Everyone knows the usual scenarios—the mysterious stranger, the threesome, meeting and making love to George Clooney. But are more varied than we imagine, says Wendy Maltz, a therapist and author of Private Thoughts: Exploring the Power of Women's Sexual Fantasies.

In scripted fantasies—which we conjure while having sex or daydreaming, and which involve characters and follow a narrative—women mostly cast themselves in six roles, found Maltz: the Pretty Maiden (object of another's desire), the Victim (object of or violence), the Wild Woman (initiator of sex), the Dominatrix (who exerts power over others), the Voyeur (who watches others having sex), and the Beloved (who intimately connects with a lover of equal power).

Unscripted fantasies are more fleeting—often triggered by objects in our environment—and focus on images or sensations rather than characters or a traditional storyline. Among women, these often portray the building and releasing of tension—mimicking the sexual response cycle itself—and involve images not usually considered sexual, such as horses galloping, flowers blossoming and releasing perfume, trains cresting hills, or storm clouds gathering and then spilling their water. Men have abstract fantasies too. One man imagined his wife was a diamond, and he a ray of light shining into her.

Fantasies reflect the stimuli we're exposed to during our sexual awakening, says Maltz, the way drug addicts learn to associate the stimuli present when they get high—shot glasses, rock music, drug paraphernalia—with pleasure itself. One subject experienced her first when jumping into a swimming pool, then found her fantasies as an adult all involved water. A girl who first experienced sensual feelings on a swing set might have kinesthetic fantasies. A boy who gets his first erection watching a girl brush her hair might have fantasies involving hair.

Our fantasies also reflect our anxieties, says Michael Bader, author of Arousal: The Secret Logic of Sexual Fantasies. A woman insecure about her may fantasize about driving men crazy with desire—say, inducing a police officer, president, or priest to step out of his normal role—or of having sex while men watch. A woman worried she's too much for a man may fantasize about being overpowered. As one female subject put it, "My desire is like a wave crashing on the shore. I don't want to worry about whether the shore can take it."

Powerful men, meanwhile, may fantasize about relinquishing that power and being dominated. Studies show men are actually more aroused than women by fantasies of being restrained, dominated, or spanked, says Bader. As sex researcher Nancy Friday put it in Men In Love, the secret wish of men is "to be done to."

Night Vision

MALE FANTASY

Graphic and visual

Impersonal relationship dynamics; multiple or interchangeable partners.

Focus more on body parts and explicit sex

FEMALE FANTASY