of the irregular figure and not of the circle. That is, theybelongto the irregular
form. With an effort, we can see them as part of a circle; then they belong to
the circle. In any mental representation of a drawing, a perceived line always
belongs to some figure of which it forms a part. The belongingness may shift,
for example, when we try to see the figure in a different way, but regardless of
howweseeit,itisalwaysapropertyofsomething.
There is a second principle that I want to introduce here because it has a
connection with the principle of belongingness. This is the principle of ‘‘exclu-
sive allocation.’’ It can be seen in an ambiguous visual figure such as the vase-
faces illusion of the Gestalt psychologists. An example is shown in figure 9.6.
We can interpret the figure as an outline of either a vase or two faces. The
‘‘exclusive allocation of evidence’’ describes how these interpretations affect the
line that separates the vase from a face. When we see the vase, that line is allo-
cated to the vase and defines its shape. When we see the face, the same line is
now allocated to the face. It is never allocated to both vase and face at the same
time, but exclusively to one of them.
The exclusive allocation principle says that a sensory element should not be
used in more than one description at a time. If the line is assigned to the vase,
thatassignment‘‘usesup’’thelinesothatitsshapecannotcontributetothe
shape of another figure at the same time. There are certain limits to this idea,
Figure 9.5
An example of ‘‘belongingness.’’ The dark portion of the line seems to belong to the irregular form.
Figure 9.6
An ambiguous drawing in which either a vase at the center or two faces at the sides can be seen.
222 Albert S. Bregman