The head-up display (HUD) was developed to provide the pilot simultaneous viewing of flight information and the outside environment. The HUD optics were collimated so that the symbols appear at opt...

Eye accommodation to head-up virtual images

The vestibulo-ocular reflex (VOR) stabilizes gaze to permit clear vision during head movements. It has been supposed that VOR function might be inferred from dynamic visual acuity (DVA), the acuity during imposed head motion. We sought to determine effectiveness of DVA for detection and lateralization of unilateral vestibulopathy, using rigorous psychophysical methods. Seventeen normal and 11 unilaterally vestibulopathic subjects underwent measurement of optically best corrected DVA during head motion. A variable size letter "E" 6 m distant was displayed in oblique random orientations to determine binocular DVA by a computer controlled, forced choice method. Three types of whole-body yaw rotation were delivered by a servo-controlled chair synchronized with optotype presentation. Two types of motion were predictable: (1) steady-state 2.0-Hz rotation at 10–130°/s peak velocity with repetitive optotype presentation only during head velocity exceeding 80% of peak; and (2) directionally predictable transients at peak accelerations of 1000, 1600 and 2800°/s2 with optotype presentation for 300 ms. For neither of these predictable motions did DVA in vestibulopathic subjects significantly differ from normal, with suggestions from search coil recordings that this was due to predictive slow and saccadic eye movements. Unilaterally vestibulopathic subjects experienced a significant decrease in DVA from the static condition during ipsilesional rotation for all three peak head accelerations. Only during directionally unpredictable transients with 75 ms or 300 ms optotype presentation was the sensitivity of DVA in unilaterally vestibulopathic subjects significantly abnormal during ipsilesional rotation. The ipsilesional decrease in DVA with head motion was greater for 75 ms than 300 ms optotype presentation. Search coil recordings confirmed hypometric compensatory eye movements during DVA testing with unpredictable, ipsilesional rotation. Receiver-operator characteristic analysis indicated ideal detection and lateralization of unilateral vestibulopathy by DVA tested with a 75-ms optotype exposure for unpredictable transient rotations to a peak acceleration of 2800°/s. DVA can reliably detect unilateral deafferentation only if precautions are taken to prevent compensation by predictive slow eye movements and saccades.

Dynamic visual acuity during transient and sinusoidal yaw rotation in normal and unilaterally vestibulopathic humans.

The roles of clinical and experimental optometry in the improvement of sports performance are considered in the light of existing research knowledge in vision and sport. A parallel is drawn between the manner in which the human performer uses vision to control skilled movement and the operation of a highspeed computer and a distinction is made between the reception and perception stages of visual information‐processing. It is suggested that the reception of visual information is largely limited by the physical characteristics of the visual system (‘hardware’) and a role for the clinical optometrist is proposed in terms of ensuring that adequate levels of visual ‘hardware’ exist for athletes. It is further suggested that enhancement of visual ‘hardware’ beyond normal levels is unlikely to improve sports performance substantially as perceptual performance appears to be primarily limited by the strategies (‘software’) performers have developed to mpe with the unique processing demands of their particular sports. Some examples of ‘software’ differences between expert and novice performers are provided and the effectiveness of altering perceptual strategies as a means of enhancing sports performance is considered. Copyright

Enhancing sports performance through clinical and experimental optometry

In initial 60-min sessions, the dynamic visual acuity (DVA) of 54 male college observers was determined over a range of target velocities (60, 90, 120, and 150 deg/s) at each of three durations (200, 400, and 600 ms). Following four 30-min practice sessions with the task, a final test session identical to the first was then conducted. Highly significant training effects on DVA were obtained; contrary to previous work, these effects were most marked for observers with initially poorer performance.

Training Effects on the Resolution of Moving Targets—Dynamic Visual Acuity

The purpose of this article is to illustrate the significance of the cognitive system in sport expertise. Consideration of visual-perceptual abilities, along with cognitive factors and their relationship with sport expertise, suggest that level of sport performance can be reliably differentiated on several cognitive dimensions. Information is given concerning the cognitive requirements of sports skills. It is argued that, although visual-perceptual abilities are inherent in all levels of sport performance, cognitive factors are essential for sport expertise.

Beals Rp

Papers

The relationship between basketball shooting performance and certain visual attributes.

The effects of ambient illumination and contrast on dynamic visual acuity.