Very recently Mary Peterson 
at the University of Arizona and 
her co-investigators have 
provided compelling evidence 
that past experience can 
influence figure-ground 
organization. Normally, as I 
have noted, figure-ground 
organization would occur first, 
in a bottom-up direction, since 
only then do specific shapes 
arise. Following that, the shape 
can be recognized (on the basis 
of similarity to a memory) if it 
is familiar. But Peterson’s 
research shows that great 
familiarity can seemingly 
determine that the familiar 
region in an ambiguous figure-
ground pattern will be 
perceived first and also 
determine that it will be 
perceived for a longer period of 
time as one continues to look at 
the pattern. In the illustration 
at left, subjects tended to see 
the half silhouette of a woman 
when the figure was presented, 
as you will probably also do. But 
when the figure was inverted, 
this did not occur, presumably 
because in that orientation the 
shape was not familiar. This 
leaves us with the problem of 
how the memory trace of a 
woman’s shape can affect the 
figure-ground organization, 
that is, with the problem of 
how that trace is selected 
before figure-ground 
organization first creates the 
shape to which the memory is 
then matched as similar.