Have you ever thought of cheating on your spouse? What about slapping an obnoxious colleague? Or ramming some jerk on the freeway? Have you ever had thoughts about taboo or wild sex? Or divorce? Or leaving home? What about harming someone close? Or even harming yourself? Then there are the tamer varieties: Do you not fantasize about food, for example, when you are on a diet? Who has not gloated over someone else's misfortune or coveted a neighbor's house, car, or flashy lifestyle when we want to picture ourselves as perfectly content?

Few of us would dispute the notion that humans spend a great deal of time thinking thoughts we'd rather not have.

Most of us will never act out our forbidden impulses. Yet just the fact that we can think such thoughts may be so disturbing that we make Herculean efforts to repress them, to keep them secret. "I couldn't even tell my husband," recalls Beth, a gentle West Coast mother of three, after experiencing vivid thoughts about hurting her own children. "I spent a lot of time asking myself, 'What does this mean? Am I sick?'"

For as long as humankind has celebrated the creative powers of the mind, we've been forced to confront the darker side of the imagination: thoughts so mortifying, so frightening, so contrary to social custom and our own principles that we recoil in disgust or fear. In 1852, nearly three decades before the rounding of modern psychology, author Herman Melville offered one of the more poignant observations on the life of the mind. "One trembles to think," he wrote, "of that mysterious thing in the soul, which...in spite of the individual's own innocent self, will still dream horrid dreams, and mutter unmentionable thoughts."

In times past, we blamed these dark impulses on the Devil, or on our own weak moral character. We regarded thoughts as but a step away from deeds, and admonished ourselves--or were admonished by others--to squelch the inappropriate notions at every turn. (No coincidence, surely, that five of the seven deadly sins--anger, avarice, envy, greed, and lust--refer specifically to states of mind.)

Even today, after more than a century of scientific exploration of the mind, Melville's "unmentionable thoughts" still raise vexing questions. What causes them? Do they reflect the "real" us? Should they be read as warning signs? Are some thoughts truly off-limits? If so, when does a thought cross the line, and how should it be dealt with?

We know the dangers of denial, and we understand the importance of accepting even the less-than-perfect parts of ourselves. Yet in a culture obsessed with, and increasingly defined by, stories of psychological dysfunction, and in a century punctuated with premeditated atrocity, some of what our own brains conjure up still has the power to terrify us. "For a lot of people, it's like discovering they have an animal inside them," says University of Washington sociologist Pepper Schwartz, Ph.D., who studies sexuality and sexual fantasies. "Oftentimes the feeling is 'My God! Am I one of those weirdos you read about in the paper?'"

Debated for centuries as a moral or philosophical question, the dilemma of forbidden thoughts has since become a compelling psychological subject, and research is yielding some intriguing, if not altogether reassuring, data. Forbidden thoughts--thoughts we feel we shouldn't have because they violate unwritten, yet ingrained, cultural codes--are universal, although the specific content varies across cultures, populations, and historical periods. Unwanted sexual fantasies, for example, typically involve behaviors our culture tells us are inappropriate, such as adultery,homosexuality, incest, and rape. Forbidden thoughts we might have about other people often involve stereotypes, which society frowns upon. Forbidden thoughts have an intuitive quality to them: It's the things we're not supposed to think about that often seem most alluring.

They're clearly linked to our decision-making mechanisms, our ability to distinguish "right" from "wrong," and our capacity to avoid dangerous, unfavorable outcomes. They may also be associated with our creative processes.

However, they can spin wildly out of control. In extreme cases, forbidden thoughts may become so powerful that they break out as actual behavior. More often, though, they get "stuck," become virtually impossible to dispel, and wreak havoc on our mental and physical health.

Much research has focused on the process of thought suppression--that is, on the ways we try to banish unwanted thoughts--and on the consequences of suppression. But researchers have also investigated how and why certain thoughts become forbidden in the first place. What emerges is an intriguing and complex picture of the mind, encompassing everything from genes and neurotransmitters to self-esteem and "family values." Ultimately, the dilemma of forbidden thinking rests on the courage to believe in ourselves.

WIRED FOR WORRY

Studies suggest that our individual vulnerability to forbidden thoughts is partly inherited, and that some of us are simply "wired" to dwell on worrisome thoughts. Yet studies also show that nearly all of us can be made vulnerable through a variety of external influences--influences that, in many cases, are intensifying. In fact, some psychologists speculate that our culture's increasingly fluid and permissive value systems may paradoxically be rendering us more vulnerable to forbidden thoughts--and less able to cope with them.

"At one time, we had much narrower standards of what thoughts were right and wrong--and nearly everything was wrong," says the University of Washington's Schwartz. "Today, it's far less clear where those lines are." And without those societal boundaries, many psychologists say, people may be over-compensating with unrealistic, self-imposed boundaries--and unwittingly making whole categories of thought "forbidden."

This is especially prevalent in the sexual arena. Ours is a culture that promotes sexual fulfillment and liberation while simultaneously insisting on restraint and "responsibility." Absent any clear standards for "healthy" thinking, some individuals attempt to ban their own sexual thoughts with such vigor that they close off an entire sector of experience.

The notion that we somehow create forbidden thoughts may sound strange. Yet many investigators argue that what we commonly refer to as "thought" doesn't begin as either "good" or "bad," but simply as a stream of randomly generated "value-free" images and symbols. "If we were somehow able to build a thought recorder, what we would record would be just about every kind of thought imaginable," argues psychologist David H. Barlow, Ph.D., director of the Center forStress and Anxiety Disorders at the State University of New York-Albany. "Sexual thoughts, violent thoughts, some of them are very strange and bizarre--but for the most part, fleeting. They go in one ear and out the other, and a millisecond later you've forgotten about them."

FLEET IS SWEET

Where things get complicated, and where the trouble can start, is when thoughts aren't fleeting. For a variety of reasons, the brain seizes on a particular thought, holding it up for scrutiny and determining whether action is required. In some cases, however, this scrutinizing mechanism appears to go haywire. The partly processed thought somehow becomes permanent, or "intrusive," and can generate unpleasant emotional or physiological responses. In other words, researchers say, it's not the thought itself that is forbidden, but our reaction to it--a reaction that can involve intense feelings of shame, guilt, and even fear.

Precisely how this fixation occurs is not fully understood, but investigators have identified several main factors that can bring it on. Some fixation, for example, is clearly chemically induced. Research on individuals with obsessive-compulsive disorder (OCD), who appear genetically predisposed to focus, or "ruminate," on painful or strange thoughts, suggests that vulnerability has a neurological basis. Similar conclusions arise from studies on stress, a condition that can temporarily alter neurotransmitter flows and make subjects more likely to fixate on particularly unpleasant thoughts.

These findings could help explain why drugs like Prozac, Paxil, and Zoloft can inhibit or moderate the fixation process. The findings can also help explain fantasies like Beth's, which, according to Barlow and other researchers, are quite common among young, stressed-out parents.

Researchers have also identified certain higher-level cognitive factors that can influence the kinds of thoughts the brain latches on to, and how it interprets them. One factor may be what psychologists call "controllability." Closely related to self-esteem, controllability is the measure of an individual's sense of power, or control, over events in his or her life. The more in-control we feel, Barlow says, the less likely we are to interpret any event, whether external or coming from inside our heads, as worthy of concern or rumination. "On the other hand," warns Barlow, "if you feel that events are essentially out of your control, you're probably going to be much more vulnerable" to forbidden or unwanted thoughts. In other words, the vulnerable individual is likely to "read" more into a forbidden thought, just as a chronically anxious employee, for example, tends to read more into the boss's tone of voice or facial expression.

NO PAIN, NO GAIN

Worse, psychologists say that for low-controllability types, forbidden thoughts can unleash a damaging snowball effect. The more often people experience thoughts they deem uncomfortable or inappropriate, the more battered their sense of control and self-esteem become. And, notes Frank Fincham, Ph.D., a cognitive psychologist at the University of Wales, "how people react to unwanted thoughts depends a lot on his or her level of self-esteem."

Yet clearly, forbidden thoughts aren't simply the product of chemical imbalances or low self-esteem. A more central and complex factor, and one that researchers are just beginning to unravel, is the link between our forbidden thoughts and our larger system of values--our internalized template for judging right from wrong. A forbidden thought is, by definition, one that violates that template, and the resulting pain, researchers say, is part of what helps us to function as social beings. Displeasure over a fantasy of violence or adultery, for example, "may simply suggest that people approach life in a principled way," argues Norman Epstein, Ph.D., a psychologist in the family studies department at the University of Maryland. "If a thought like that pops into your head but you're not bothered by it at all, that could be a problem." The absence of this painful response may help explain some violent and other antisocial behavior.

Moreover, some psychologists see forbidden thoughts as part of the mind's process for testing and reaffirming its internal rules. Rape fantasies--both of raping and being raped--are quite common and are often interpreted by individuals as evidence of serious problems. But Schwartz argues that in many cases the brain may simply be teaching itself about consequences of rape. In the fantasy, Schwartz says, "maybe you're having someone who in real life you could never hope to have, or maybe you're dominating someone in a way that would hurt them." But sooner or later reality intrudes. "You realize the person is scared or is hurt," Schwartz says, "and in your mind, you back away."

Interestingly, just as individuals can "use" forbidden thoughts to explore the limits of their inner selves, many artists and authors use these thoughts to explore the outer limits of their culture. What are works like Henry Miller's Tropic of Cancer or David Lynch's film Blue Velvet (or just about anything by photographer Robert Mapplethorpe) but articulations of their creators's forbidden thoughts? One could argue, in fact, that many artistic, cultural, and political breakthroughs come about in part because an individual is willing to challenge the status quo to, in effect, "think the unthinkable."

Of course, few of us are paid for our unthinkable thoughts. More to the point, our culture offers few constructive rules or procedures for interpreting and coping with forbidden thoughts in a positive way. Instead, we're likely to construe them as unwholesome, as evidence of some deep psychosocial flaw, or as a prelude to antisocial or dangerous behavior. As such, psychologists say, our response is fairly predictable: We try to suppress them, usually with more energy than is realistically necessary, to prevent the worrisome thought from materializing into action.

THE TROUBLE WITH SIN

Again, how strongly and negatively we react can depend on physiological or personality factors. But studies also suggest that past experiences, especially during upbringing, play an enormous role and that individuals from authoritarian backgrounds are far more likely to overreact to, and overcompensate for, forbidden thoughts. Research shows, for example, that persons raised in heavily religious households, where "evil" thoughts are regarded as evil deeds-in-waiting, are more likely than their non-religious counterparts to fixate on thoughts they feel are sinful or otherwise inappropriate. Their "God's will" world view may have produced a low sense of controllability and self-esteem, and thus a higher-than-average sense of vulnerability.

At the same time, such individuals grow up knowing precisely which thoughts are improper and therefore "worthy" of worry. "As a Catholic, there were whole domains of stuff that I wasn't supposed to think about," admits Thomas Borkovec, Ph.D., a distinguished professor of psychology at Penn State University who studies the phenomenon of worry. "When I did, I felt very guilty, and would try very hard to distract myself."

Unfortunately, it is precisely this response--attempting to avoid or suppress a forbidden thought--that can transform such thoughts from useful mental tools into agents of harm. Ever since Freud, psychologists and the lay public alike have understood that suppression of thoughts and feelings can have unintended consequences. But in the mid-1980s, research by University of Virginia psychologist Daniel Wegner, Ph.D., gave a whole new meaning to the word "backfire": the harder one tries not to think of a particular thought or image, Wegner found, the more likely it is to become intrusive and repetitive.

BEWARE OF THE WHITE BEAR

Wegner's experiments were ingeniously simple. He set people in a room with a tape recorder and asked them to say whatever came to mind, with one caveat: They were not to think about a white bear. "People mentioned the bear about once a minute, despite the fact that they weren't supposed to be thinking about it," Wegner says. "They would try all sorts of tricks, but it would keep coming back to them."

Wegner and his colleagues aren't certain why this occurs. He suspects that in suppressing a thought, the mind is still "monitoring" the "contents of consciousness" for any vestige of the painful thought, and is thus more sensitive to that thought. Another theory is that in attempting to distract ourselves from one thought by thinking of another, the brain creates associations between the two thoughts. As a result, the distracting thought actually helps bring back the thought it was intended to mask. Still other researchers theorize that by suppressing a forbidden thought, the brain never gets a chance to fully process the thought. The individual then is never able to see that the forbidden thought is unrealistic and extremely unlikely to be translated into action. In short, without full processing, the thought may remain unresolved and will keep re-emerging in the consciousness for more processing--and more suppression.

Whatever the actual mechanics of suppression, Wegner says, it's an almost automatic response to unwanted or forbidden thoughts. People on a diet, he says, will suppress thoughts of food. Victims of traumatic experiences--accidents, loss of a loved one, broken relationships--will try to suppress painful memories. People with secrets, dark or otherwise, use suppression to keep the knowledge hidden.

Here again, researchers see a snowball effect. We tend to suppress most energetically thoughts that bring us the most pain, Wegner says, and yet, the harder we suppress, the more intrusive and unpleasant the thought becomes. In one provocative study, four researchers--C. Neil Macrae and Alan Milne at the University of Wales; Galen Bodenhausen, Ph.D., at Michigan State University; and Jolanda Jetten at of the University of Nijmegen in the Netherlands--found that subjects attempting to suppress stereotypical, or prejudicial, thoughts made the thoughts stronger than before suppression. Psychologists call this unintended result an "ironic" process.

"The act of trying not to stereotype others ultimately increases the use of stereotypes," explains Bodenhausen. Other studies confirm his point: researchers have shown that governmental attempts at banishing Western thoughts from public discourse, as is the case in Iran, actually increase the number of times such ideas are discussed and, presumably, thought about.

In another study, Constantina Giannopoulos, M.A., and Michael Conway, Ph.D., at Montreal's Concordia University, asked subjects to suppress thoughts of food. They found the task far more difficult than did subjects under no such prohibition. In general, says Wegner, "the mental conditions we fear the most are the ones we tend to create through this process. It's a paradox, like trying desperately to get to sleep the night before something important."

CONFESS, DON'T SUPPRESS

What is startling even to researchers, however, is just how serious the consequences of suppression can be. In a well-known case, convicted serial killer Jeffrey Dahmer confided to psychologist Judith Becker that he had been tormented as a child by thoughts of torturing animals. (Clearly Dahmer was plagued by more than just thought suppression.) "He found these thoughts repulsive and attempted to suppress them," notes Barlow. "And he basically ended up being haunted by them for the rest of his life."

Not unexpectedly, many researchers and therapists suggest that the way to loosen the grip of forbidden or unwanted thoughts begins with the de-suppression of them. Wegner and psychologist James Pennebaker, Ph.D., at Southern Methodist University, advocate confiding one's forbidden thoughts. They have found that subjects who do discuss their thoughts can feel better both emotionally and physically.

Part of it may simply be getting a troublesome thought off our "chests." But research by Roxane Cohen Silver, Ph.D., a psychologist at the University of California--Irvine who has worked with Vietnam vets and other trauma survivors, believes that sharing helps us realize we aren't alone in our anguish, that others have unwanted or forbidden thoughts as well. This, she says, can help reduce the stigma that often creates the forbidden thought in the first place. "The more that individuals who have experienced trauma think that their [mental] situation is unique," Silver says, "the less they're likely to talk about it, and the less likely they are to receive validation of their thoughts."

Unfortunately, de-suppression is only half the battle. In the first place, it's often hard to find someone to listen. Those we're willing to talk to--spouses, relatives, close friends--often lack the expertise or patience to realistically assess our thoughts. Indeed, friends and spouses may simply not be able to cope with especially disturbing thoughts. Generally, says Silver, research has shown that the more horrific and socially stigmatized the thought, the smaller the willing audience, and the more often the individual experiences the unwanted thoughts. The only place left to turn is the counselor, minister, or other trained listener--an option with its own social stigma attached.

WHAT LURKS IN MURK

The more daunting hurdle, however, may be finding new, more realistic mental "rules" to replace those that helped generate the forbidden thoughts. To be sure, rules against thoughts of, say, murder or child abuse still apply. But what about thoughts like divorce? You may have been raised in, and internalized the rules of, a culture where the "D-word" was never even spoken aloud. To even think of divorce was to admit your marriage was imperfect, that you were already planning to leave. Today the "rules" for thinking about divorce are vastly different. While the consequences of failed marriages remain clear, so do the dangers of staying married at all costs. Divorce is simultaneously stigmatized and regarded as a thinkable, potentially healthy option.

The point, psychologists say, is that while a too-rigid value system can create vulnerabilities to forbidden thoughts, so, too, can a value system that is ill-defined or in a state of flux. This is especially evident in individuals who have begun to question their religious beliefs, to rebel against the authority of a parent or spouse, to resist the cultural attitudes they grew up with, or even to shuck off an old, unwanted self-image. Whatever the objective, many such individuals are, in essence, seeking to let themselves have thoughts that were once forbidden. (Not surprisingly, many of the popular new spiritual and self-help movements specifically encourage their adherents to avoid the terms "should" and "should not" in the context of thoughts and actions.)

CONSCIENCE IN CONFLICT

Such efforts may ultimately be wholesome and liberating. But they may also profoundly contradict many traditional teachings and attitudes, and could magnify confusion--and vulnerability--in persons whose past attitudes maintain a powerful, if unwanted, pull. They may find that the thoughts they want to have--about racial equality, for example--are at some level still "forbidden" by past experience and attitudes. At the same time, thoughts that were appropriate and encouraged under that previous world views--judging others via stereotype, for example--are now inappropriate, and thus also "forbidden."

In a sense, even before an individual has vanquished one set of forbidden thoughts, he or she may be busily creating a new one. "It can be a tough time," says the University of Maryland's Epstein. "You don't have a [belief system] to hold on to. Basically you know what you're trying to leave behind, but you haven't yet figured out what you're going into."

And, in reality, few people are torn between just two belief systems. Western culture, especially American culture, is a rich stew of competing value systems, distinct subcultures, and often radically different notions of "inappropriate" thoughts. What is correct thinking in one subculture may be intolerable in another, causing confusion for people moving between the two. A woman raised in a conservative rural community, for example, may have learned to "forbid" herself from desiring a professional career or equality with men. Yet if this same women moves to an urban, liberal environment where such thoughts are encouraged, she may nonetheless find it difficult to have such "liberal" thoughts without guilt or self-doubt.

Indeed, cultural politics are rife with forbidden thoughts. Many liberal doctrines criticize traditional religion as "thought control," yet themselves set aside whole new categories of thought as "politically incorrect." Consider, for example, the internal conflicts of the "sensitive" male who views himself as respectful of women's rights and feelings and yet finds himself fantasizing about rape. Or consider the conflicts of an avowed feminist woman who finds herself fantasizing pleasurably about staying home with the kids. Or about being sexually dominated!

No category of thought may be as filled with contradictions, and so difficult to judge, as sexuality. We're bombarded daily with provocative images, stern warnings, new and often contradictory theories based as much on politics as science. We're told that sexual feelings are good, but that sexual feelings can get out of control. We're told the reasonpornography is titillating is because our culture "forbids" sexuality, but that watching pornography corrupts our minds. We're told that lust is normal (Jimmy Carter admitted to it), but also that lust is a bad habit. That homosexuality is genetic, but also a chosen lifestyle and a sin. That adultery is fatal, but also a common, survivable social phenomenon. "It used to be that having sexual thoughts about anyone but your wife was wrong," observes Schwartz. "Now, it's as if we've been given more permission."

DO-IT-YOURSELF STANDARDS

Fluid societal boundaries not only make us vulnerable to forbidden thoughts, they simultaneously deny us the tools we need to cope with the unwanted intrusions. The only way to make sense of the chaos, some psychologists say, is not to blindly rely on culture to supply our mental standards. We must be willing to take matters into our own hands. That may mean seeking professional help, especially if we feel a thought is in danger of breaking out. A good rule of thumb: If a thought is causing pain, or interfering with your life, it's probably time to talk to someone.

In severe cases, where an individual is paralyzed by his or her reaction to forbidden thoughts, drugs or intensivetherapy may be needed. In less serious instances, however, treatment centers on helping people to recreate or recover a healthier, more realistic perspective on their thoughts. And while these treatments are often conducted in the controlled environment of a therapist's office, psychologists say, they may also be effectively applied in everyday situations.

PERMISSIVE PERSPECTIVE

Some therapists, for example, give their clients "permission" to think the forbidden thought for a specified period of time each day, which, in less severe cases, allows our normal mental processes to wash away the anxiety associated with it. Others recommend what might be called the Big Picture approach. "What we try to do is have clients step back and look at their life as whole, to be objective," says Epstein. "To what degree are the thoughts having an impact on the way one leads one's life? Do they tend to live by basic principles? Do they tend to treat people in a fair way?" Often, he says, people troubled by forbidden thoughts "have highly unrealistic standards for themselves."

Generally, psychologists say, patients are helped to understand that life's stresses can produce impulsive, unwanted, but not necessarily deadly, thoughts. Work is a common source of forbidden thoughts. But family situations are probably the most fertile. This is particularly true in marriage or live-in relationships, where the work and stress of keeping a relationship together, raising children, managing money, keeping house, and coping with in-laws can occasionally give rise to less-than-savory thoughts about one's spouse.

The key is to consistently strive for a sense of perspective and realism. As Neil Jacobson, professor of psychology at the University of Washington, puts it: "The fact is that to be married to someone is to sometimes think he is an asshole."

Whether we go it alone or seek counseling, psychologists say, confronting our forbidden thoughts ultimately requires courage. Courage to create, and live by, our own rules. Courage to face our own worst fears, and to question our own self-prohibitions with the same intensity and passion with which we question society's rules. But it is also the courage simply to believe in ourselves.

Forbidden thoughts may prevent us from committing heinous crimes and other regrettable acts. They may help us to survive as participants in an intricate social dance. But they can also serve as a means of undermining ourselves, of seeing ourselves in a primarily negative light. In the end, the most damaging "forbidden" thought, the one we have been trained to block at every turn, may simply be that we are really okay. "Most of us have had some pretty off-the-wall thoughts, and when we question ourselves, to some extent that's part of the mental health process," says Seattle therapist Michael Donnen. "But we have to learn to be gentle on ourselves."