February 19, 2009
Will you perceive the event that kills you?
David Eagleman in Sentient Developments:
One way to appreciate the slowness of your perception is to compare it to the speed of mechanical devices. Take this incredible, sobering "anatomy of a crash," as described in an Australian magazine and echoed on Tom Vanderbilt’s blog. With fine-grained temporal resolution, it analyzes what happens when a stationary Ford Falcon XT sedan is struck in the driver’s door by another vehicle traveling at 50 kilometers per hour:
0 milliseconds - An external object touches the driver’s door.
1 ms - The car’s door pressure sensor detects a pressure wave.
2 ms - An acceleration sensor in the C-pillar behind the rear door also detects a crash event.
2.5 ms - A sensor in the car’s centre detects crash vibrations.
5 ms - Car’s crash computer checks for insignificant crash events, such as a shopping trolley impact or incidental contact. It is still working out the severity of the crash. Door intrusion structure begins to absorb energy.
6.5 ms - Door pressure sensor registers peak pressures.
7 ms - Crash computer confirms a serious crash and calculates its actions.
8 ms - Computer sends a “fire” signal to side airbag. Meanwhile, B-pillar begins to crumple inwards and energy begins to transfer into cross-car load path beneath the occupant.
8.5 ms - Side airbag system fires.
15 ms - Roof begins to absorb part of the impact. Airbag bursts through seat foam and begins to fill.
17 ms - Cross-car load path and structure under rear seat reach maximum load.
Airbag covers occupant’s chest and begins to push the shoulder away from impact zone.
20 ms - Door and B-pillar begin to push on front seat. Airbag begins to push occupant’s chest away from the impact.
27 ms - Impact velocity has halved from 50 km/h to 23.5 km/h. A “pusher block” in the seat moves occupant’s pelvis away from impact zone. Airbag starts controlled deflation.
30 ms - The Falcon has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.
45 ms - Occupant and airbag move together with deforming side structure.
50 ms - Crash computer unlocks car’s doors. Passenger safety cell begins to rebound, pushing doors away from occupant.
70 ms - Airbag continues to deflate. Occupant moves back towards middle of car.
Engineers classify crash as “complete”.
150-300 ms - Occupant becomes aware of collision.
The last line is the zinger. Early studies by Benjamin Libet suggest that the last line should perhaps read as high as 500 ms, although others, such as Daniel Dennett, have correctly pointed out that it is impossible to measure the moment of onset of conscious experience, so the exact timing will never be known.
More here.
Posted by Abbas Raza at 04:37 AM | Permalink
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Dostoyevsky addressed a similar question in The Idiot, reflecting on capital punishment by guillotine.
"At last he began to mount the steps; his legs were tied, so that he had to take very small steps. The priest, who seemed to be a wise man, had stopped talking now, and only held the cross for the wretched fellow to kiss. At the foot of the ladder he had been pale enough; but when he set foot on the scaffold at the top, his face suddenly became the colour of paper, positively like white notepaper. His legs must have become suddenly feeble and helpless, and he felt a choking in his throat--you know the sudden feeling one has in moments of terrible fear, when one does not lose one's wits, but is absolutely powerless to move? If some dreadful thing were suddenly to happen; if a house were just about to fall on one;--don't you know how one would long to sit down and shut one's eyes and wait, and wait? Well, when this terrible feeling came over him, the priest quickly pressed the cross to his lips, without a word--a little silver cross it was- and he kept on pressing it to the man's lips every second. And whenever the cross touched his lips, the eyes would open for a moment, and the legs moved once, and he kissed the cross greedily, hurriedly--just as though he were anxious to catch hold of something in case of its being useful to him afterwards, though he could hardly have had any connected religious thoughts at the time. And so up to the very block.
"How strange that criminals seldom swoon at such a moment! On the contrary, the brain is especially active, and works incessantly-- probably hard, hard, hard--like an engine at full pressure. I imagine that various thoughts must beat loud and fast through his head--all unfinished ones, and strange, funny thoughts, very likely!--like this, for instance: 'That man is looking at me, and he has a wart on his forehead! and the executioner has burst one of his buttons, and the lowest one is all rusty!' And meanwhile he notices and remembers everything. There is one point that cannot be forgotten, round which everything else dances and turns about; and because of this point he cannot faint, and this lasts until the very final quarter of a second, when the wretched neck is on the block and the victim listens and waits and KNOWS-- that's the point, he KNOWS that he is just NOW about to die, and listens for the rasp of the iron over his head. If I lay there, I should certainly listen for that grating sound, and hear it, too! There would probably be but the tenth part of an instant left to hear it in, but one would certainly hear it. And imagine, some people declare that when the head flies off it is CONSCIOUS of having flown off! Just imagine what a thing to realize! Fancy if consciousness were to last for even five seconds!"
Brings a whole new meaning the the phrase "killed instantly" doesn't it?
Posted by: John Ballard | Feb 19, 2009 10:13:22 AM
"Curious the small and lesser fates that join to lead a man to this. The thousand brawls and stoven jaws, the clubbings and the broken bottles and the little knives that come from nowhere. For him perhaps it was all done in silence, or how would it sound, the shot that fired the bullet that lay already in his brain? These small enigmas of time and space and death."
Suttree, Cormac McCarthy
Posted by: Rob | Feb 19, 2009 12:58:21 PM
Frenchman Antoine-Laurent Lavoisier, considered the father of modern chemistry was arrested in 1794 for being a tax collector and quickly sentenced to death.
Ever the dedicated scientist, he requested time to complete some of his research so that it would be available to posterity, to that the presiding judge famously replied, “The republic has no needs for scientists.” The father of modern chemistry was promptly beheaded, his body tossed into a mass grave. He had reportedly instructed his assistant to count the number of words his severed head would attempt to mouth.
Now, that’s dedication to scientific ideals…
Posted by: Felix E F Larocca MD | Feb 19, 2009 8:15:49 PM
That delay until you realize the accident is kind of pointless as I think many people actually see the accident coming shortly before it happens. I certainly have in the ones I've been in. I had long enough to see what was coming, attempt to swerve (it was too close but I still tried), think "this is going to hurt" and then *wham* get knocked silly.
Posted by: Bonoro | Feb 20, 2009 12:41:02 AM
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