Perceptual Coherence : Hearing and Seeing

376 Perceptual Coherence
For a first approximation, we can say that it is the cross-frequency correlations
for both hearing and seeing that generate the perception of structure,
and it is probably at this level that the correspondences between the two are
clearest. We can also understand the grouping in terms of redundancy reduction
(Barlow, 1981). Channels that are correlated can be combined,
leaving independent channels that maximize mutual information.
Contributions of the Gestalt Psychologists
As described in earlier chapters, the Gestalt psychologists embraced the
notion of psychophysical isomorphism. What we see is due to the operation
of field forces on the visual cortex, which organizes the sensory fragments
into continuous objects (see figure 9.1). The sensory fragments create attractive
and repulsive forces, and the field forces link fragments together
Figure 9.1. Every cortical point, if excited, generates an electrical field that diminishes
with distance (A). The particular stimulus configuration determines the polarity.
The proximal stimulus creates the excitation pattern and resulting field forces.
The field forces can combine to generate a larger unified field that determines the
organization (B). In this case, the stronger fields between nearer cortical units lead
to the perceptual grouping by rows (solid-line ellipses) instead of the alternate
grouping by columns (dotted-line ellipses).