Years after she first saw "The Passion of the Christ," Lori Pearson still feels queasy when she recalls the brutally graphic movie about the final hours of Jesus' life.

"After I left the theater I remember feeling physically uncomfortable," said Pearson, a Dublin, Ohio, mother of two teenagers who writes movie reviews for the website Kids in Mind. "It was gruesome torture sequence after gruesome torture sequence. That kind of thing has a tendency to stay with me."

Pearson and her husband, Aris Christofides, started writing highly descriptive online reviews in 1992 to help parents navigate the sometimes confusing nature of movie ratings, but over the years their audience has evolved to include an unexpected group: adults looking to avoid certain types of screen violence themselves.

"We get a lot of email from women who've been victims of sexual violence and don't want to see those kinds of scenes," Pearson said. "We get email from people who've been in a car accident and don't want to see a movie with a car accident. And a lot of people just can't tolerate torture — including me."

Amid the heated public debate over whether violent entertainment causes or encourages aggressive behavior, it's easy to overlook members of the audience who are quietly but profoundly affected by scenes of murder and mutilation in movies and television — the ones who go home and pull their covers over their heads or go out of their way to avoid such fare entirely.

Although it's not often discussed, some people are more sensitive to screen violence than others, both for reasons of physiology and life experience.

In a world where increasingly grisly entertainment is delivered on bigger screens, with more realistic visual effects and in the sometimes assaulting detail of high definition and 3-D, those with more delicate sensibilities may feel under siege. And with violent movies such as "The Dark Knight Rises" and "The Hunger Games" among last year's highest grossers and programs like "Criminal Minds" and "The Walking Dead" scoring some of TV's highest ratings, Hollywood has little incentive to cater to them.

San Francisco psychologist Elaine Aron estimates that 15% to 20% of people are "highly sensitive," a group she identified in the 1990s and published research on in medical journals such as Social Cognitive and Affective Neuroscience and the Journal of Analytical Psychology. Along with being more affected by noises and smells, these same people tend to react more strongly to violent imagery.

"Sensitive people have more active mirror neurons," Aron said, describing a type of nerve cell that neuroscientists have only recently begun to research. "These are the parts of the brain where if you see somebody kick a ball, you feel as though you're kicking the ball yourself. Then there are other parts of the brain that tell you, 'No, it's not you.' But the experience of empathy still happens, and for some people, it's very intense."

Sensitive viewers don't just react while sitting in a movie theater — with a quickening of the pulse and a surge of stress hormones — but long after, often experiencing nightmares or feeling uncomfortable in situations that remind them of the scene.

Anyone who has ever thought of "Jaws" while wading in the ocean or "Psycho" while taking a shower can relate to the indelibility of certain filmed images. But for some people the pictures pose real and lasting problems.

After seeing the 1967 Audrey Hepburn thriller "Wait Until Dark," Joanne Cantor couldn't sleep for days. Cantor, an expert on the psychological effects of media and a professor emeritus at theUniversity of Wisconsin-Madison, was in her 20s and had just moved to Paris. Like Hepburn's character, who is blind and being pursued by criminals, she was a vulnerable young woman in an unfamiliar setting.

Repercussions from media violence, as Cantor found, are more acute when we're young. Imagery we see when we're younger than 13 leaves a particularly lasting imprint, she said, and children under 5 are almost completely unable to differentiate fiction from reality.

In surveys of 530 of Cantor's undergraduate students, 86% reported having some fright symptoms after viewing certain kinds of media when they were under age 13. Some said they couldn't sleep for days, while others reported ongoing discomfort around normally nonthreatening objects or beings, such as clowns or animals.

"Our brains are made to respond negatively to depictions of violence," said Cantor, who also wrote the book "Mommy, I'm Scared." "The fear response is designed to keep us alive. Some people say, 'Why am I such a baby? What's wrong with me? This gives me nightmares, but this is what my boyfriend wants me to watch.' I tell them, 'You're human, there's nothing wrong with you.' Our brains evolved to respond this way before there were movies."

Some of what determines whether an audience enjoys a violent movie is in the genes, but some of it is in personal histories, according to Michael Pluess, a psychologist at the Institute of Psychiatry at King's College in London who studies why some people are more influenced by their environment than others.