Accession Number : ADA130231

Title :   Preliminay Investigation of Variation in Some Dark Adaptation Aspects fo Possible Relevance to Military Helicopter Aircrew.

Descriptive Note : Technical rept.,


Personal Author(s) : Donaldson,Eric

Full Text :

Report Date : Jun 1983

Pagination or Media Count : 91

Abstract : The variability in night visual capacity of military aircrew may be relevant to task selection especially for the low level night operation of the light observation helicopter. The experimental objective was to assess the extent of variation in threshold for spatial frequencies and in the time to recovery of dark adaptation after a standard light exposure simulating a flare illumination. The subjects were eleven volunteers, five of whom were aircrew. After assessment of their distant visual acuity, the subjects were dark adapted for a period of thirty minutes. The level of adaptation was measured with an adaptometer which had the capability of presenting the stimulus at several spatial frequencies. A brief exposure to the simulated flare illumination was immediately followed by assessment of the effect on dark adaptation and time for recovery. Considerable variation was demonstrated in the rate and threshold levels of dark adaptation for light and for resolution of several spatial frequencies. Following the simulated flare exposure of 0.8 mL for 90 seconds, most subjects attained a threshold level for light within 30 seconds and there was no evidence of a recovery effect in the curves of the threshold luminance for resolution of a 6.25 cycles per degree grating. Marked differences in the threshold levels and in the spread of the subjects' estimations were clearly evident.

Descriptors :   *Dark adaptation , Military personnel , Flight crews , Helicopters , Night vision , Visual acuity , Measurement , Threshold effects , Illumination , Light , Luminance

Subject Categories : Psychology
      Human Factors Engineering & Man Machine System

Distribution Statement : APPROVED FOR PUBLIC RELEASE