microfiche - dizzy

[tali122]

on the few occasions i have used a microfiche at a library i have felt extremely dizzy and disorientated - -why is this happening? - i cant find any info that associates microfiche useage causing these symptoms

[Clanad]

It's probable that the machine produces flickering that's not discernable normally, but produces a a symp tom known as flicker vertigo... similar to driving through a forest with the sunlight flashing rapidly through the trees. I have a friend that can be induced into a seizure from flicker vertigo...
Here's a description of the phenomena from an Army Aviator's site, since the vertigo can be induced from light shining through helicopter rotorblades:
"Much time and research has been devoted to the study of the Flicker Vertigo illusion. A light flickering at a rate between 4 and 20 cycles per second can produce unpleasant and dangerous reactions such as nausea, vomiting, pilot vertigo, and, on rare occasions, convulsions and/or unconsciousness. These reactions tend to be exaggerated by fatigue, frustration or boredom. During the day, especially while flying instruments, this can be caused by sunlight flickering through the rotor system or propellers. At night, it can be caused by an anticollision light reflecting off the clouds when in instrument meteorological conditions (IMC). If this phenomenon causes safe flight to be compromised try to eliminate the source of the flicker".