When "The Exorcist" was released in 1973, the film scared audiences so bad that people were fainting, vomiting and reporting terrifying nightmares. But the real question here is, Why did this happen considering their have been equally scarier films and stories told on the screen before it?

According to Movie Pilot, the Academy Award-winning film director William Friedkin and screenwriter William Peter Blatty used a few familiar tactics to increase the tension in the film.

It might be worth noting that Blatty, who also wrote the novel of the same name in 1971, previously had served as the policy branch chief for the U.S. Air Force in their Psychological Warfare Division. That basically means that on top of creating effective propaganda in warfare situations, he was also chief of a division that studied the effects that certain psychological tactics had on people, especially negative effects.

Given that the movie was marketed as a horror movie that could potentially scare you to death, people flocked to these crowded movie theaters, if for nothing else, to see what all the fuss was about. That, of course, was where the added elements of fear were instilled into the movie.

In terms of subliminal messaging, that can be dismissed if the viewer is aware of the image seen. So it may be a stretch to call these images subliminal. But there were indeed flashes, frightening flashes.

At certain points of the movie, a scene would occur that was intended to be scary. But in order to really ratchet up the tension, a flash frame was inserted into the scene.

The demon known in the movie as Pazuzu was the one that was supposedly possessing the young girl Regan (Linda Blair). Although the demon never truly acted as a character of its own flesh in the movie, there were flash frames, or pictures of the demon that lasted about two-tenths of a second.

See an example of the video below with Regan's mother (Ellen Burstyn) in the kitchen.

In video terms, one second of video has approximately 30 frames. So the image of the demon would only last about 6 frames, which resulted in terming it as a "flash frame." This occurred on several occasions during the movie.

But the demon's face was one of pure terror. It was not some spiky horned monster with fangs but rather a ghoulish-looking entity with a pale face, brownish protruding human teeth, an exposed gum line and stressed redness around its eyes. The face was outlined in darkness, and in one flash frame, he appeared to be in pain. In another it appeared to be verging on a snarl. But the image was so quick that viewers saw it, and the image was etched into their brains while watching the marquee horror playing out in front of them.

This in essence intensified the horror of the scenes from an already "high" degree to a "dangerously high" degree.

See video of Father Damien Karras (Jason Miller) below in a dream sequence with the frame inserted.