SPECIAL PHASES 303are better than others, usually with the comparison based upon
resolving power. But the idea of one person being able to “do
things” with vision which others cannot is wholly strange.
In fact, it is just as possible to have skill with the eyes as with
the hands or body. Two people can look at a field of vision. One
person will see much more than the other. If they match colors,
one can do so far more accurately than another. If they look at a
tree, one can estimate the distance and height much more accur-
ately. And if both look at three posts in the distance set very
closely together, one will be able to say which is the nearest and
which the farthest, while the other may not be able even to guess
at the relative positions.
These are a few examples of visual skill. It is more largely sub-
jective than physical, in most instances. However, the point in
which we are interested is that although stereo reproduces the con-
ditions of direct vision, those who are accustomed to viewing
stereograms develop such visual skills more rapidly than do those
who see the same objects in reality. Just why the artificial stimulus
should produce greater skill seems to be in doubt, but the fact
itself has been too often demonstrated for there to be any doubt
whatsoever.
Stereo Suprernncy.-It is very easy to become highly enthusiastic
about stereo. Therefore the writer would like to point out that his
stereo experience is more than 30 years old, quite old enough for
the sharp edge of enthusiasm to be worn off. He should also like to
emphasize the point that the statements of stereo superiority
which have been made are not expressions of personal opinions,
but facts. They are facts which are subject to demonstration, facts
which are matters of record.