Visual Acuity under Vibration

Abstract

The influence of vertical sinusoidal vibration on the visual acuity of twelve human subjects, sitting restrained and without padding in an airplane seat mounted on a shake table, was investigated in the frequency range of 1 to 20 c/s. A. novel visual acuity tester was developed to achieve high accuracy of measurement and to obtain a great many observations in short time periods. The decrement of visual acuity normalized to a shake table acceleration of one g (vector) was determined. Maximum decrements occurred at those frequencies where resonances of the whole body and organ complexes had been determined by other methods. Below 12 c/s the decrements were due mainly to the physiological stress produced in the body and above 12 c/s to the image displacement on the retina which had more and more of a blurring effect. Measurements one minute after cessation of vibration indicated residual effects only at frequencies up to 12 c/s, peaks being at the same resonant frequencies.