Requirements
2. Requirements for the Analysis of Visual Stimulus
According to the author, the visual system and any other artificial imitating
the human visual system we may devise, must meet the following three criteria
(greater details regarding these criteria is provided in the following
sections):
-
Abstractness: ability to establish abstract properties and relations.
-
Open-endedness: ability to establish a large variety of properties and
relations including new ones.
-
Complexity: Ability to efficiently handle the complexity involved in determining
spatial relations e.g. scale independence.
2.1 Abstractness
Abstractness can be defined easily using an example (as done in the paper).
Consider a set of shapes S, satisfying some property P (for example, the
set of all shapes which are closed). Set S may be very large (as
in this example) and it may be impossible to determine whether some shape
B belongs to S by template matching (e.g. comparing each shape in S to
shape B). However, determining whether B belongs to S can be easily
tested by taking advantage of any regularities the set S
may contain. Regularities allow for membership testing in the set
S to be "broken down" into a set of operations which allow one to test
whether B is included in the set S quicker and more efficiently in comparison
to template matching. For example, given some polygon B, the human
system doesn't template match with every possible closed polygon.
Rather, other means are used. For example, if the shape is closed,
then placing some mark on the border of the shape, and tracing the boundary
of the shape, will eventually bring us back to the starting point only
if the shape is closed (this operation consists of marking and tracing,
which are described in greater detail in future sections).
Abstract Shape Properties refers to the establishment
of properties and relations of some large set by using any regularities
it may contain. According to the author, the human visual system
has this ability and it is performed by using a combination of processes
which in turn are composed of several basic "fundamental"
or "elemental" operations. The processes which
are comprised of these elemental operations are referred to as visual
Rroutines.
2.2 Open Endedness
The processes used to determine some property share the same elemental
operations e.g. the elemental operations are not created by some process
when it is need but rather, are available for any process to use.
The open-endedness requirement requires that these operations be combined
to perform new computations as required by the visual system.
2.3 Complexity
The elemental operations used by some process will be the same operation
and as mentioned above, are not created by some process when needed.
Furthermore, these elemental operations which may be operating on different
locations share some of their "resources". For example, there is
no independent module for each possible location in the visual field.
