Visual recognition involves storing and retrieving
memories. Neural activity, triggered by the eye, forms an
image in the brain's memory system that constitutes an
internal representation of the viewed object. When an
object is encountered again, it is matched with its internal
representation and thereby recognized. Controversy
surrounds the question of whether recognition is a parallel,
one-step process or a serial, step-by-step one.
Psychologists of the Gestalt school maintain that objects
are recognized as wholes in a parallel procedure: the
internal representation is matched with the retinal image in
a single operation. Other psychologists have proposed that
internal representation features are matched serially with
an object's features. Although some experiments show
that, as an object becomes familiar, its internal
representation becomes more holistic and the recognition
process correspondingly more parallel, the weight of
evidence seems to support the serial hypothesis, at least
for objects that are not notably simple and familiar.