Perceptual Coherence : Hearing and Seeing

Basic Concepts 5
sources moving in three dimensions. It may be that the visual world consists
of light waves passing through transparent surfaces, or that the auditory
world consists of pressure waves reflecting off passive objects, but that
is not the usual way sensations arise and not the usual way we understand
and integrate those sensations. We make use of these usual properties to integrate
independent local excitations at the receptors (e.g., the motion of
lighted dots, the variation in sound pressure, the brightness patterning of
textures) into one or more coherent surfaces and objects. Visual information
is “shaped” by the object: the parallel beams of light from a distant
source (e.g., the sun) are reflected and shaped into a pattern that signifies
the surface and shape of the object. In similar fashion, auditory information
is shaped by the object: Air particles are mechanically “pushed around”
and shaped into a pattern that signifies the physical properties (e.g., shape,
size, material) of the vibrating surface.
Thus, I believe that the usual distinction that vision gives us objects and
audition gives us events is a trap. It misleads us into thinking about vision
as a spatial sense and about audition as a temporal sense. According to the
Oxford English Dictionary, the original definition of object is “something
thrown in the way,” or “to stand in the way so as to obstruct or obscure.”
Objects are typically opaque, so they block the recognition of other objects
that are behind them. In contrast, the definition of events is “to emerge out
of a temporal flow.” But all perceiving concerns the appearance of things,
and things exist in space and time simultaneously. To Griffiths and Warren
(2004), object analysis is the analysis of information that corresponds to
things and their separation from the rest of the sensory world. To put it
differently, all sensory input is interpreted in terms of familiar causative
agents or events and not in terms of the manner and nature of sensory stimulation
(R. M. Warren, 1999). Raymond (2000, p. 48) makes a similar
claim: “the idea is that the brain deals in the currency of object representations,
not disembodied stimulus features.”
One example of our inclination to perceive sensations as bound to objects
occurs with random dot kinematograms, as shown in figure 1.1. Dots are
programmed to move as if each were attached to the surface of a transparent
cylinder. Even though the cylinder is rotating at a constant speed (A), the
observer does not see the dots moving at a constant speed. Instead the observer
sees the dots slow down as they reach the edge of the cylinder, stop,
and then speed up in the reverse direction as they near the center line of the
cylinder (the dots also change size as they move from the front to the back
of the cylinder) (B). If the dots did not change velocity or size and simply
reversed direction, the perception would be that of a flat surface. Observers
effortlessly see the dots moving coherently, and attached to the front or back
surface of a rigid cylinder consistent with their direction of movement. What
is important is that the observers infer the presence of a cylinder even if