PURPOSE: To demonstrate visual latency.
DESCRIPTION: A meter stick is held by one person directly above the hands of a second person, the victim. When the meter stick is dropped, the victim closes its hands to catch the meter stick. The reaction time T of the victim can be calculated as T=SQRT(2S/g), where g is the acceleration of gravity and S is the distance the meter stick has fallen.
The experiment is then repeated with the room darkened. Typically the meter stick will fall considerably further, due to the longer reaction time in a darkened environment. The increased time, due to visual latency, can be determined by subtracting the reaction time in the light from that in the dark.
This is one reason for increased reaction time in night driving.
REFERENCES: (PIRA unknown.) See other demonstrations of visual latency and the Pulfrich phenomenon.
EQUIPMENT: Meter stick.
SETUP TIME: None.
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