A second weakness of the 
theory is that the preferred 
perception does not always 
seem to support the theory’s 
predictions. In the case of 
interposition of unfamiliar, 
irregular shapes, like the 
circle and "rectangle" seen 
earlier, for example, the 
perception of depth seems no 
simpler than the perception of 
two shapes in the same plane, 
although we tend to perceive 
the former. Gaetano Kanizsa of 
the University of Trieste has 
also found examples of figures 
that seem to contradict the 
prediction of the simplicity-
preference theory.

    The simplicity-preference 
theory of depth perception is of 
course one in which depth is 
achieved on the basis of a built-
in predisposition of the 
nervous system rather than on 
past experience. Presumably, a 
brain that is so organized as to 
lead to simpler perceptual 
outcomes will have an 
evolutionary advantage. It is 
not clear, however, whether 
this is because of the economy 
of the encoding process or 
because whichever percept can 
be more efficiently encoded is 
more likely to represent what is 
actually there in the world. In 
any event, while this theory 
implies innate determination 
of perception, it is not the same 
as one that says that each 
particular pictorial cue is an 
innate sign of depth. In other 
words, what is innate 
according to this theory is the 
general tendency of mind to 
prefer perceptions that are 
simple rather than a tendency 
to interpret a specific pictorial 
cue as signifying depth.