We do not see the image covering F. 
Let us not be mistaken, however, that we do not see point F in the stereos- 
copic image, for the position of the mentally formed stereoscopic image is the 
psychical product of the retinal images and in the retinal images the point F was 
indeed covered. 
NO ra 
12 
So the figure b seems to us to be the exact solution. 
Summing up we may say: 
Stereoscopic vision is a function of normal binocular vision. 
Looking with two eyes normal binocular vision brings us to convergence and 
approximate accommodation beyond our will, as the object itself, by its rays 
touching our retinas, causes our mental reconstruction to be closely tied at the 
object sending the rays mentioned. 
However it is not true that each single eye only views a direction and that 
difference in distance is only appreciated when looking with both eyes. 
Looking with both eyes every point x that is nearer or further than our 
attention point F is mentally projected near the eye-axes, but keeps its normal 
distance. Bringing a complementary (stereoscopic) object on the same place 
where x appears, we get a three-dimensional combination. 
That combination appearing on our eye-axes at a place nearer to or further 
from our attention point F originates from a place in the median plane. As 
the point x is projected on the eye-axis at about the same distance as the 
point is actually lying, it will be clear that the distance of the combination 
is slightly changing, the more our eye-axes converge or diverge. 
  
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