Abstract
In 26 healthy adults the threshold for appearance of flicker, S1, and ΔS, that is, the difference of S1 and the threshold for disappearance, S2, were measured by the method of electric flicker, and the data obtained were treated statistically.
1. Some significant nt practice effect was observed in experiments on beginners, so that it is advisable to have at least one session for practice in such measurements.
2. There was a high correlation between S1 and ΔS, and between S2 and its standard deviation (S. D.) or ΔS and its S. D.
3. A threshold load with a bicycle ergometer, at which ΔS just increased significantly at 5 percent level was determined. After exercise with a load 1.5 times as great as the threshold load, both Sl and ΔS increased remarkably, where no significant correlation could be found between ΔS and its S. D.
4. ΔS was found more sensitive to threshold loads than was S1, where stimulation with Röntgen rays, vestibular stimulation and exercise with a bicycle ergometer were used as threshold loads. It was concluded from these findings that ΔS is a more sensitive indicator than S1, while both of them may be. used equally well for measuring effects of heavier loads.
We are greatly indebted to Prof. K. Motokawa for his generous guidance and valuable suggestions.
