Anne Treisman and Garry Gelade suggests that when perceiving a
stimulus, features are "registered early, automatically, and in
parallel, while objects are identified separately" and at a
later stage in processing. The theory has been one of the most
influential psychological models of human visual attention.
According to Treisman, the first stage of the feature
integration theory is the preattentive stage. Perception occurs
automatically, unconsciously, effortlessly, and early in the
perceptual process. During this stage, the object is analyzed
for details such as shape, color, orientation and movement, with
each aspect being processed in different areas of the brain. The
idea that features are automatically separated appears to be
counterintuitive; however, we are not aware of this process
because it occurs early in perceptual processing, before we
become conscious of the object. The second stage of the feature
integration theory is the focused attention stage, where the
individual features of an object comb