Saturday, February 28, 2009

Black Swans and Consciousness

Drive Magazine recently posted the chronology of a typical lab-based car crash-test, which I will reproduce here, noting that a millisecond is 1/1000th of a second, and that British people don't know how to spell:

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.

As Vaughan at Mind Hacks notes, the conscious awareness numbers are largely correct and are based on some famous EEG experiments done by Benjamin Libet.

No matter how well you train yourself to estimate probabilities and weigh the pros and cons of a decision, there are some situations that happen so fast as to be outside of conscious purview. This does not mean that "you" have no control, but your "conscious" module may not play any role.

If you want to make good decisions under extreme time pressure, you need to practice your preferred cognitive heuristics so thoroughly as to make them automatic.