But what about reports that 
some of the people tested did 
not perceive perspective 
representation appropriately--
specifically, that they did not 
perceive depth in pictures as 
we do--even if they did 
recognize the objects 
represented. If they did not, the 
presumption is that they have 
not had the opportunity to 
learn the conventions of depth 
representation. William Hudson 
conducted a study in South 
Africa that has become well 
known in this regard. His 
subjects were shown a picture 
containing outline images of a 
man holding a spear, an 
elephant on a hill, and an 
antelope on the same level as 
the man. The man and the 
antelope were both relatively 
large and in the foreground of 
the figure. The elephant was 
farther away than either the 
man or the antelope. However, 
the elephant was placed 
between the images of the man 
and the antelope.  While most 
of us would say that the spear 
was aimed at the antelope, the 
subjects in the experiment 
often said that the spear was 
aimed at the elephant.