Page 235 - Foundations of Cognitive Psychology : Core Readings

240 Albert S. Bregman

the breakdown of a physiological mechanism and the accomplishment of scene
analysis. This example illustrates how indirect the relation can be between
function and physiology.

Scene-Analysis View Prevents Missing of Vision-Audition Differences
It was argued in the earlier discussion that Gestalt explanations had to be sup-
plemented by ones based on scene analysis because the latter might lead us to
new phenomena, such as the role of the occluding mask in perceptual closure.
There is another difference between the two approaches. Because the Gestalt
theorists saw the principles of organization as following from general proper-
ties of neural tissue they focused on similarities between the senses rather than
on differences. The laws of grouping were stated in a general way, in terms of
adjectives (such as ‘‘proximity’’ or ‘‘similarity’’) that could apply equally well
to different sense modalities. This has had both useful and harmful effects. On
the positive side it has promoted the discovery of the similar way in which
perceptual organization works in different sense modalities. For example, the
similarities between apparent movement and auditory streaming have become
apparent. However, an exclusive focus on the common Gestalt principles,
neglecting the unique scene-analysis problems that each sense must solve, is
likely to neglect differences between them and cause us to miss some excellent
opportunities to study special problems in audition that make themselves evi-
dent once we consider the dissimilarities between the senses. The way to get at
them is to consider the differences in the way in which information about the
properties of the world that we care about are carried in sound and in light.
The fact that certain Gestalt principles actually are shared between the senses
could be thought of as existing because they are appropriate methods for scene
analysis in both domains.
As an example of the way that the scene-analysis approach can reveal im-
portant differences between the senses, let us go through the exercise of con-
sidering the roles of direct energy, reflected energy, and their mixture in the
two senses.

Differences in the Ecology of Vision and Audition
There is a crucial difference in the way that humans use acoustic and light
energy to obtain information about the world. This has to do with the dissim-
ilarities in the ecology of light and sound. In audition humans, unlike their rel-
atives the bats, make use primarily of the sound-emitting rather than the
sound-reflecting properties of things. They use their eyes to determine the
shape and size of a car on the road by the way in which its surfaces reflect
the light of the sun, but use their ears to determine the intensity of the crash by
receiving the energy that is emitted when this event occurs. The shape reflects
energy; the crash creates it. For humans, sound serves to supplement vision by
supplying information about the nature of events, defining the ‘‘energetics’’ of a
situation.
There is another difference that is very much related to this one: sounds
go around corners. Low-frequency sound bends around an obstruction while
higher frequency sound bounces around it. This makes it possible for us to