Geysers of blood soared toward the sky as the machetes fell upon their victims, showering all who saw them.

Kevin Greutert sat down so he wouldn’t faint. He was attending a funeral ceremony in Sulawesi, an Indonesian island east of Borneo, and ten buffalo had been sacrificed with the sharp blades, “‘Apocalypse Now’-style,” as their legs were bound to each other by rope. Greutert has always been sensitive to blood and would pass out as a child when he saw it, but it wasn’t merely the gore that disturbed him.

“It was the shining, ecstatic faces of the local Torajan people smiling as they watched the animals dispatched,” Greutert recalled to Salon in writing. “I had gotten to know the family that invited me, and some came over to me as I sat on the ground, no doubt pale as a sheet. They asked what was wrong, and I could only vaguely gesture to the fountains of blood spraying ten feet away.”

He added, “They smiled brilliantly and exclaimed, ‘But it’s beautiful!'”

Greutert knows a thing about blood and gore being beautiful: He directs horror movies. His most famous films include “Jessabelle,” “Visions,” “Saw VI” and “Saw VII,” the latter two of which belong to a franchise that is frequently derided with the epithet “torture porn.” Greutert is a specialist in using make-up and other visual effects to create the illusion of graphic horror, even though he still gets queasy around real blood. He recalled that while shooting “Saw VI,” he and his special effects crews would often spend hours in a day setting up a single gory scene. Rubber limbs, blood-filled squibs and blood tubes are attached to actors who rehearse reactions of agony and terror; gallons of (fake) blood are pumped through hoses so they can be sprayed at precisely the right moment.

“Whenever you have to do a gore shot more than once, this usually involves cleaning up the set, replacing the actor’s bloody wardrobe and washing their hair and body off, re-rigging the special effects, and cleaning blood off the camera lens,” Greutert explained. “Sometimes the schedule doesn’t allow for any of this. The pressure to get it right is tremendous.”

It may seem strange that this much craft and artistry is invested in splatter horror. If so many of us are repulsed by bloody violence in real life, why would we want it simulated on the big screen? It is one thing to merely enjoy being scared; horror movies do not have to include gore to be frightening. Yet studios are willing to invest millions in graphic horror franchises from “Halloween” and the Chucky series to the supposed “torture porn” like the “Saw” and “Hostel” universes. What is behind humanity’s macabre love of viscera?

Part of the explanation, psychologists say, can be seen in Greutert’s contrasting responses to real-life and fictional gore. We find it gratifying to experience that which would normally upset us, but from an emotionally secure point of view.

“We get to consume something we see little of in real life, in a controlled and safe environment, where we can test the limits of our emotive response in comfort,” British psychologist Dr. Lee Chambers told Salon by email. In this sense, there is an undeniable overlap between the appeal of horror and the appeal of gore.

“Both are deeply intertwined with the concept of evil, something that again fascinates many of us but we experience minimally,” Chambers explained. “In an increasingly sanitized and protected life, the chance to experience fear and emotional pain can be appealing and a novelty.” Audiences of horror and gory violence also experience pleasure through the release of adrenaline, endorphins and dopamine.

At the same time, there are things offered by gory entertainment — within or outside the horror genre — that are distinct from horror on its own.

“Gore can also be quite desensitizing, but used well it can generate a strong emotional response that becomes a stand out moment,” Chambers said. “But in turn, this can cause us to forget the smaller details around it. Sometimes gore can be used in such a comical way. It opens a facet of evil which is no longer scary, but actually funny to consume.”

Matthew Strohl, an assistant philosophy professor at University of Montana and author of “Why It’s OK to Love Bad Movies,” elaborated on the different kinds of emotions that can be evoked through gore.

“For one thing, gore can elicit a disgust response,” Strohl wrote to Salon. “On leading theories, the evolutionary basis of disgust is that it helps motivate us to avoid pathogens by steering us away from raw viscera and bodily excretions.” A talented artist can draw from this habitual response to advance their story. Strohl pointed to the 2000 horror film “Ginger Snaps” as an example: In that tale, a teenage girl is attacked by a werewolf and must go through puberty while her body changes in unnatural as well as natural ways.

“It draws parallels between puberty and lycanthropy and uses gore effects to evoke a disgust response in part as a comment on the way menstruation can be the subject of ridicule and shame in a high school setting,” Strohl observed. At the same time, not all horror movies use gore for the ostensibly noble purpose of exploring deeper issues. Sometimes a movie seems to be made where the gore is an end unto itself, not a means to that end.

“These are the movies that we aren’t allowed to see as kids, that pearl-clutching commentators tell us are bad and wicked and evil, and that come with warnings for the faint of heart,” Strohl told Salon. “These movies appeal to us in part because they are dangerous and transgressive. Nothing is a surer guarantee that I will go see a movie than outraged controversy or nauseated critics.”

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Did any of those critics have a point, though? Should gory horror movies be regarded as immoral, a charge Pulitzer Prize-winning film critic Roger Ebert made against the classic slasher “Friday the 13th: The Final Chapter”?

In terms of influencing how people treat each other, absolutely not. Indeed, research indicates that horror movies can have a bonding effect. People will often seek out graphic horror in groups, forging connections over their common interest. As they experience stress and fear together (but in a safe environment), they feel on some level as if they’ve gone through a mutual journey. When they return home, they do so not only with those warm friendships, but with an increased capacity to conquer their fears and display resilience during adversity. In many ways, seeing a disturbing horror movie can be a team building exercise or a therapeutic experience.

This isn’t to say that gory horror is completely harmless. Its dangers, though, are pretty much the same as any form of media that can become habit-forming.

“It does have the potential to be unhealthy, especially if overconsumption impacts fundamental aspects of our wellbeing,” Chambers explained. “Due to the physiological reactions of watching horror and gore, we can find ourselves euphoric and highly stimulated, making it much harder to sleep. Due to sleep importance in our overall health, continued disruption can compound negatively.” He added that people who are sensitive to fictional gore and horror may have nightmares, which in turn can increase their overall anxiety.

These are basic physical and mental health questions which, again, apply to any stimulating form of media. In terms of whether gory entertainment is immoral, it is important to note that even if you aren’t watching it in a group, to appreciate artistic quality or to garner some personal reward from it, that’s also okay.

“Not everything needs to be healthy,” Strohl explained. “I can’t imagine anything more boring than a steady diet of art aimed at moral improvement. I want to visit the dark side, and I don’t need to be morally improved while I’m there. Am I worried that a love for gory movies will make me morally worse? No, I am not.”

He added, “I am not a computer that takes in movies as input and spits out a moral outlook as output. I am capable of separating my aesthetic joys from my moral convictions.”

Greutert knows a lot about those aesthetic joys. He mused to Salon that “even the crassest slasher film is speaking in a profound way to our existence as fragile bags of protoplasm protected from the infinite nightmare of deep space by only the thin atmosphere of the earth.” In his mind, they are stand-ins for ancient blood sacrifice rituals such as those which existed among the Aztecs at Teotihuacan’s pryamids.

“Perhaps part of the ecstasy I feel when it all goes right is just professional responsibility and the desire to not waste other people’s time and money,” Greutert explained. “But who can argue with the spectacle of seeing someone realistically decapitated with a chainsaw before your very eyes, and knowing that you orchestrated this modern blood sacrifice, and it will be shared with millions?”