These findings also suggest 
that reversal can be explained 
in an entirely different way. 
When one does not know that a 
figure can be seen in more than 
one way, one tends to organize 
it on the basis of certain 
principles—–for instance, in 
favor of the central region of 
Rubin’s vase and faces as figure 
rather than ground or, in the 
case of the Necker cube, in 
favor of the depth organization 
in which the cube appears to be 
horizontal rather than tipped 
on an edge. These preferences 
were in fact manifested in our 
experiment. Of course, if no 
such lawful factors are 
operating, the initial 
organization might be based on 
chance factors, such as where 
in the figure the observer 
happens to be fixating or 
attending. Once that 
organization occurs, the naive 
observer may stick with it, 
there being no particular 
reason to alter it. After a long 
period of inspection, which is 
only likely to occur in 
experiments, the observer may 
become bored (satiated, in the 
psychological meaning of the 
word). Or the observer may 
begin to wonder why he or she 
is supposed to continue looking 
at it and begin to look for 
alternatives, which of course 
would change the equation. Or 
the observer’s attention may 
wander, thus interfering with 
the maintenance of the initial 
organization. Obviously, naive 
observers sometimes do achieve 
a reversal, or reversible figures 
would never have been 
discovered.