Time to pull out the knives and the hockey masks.

It's Halloween, so it won't be unusual to see Michael Myers, Freddy Krueger and Jason Voorhees roaming around. Slasher films are popular enough to be repeated endlessly on television and accepted enough that kids dress like their iconic villains for Halloween.

A sort of barometer for the nation's psyche, slasher films are one of the surer bets in film. "Saw V" opened last weekend, and it took in more than $30 million.

Even bad slasher films cash in. But why?

We like being scared, for starters. And we've been scared plenty in real life lately, with a long war, an economy in free-fall and a general sense of hopelessness as we lumber toward an election that has seemingly been contested forever. Daily stock reports are enough to send even the most jaded person screaming into the night.

And with Halloween here, it's the perfect time to watch someone whip out a knife or a chainsaw and set to work. It's convenient, no one really gets hurt, and it's cheaper than therapy.

"I can only tell you what a friend of mine told me some years ago in New York, before I was ever involved in 'Saw,' " says Tobin Bell, who plays Jigsaw, the catalyst for all the mayhem, in the films. "She wanted to go to a horror movie, and she went to these movies frequently. I said, 'What is it about these movies that attracts you?'

"She said, 'It's a visceral experience. It slams you back into your seat. You cannot intellectualize it.' It's almost like it's not just something that happens. You don't observe it from the outside. You actually participate in it on some level."

Whether that participation is limited to screaming and hiding your eyes or recognizing the genre as metaphor for life's scarier situations depends largely on the movie. And you don't necessarily have to have the latter, but you absolutely must have the former.

"The experience for audiences is that it is a visceral roller-coaster thrill ride that gets your adrenaline pumping," says Eric Red, who wrote screenplays for such films as "Near Dark," "The Hitcher" and "Body Parts." "The main thing to understand about the slasher genre is, it's not real. Real violence in realistic movies can be genuinely disturbing and upsetting. You have to separate the more scary reality of 'Psycho' from the heightened Freddy Krueger or 'Friday the 13th' movies, because the violence has a totally different effect. Slasher films are unreal, mostly."

And yet they help audiences deal with reality.

"Slasher films house metaphors for what our culture can't otherwise talk about — threats to the family, the shock of senseless violence, even the war on terror," says Robert Andrew Wilson, an English professor at Cedar Crest College in Allentown, Pa. "It's no coincidence that as the country began debating torture and the treatment of detainees at Guantanamo Bay, the 'Saw' series began with the tagline, 'How much blood would you shed to stay alive?' "

"The dramatic tradition of bloody spectacle is historical, on stage centuries before film," Red says. "Paris had the Grand Guignol Theatre, which was known for orchestrating gruesome and bloody death scenes on stage. And Shakespeare wrote 'Titus Andronicus,' which, let's face it, is basically a series of strung-together horror scenes. ...

"Perhaps slasher films are the modern-day version of Romans gathering at the coliseum to see Christians being thrown to lions. But nobody really gets hurt in a slasher film, except the filmmakers — by critics."