Given the early appearance of 
constancy, how can we explain 
the fact that some studies 
indicate that constancy 
perception increases with age? 
It could mean that constancy is 
approximated in an infant and 
becomes refined with age. Or it 
could mean that young 
children understand the 
instructions in an experiment 
less clearly or differently than 
adults do. They may be more 
aware than adults of the 
conflict between the two modes 
of perception or, alternatively, 
adults may be clearer that the 
constancy mode is the one to 
focus on.

    The best available evidence 
on size perception is that 
children of 5 or 6 years of age 
only show some partial failure 
of constancy at a considerable 
distance, beyond 50 feet. Since, 
as we shall see in Chapter 3, it 
is most probable that the cues 
to distance beyond that range 
are based primarily on the 
kinds of information artists 
make use of--perspective, 
shadows, and the like--the 
deficit in children, if any, may 
be attributed to lack of 
sensitivity to such cues rather 
than to an immature capacity to 
achieve constancy.