Illusion - Is Seeing Really Believing?/Illusion - Is Seeing Really Believing (1998)(Marshall Media)[Mac-PC].iso/mac/ILLUSION/SROCK_TX.CXT/00137_Text_res12t.txt

Text File | 1996-12-31 | 1KB | 49 lines

Oculomotor Cues
Accommodation of the lens
gives us cues to distance
through the varying blurriness
of objects.  But as represented
in this photograph,
accomodation loses its effect
beyond a few feet: objects at
differing distances will all be
in relatively sharp focus.

In principle, it should be easy
to determine if accommodation
alone is a cue to the perception
of depth. If you close one eye
and view a solitary, unfamiliar,
luminous object in a dark room
with your head held still, the
shape of the lens will
automatically adjust itself for
maximum sharpness of the
image, based on the objectΓÇÖs
distance. Such a method would
test the use of lens
accommodation as a cue to
absolute distance; the
information about distance
would have to derive ultimately
from the altered state of the
ciliary muscles in the eye that
governs the shape of the lens.
To test the value of lens
accommodation in gauging
relative distance or depth, we
need only add several more
objects, at varying distances, in
the same dark room. As the eye
accommodates for one objectΓÇÖs
distance, the images of the
other objects will be blurred;
the blurriness would
presumably serve as a cue that
those objects are not in the
same plane as the one fixated.
In this case, the information
would come from the
differential sharpness or blur
of several simultaneously
registered retinal images.