hate mail. He couldn't destroy it. Sometimes he even answered it. "As I went on in analysis, I stopped keeping hate mail," he says.

Fan mail, however, is another story. "I keep fan mail. We all need flattery from time to time."

Laura White is a free-lance writer based in Boston.