Perceptual Coherence : Hearing and Seeing

9
Auditory and Visual
Segmentation
Iheard Dr. Fritz Heider, the famous Gestalt psychologist, say,
“The job of psychologists is to pierce the veil of the obvious.”
The organization and segmentation of the auditory and visual worlds into
objects and sources is so obvious, so commonplace, and so effortless that
the problem of how this organization was accomplished went unnoticed
until the Gestalt psychologists made it central to visual perceptual theory.
But it still took another 80 years before the pioneering work of Bregman
(1990) made auditory figure-ground organization central to auditory perceptual
theory.
The essential problem for the visual system is to segment the retinal
mosaic composed of independent receptors into enclosed objects with
continuous surfaces. The outputs of the receptors can be grouped in an infinite
number of ways. We cannot simply argue that we organize it the way
it is, because we do not know how it is. We are restricted to the information
on the retina, the proximal information. From that, we construct our
best guess about the environment, the distal world. The proximal information
must provide at least a provisional representation of the distal environment;
otherwise useful perception would not occur at all. But there are
ambiguities that must be resolved. The continuous surfaces often are partially
covered by other surfaces, so that the reflected light reaching the
observer consists of fragments of varying shapes and sizes that must be assigned
to objects. Moreover, we cannot perceive the entire perceptual field
at once. The objects have to be constructed by shifting attention to different
regions and then knitting the fragments together. This is simply the
aperture and correspondence problem posed once again. The aperture is
determined by span of attention, while the correspondence problem is to
determine which fragments go with which other fragments.
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