Critical fusion frequency was measured in young subjects before and after smoking and drinking. The test light is directed to a round opaque plate, 40mm in diameter, which the subject views at a distance of 50cm in a semi-darkend room, the light-dark ratio being 1 : 1.
Nineteen subjects were investigated on the effect of cigarette smoking. Of these, an increases in frequency was noted in 10, a decrease in 3, and no alteration in 1.
The frequency returned to the normal level in about 10 minutes.
After drinking 35m1 of .90 proof whisky, 11 out of 16 subjects revealed a increase, 1 revealed a decrease, and 4 showed no alteration.
There is no definite relationship between the habit of smoking or drinking and the behavior of the changes in the frequency.
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