Why A Brush With Death Triggers The Slow-Mo Effect

... after a little searching, David discovered something called SCAD diving. (SCAD stands for Suspended Catch Air Device.) It's like bungee jumping without the bungee. Imagine being dangled by a cable about 150 feet off the ground, facing up to the sky. Then, with a little metallic click, the cable is released and you plummet backward through the air, landing in a net (hopefully) about 3 seconds later.

SCAD diving was just what David needed — it was definitely terrifying. But he also needed a way to judge whether his subjects' brains really did go into turbo mode. So, he outfitted everybody with a small electronic device, called a perceptual chronometer, which is basically a clunky wristwatch. It flashes numbers just a little too fast to see. Under normal conditions — standing around on the ground, say — the numbers are just a blur. But David figured, if his subjects' brains were in turbo mode, they would be able to read the numbers.

The Time Blur

The falling experience was, just as David had hoped, enough to freak out all of his subjects. "We asked everyone how scary it was, on a scale from 1 to 10," he reports, "and everyone said 10." And all of the subjects reported a slow-motion effect while falling: they consistently over-estimated the time it took to fall. The numbers on the perceptual chronometer? They remained an unreadable blur.

"Turns out, when you're falling you don't actually see in slow motion. It's not equivalent to the way a slow-motion camera would work," David says. "It's something more interesting than that."

According to David, it's all about memory, not turbo perception. "Normally, our memories are like sieves," he says. "We're not writing down most of what's passing through our system." Think about walking down a crowded street: You see a lot of faces, street signs, all kinds of stimuli. Most of this, though, never becomes a part of your memory. But if a car suddenly swerves and heads straight for you, your memory shifts gears. Now it's writing down everything — every cloud, every piece of dirt, every little fleeting thought, anything that might be useful.

Because of this, David believes, you accumulate a tremendous amount of memory in an unusually short amount of time. The slow-motion effect may be your brain's way of making sense of all this extra information. "When you read that back out," David says, "the experience feels like it must have taken a very long time." But really, in a crisis situation, you're getting a peek into all the pictures and smells and thoughts that usually just pass through your brain and float away, forgotten forever.

via Why A Brush With Death Triggers The Slow-Mo Effect : NPR.