FILMS TAKE IT ON THE CHIN AGAIN

You have seen it in everything from Westerns to mysteries to the Three Stooges to screwball comedies. Somebody takes a gun or a lamp or a pan or a whiskey bottle and smacks somebody else over the head with it, rendering him instantly unconscious.

There are many exceptions, of course, but usually the smackee is only out the length of time it takes for the smacker to accomplish the script assignment--robbing a safe, rifling a desk, tying the victim up. When Rachel Ward was accidentally knocked out in “Dead Men Don’t Wear Plaid,” Steve Martin had just enough time to realign her breasts.

When the smackees come to, seconds after their smackers are gone, they groan, rub the backs of their heads and stumble off toward their next scenes where, very often, they are slated to be conked again.

This cinematic device has been employed successfully thousands of times, and will be thousands more. Like lights going out, cars not starting and lipstick left on cigarettes, it is simply too convenient to be ignored. The Hollywood hills are crawling with screenwriters who, at this very minute, are probably moving their characters into position.

The problem for people who have trouble suspending their disbelief, or who fear that movies set examples, is that knocking folks unconscious isn’t quite that easy. Your chances of giving someone a harmless three-minute snooze by lowering a lamp on him are about as good as your being able to tell the color of a lady’s underwear by pretending to have X-ray-vision eyes.

According to Dr. Donald Becker, chief of neurosurgery at UCLA, it’s not what you hit a person with, or where, that affects his consciousness, but how hard and from what angle.

Becker says he doesn’t get caught up in the physiological discrepancies in movies. (“When I go to the movies, I move out of the neurological mode and suffer through with the same sort of fright everyone else is suffering,” he says.) But as he describes the dynamics of being knocked cold, it’s clear that most big-screen blows would not produce their big-screen consequences.

Consciousness is located in the brain stem in the deep center of the brain, Becker says. For a person to be rendered unconscious by a hit on the head, his brain would have to be accelerated in one direction or another far enough to move the brain stem as well.

“When the brain stem is moved but not seriously damaged, there is a temporary paralysis of the vital function (of the stem),” Becker says. “The motor system fails and the person’s legs buckle from underneath him.”

This is what happens to boxers who are toppled over by punches in the ring. They can be dazed, or unconscious, for 30 or 40 seconds and quickly reorient themselves from the concussion.

As hard as boxers hit, their gloves absorb much of the shock. For people struck with a gun or a bottle, the brain is the glove. Becker says that the brain, like a blob of Jell-O, will move as far as two inches inside the skull. If the blow is severe enough to cause that much movement, he says the person will not only be knocked out but will probably also stop breathing.

“Breathing is controlled by the brain stem,” he says. “With every head injury where there is loss of consciousness, there’s a period of time where there is a cessation of breathing. That is what usually causes death in accidents. . . . The brain suffers a second insult from the lack of oxygen.”

In movies, the most common knockout blow is the one least likely to accomplish the task. How many times have you seen a leading lady smash a vase over the top of a bad guy’s head and rescue her leading man? That’s OK. A good vase, or even one from K mart, will do it.

But according to Becker, if the blow is struck from directly overhead, there is little chance of a knockout because the brain’s downward movement won’t necessarily jolt the brain stem.

Skip this paragraph if you’re queasy, but Becker says he once treated an industrial accident victim who never lost consciousness after his head got caught in one of those compressors that crushes old car bodies. The man could not see to his left, Becker says, a relatively minor symptom considering that the top of his skull had been pushed halfway through his brain.

Most of the gun-butt KOs we see in movies come from glancing blows. In real life, they would hurt like hell, and they would probably spill a lot of blood (the scalp is well nourished). They might even break a blood vessel inside the skull that, without quick professional help, could be lethal a few hours later. But they probably wouldn’t jolt the brain stem enough to cause unconsciousness.

Another common knockout device used in movies is the karate chop to the back of the neck. You can knock a person out that way, Becker says, but only if the force of the chop moves the brain stem above. The more likely effect, he says, is damage to blood vessels and arteries, which could cause a stroke.

Whether or not a person loses consciousness from a head or neck blow--front or back, standing or sitting, in front of his girl or alone in an alley--there is probably some irreparable cellular damage, says Becker. Punch-drunk ex-boxers are the example.

Sam Spade. Philip Marlowe. Mike Hammer. These guys got hit so often, they charged 25 bucks a day plus expenses and thought they were stealing. Rocky Balboa didn’t have a brain left when he got into the ring with the Soviet superhuman in “Rocky IV,” which explains how he survived it (no brain stem). If someone endured as many forced naps as James Bond, he wouldn’t remember such simple names as M and Q and would be lucky if he could count to 007.

Although he doesn’t expect neurological verisimilitude in movies, Becker says the violence does get to him occasionally--most recently, while watching a scene in the ultra-phony “The Untouchables” where a man is hit hard enough in the head by a baseball bat to open Al Capone’s vault.

“That was a death blow,” Becker says, adamantly. “I wasn’t amused.”

Whether anybody was amused or not, it hasn’t hurt the box office. To date, “The Untouchables” has grossed $69 million.