If one looks at the 
illustration with the aid of a 
magnifying glass, one will see 
that the two patterns are almost 
identical. But there is a 
difference. The dots in the 
center of the right-hand 
pattern, inside the region of 
the "triangle," are shifted a bit 
to the left in relation to those 
in the left-hand pattern. On an 
almost microscopic scale, the 
necessary disparity between 
left and right is indeed present. 
The Julesz discovery shows, 
then, that the perceptual 
system can simultaneously 
process many minute 
differences between two 
retinal images and that in so 
doing it can construct an 
overall pattern or shape.