Bas relief is the appearance of the cast metal,
the face of the hero or whatever it might be coming up at you.
When you look through the pseudoscope at a bas relief medal
that could be seen switching back and forth between bar relief and intaglio.
Intaglio is just the name for the opposite that the cast would be
appearing to go into the metals that are coming out toward you.
So ambiguous objects like that, like the bottom of a cup.
Many examples that he described in his writings on this between 1830 and
the 1850s, were indeed seeing in the way you might expect,
having confused the right and left eye view.
But for the most part, this is certainly true
from my experience looking through a pseudoscope the world looks pretty normal.
Well what does that mean?
It probably just means that stereoscopic vision and the monocular views of vision,
which of course are perfectly present when you look at the world with two eyes.
They're just in addition to the stereoscopic information you have or,
better put, the stereoscopic information is In addition to the major
contribution of all the monocular cues that we talked about.
What you see is a combination of those two things and
it's not just a switch generated by the pseudoscope.
So as in so many of these things,
it's more complicated than you might imagine.
But it was Wheatstone who put the foundation in place for
basically understanding stereoscopic vision as the different
eyes views just from the geometry of their position across the face,
the angle at which they look at near by objects.
And of course when they look at distant objects,
the stereoscopic effect goes down and you have to see it with bigger and
bigger objects because the eyes are more and more parallel.
And that should be obvious looking at a diagram such as the ones that we use to
show that the two eye views are different, like this.
This is remember our greeting distance, 30 centimeters so as you go further and
further distant in the objects that you are looking at they have to be bigger and
bigger separated by bigger and bigger distances in real world space
to generate some sensations during a scalpic depth at a distance.
But both things are contributing all the time to the distance.
And depth combination, that tells you how far away things are in the real world.
