A miniature display device, recently available commercially, is
aimed at providing a portable, inexpensive means of visual information
communication. The display is head mounted in front of one eye with the
other eye's view of the environment unobstructed. Various visual phenomena
are associated with this design. The consequences of these phenomena
for visual safety, comfort, and efficiency of the user were evaluated:
(1) The monocular, partially occluded mode ofoperation interrupts
binocular vision. Presenting disparate images to each eye results in binocular
rivalry. Most observers can use the display comfortably in this
rivalrous mode. In many cases, it is easier to use the display in a peripheral
position, slightly above or below the line of sight, thus permitting normal
binocular vision of the environment. (2) As a head-mounted device, the
displayed image is perceived to move during head movements due to the
response of the vestibulo-ocular reflex. These movements affect the visibility
of small letters during active head rotations and sharp accelerations.
Adaptation is likely to reduce this perceived image motion. No evidence
for postural instability or motion sickness was noted as a result of these
conflicts between visual and vestibular inputs. (3) Small displacements of
the image are noted even without head motion, resulting from eye movements
and the virtual lack of display persistence. These movements are
noticed spontaneously by few observers and are unlikely to interfere with
the display use in most tasks.
|