Visual Sensitivities and Discriminations and Their Role in Aviation
Abstract
(1) Selective 'blindness' to approaching or receding motion in depth exists and seems to be not uncommon in normally-sighted individuals. (2) A perfectly camouflaged bar within a random dot pattern was rendered visible by moving dots within the bar and outside the bar with equal and opposite velocities. (3) Shape discrimination was compared for motion-defined and contrast-defined dotted rectangles. At high dot speeds and contrasts aspect ratio discrimination equal for the two kinds of rectangle and, at 2-3%, corresponded to a change of side length of only 24 arc sec. (4) Orientation discrimination and shape discrimination degrade more rapidly at short presentation durations for a motion-defined than for a contrast-defined target. (5) The findings in (2)-(4) above suggest that helicopter pilots may be at risk of making visual judgement errors in nap of the earth flight where some objects and ground features are seen by motion alone when contrast or speed is low or when inspection duration is brief. (6) We have developed a simple portable test for assessing visual ability to see and discriminate motion-defined form. (7) the motion-defined letter test was used on 25 patients with multiple sclerosis and 50 controls; 34/50 eyes of patients were abnormal even though visual acuity was normal. (8) Nonlinear systems analysis: We have developed a new mathematical approach to testing multi-neuron models in which individuals neurons are modelled as rectifiers. (9) We have developed a nondestructive zoom-FFT technique that allows spectra of EEG and other time series to be computed with the theoretical resolution.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 30, 1989
- Accession Number
- ADA219319
Entities
People
- David Regan
Organizations
- University of York