Other investigators have had 
difficulty in utilizing Bower’s 
methods. Even if all of Bower’s 
findings were substantiated, 
however, they would not rule 
out the possibility that 
constancy is an achievement 
based on experience. Infants 
could develop constancy in the 
first several weeks of life. But 
with other methods, the 
presence of size constancy in 
very young infants, in fact 
even in newly born infants, 
has been confirmed. For 
example, recently Cad Granrud 
at Carnegie Mellon University, 
using a new method called 
habituation (to be described in 
Chapter 5), has shown that 
infants only a few days old 
perceive an object to be the 
same size when its distance and 
therefore its retinal-image size 
change, and tend not to 
perceive an object to be the 
same size when the size of its 
retinal image is maintained but 
the object’s size and distance 
are altered.

    Bower also performed 
experiments on constancy of 
shape in which the 
conditioned stimulus was a 
rectangle at a slant. The 
infants responded strongly 
when the rectangle was 
oriented to the frontal plane, 
suggesting that it looked much 
the same, but they responded 
only weakly to a trapezoidal 
shape in the frontal plane that 
generated the same retinal 
shape as the rectangle. These 
findings were confirmed by 
Australian investigators R. H. 
Day and B. E. McKenzie and by 
Alan Slater and Victoria 
Morison at the University of 
Exeter in England, who 
obtained evidence for shape 
constancy in newborn infants 
using the habituation method.