APPARENT ROTATION OF A FIXED TARGET ASSOCIATED WITH LINEAR ACCELERATION IN FLIGHT.
NAVAL SCHOOL OF AVIATION MEDICINE PENSACOLA FLA
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The purpose of this study was to determine the effects of linear acceleration and deceleration on the visual perception of a target in the dark. Three subjects observed a collimated star in the dark while the pilot of an SNJ-6 aircraft executed various degrees of linear acceleration. When the subjects faced to the left in the aircraft the radiating lines of the star appeared to rotate about the central point to a new position. This rotation was clockwise during deceleration and counter clockwise during acceleration. As the force became smaller, the star appeared to rotate back to its normal position. This illusory rotation occurred at all stimulus levels. The thresholds of linear deceleration for motion and displacement were 0.067 G and 0.078 G respectively. All of the linear accelerations used were above threshold. The mean maximum rotation during deceleration increased as the decelerative force increased, the maximum estimated rotation reported being 15 degrees. There was also a positive relation between the maximum force and the duration of the illusory effect. The accelerative forces did not show a consistent variation with the maximum change in the accelerative force. The results are similar to those observed on a human centrifuge and show that linear acceleration and deceleration during flight have a marked influence upon visual perception in the dark. Author