92 Foundations of Visual Perception
The view of the theory of direct perception concerning
information is radically different. Proponents of this theory
(Rogers, 2000) vigorously reject the assumption of in-
tractable equivocality. Following Gibson, they contend that
the tenet of equivocality is false, that it is mistakenly derived
from premises about the nature of the stimulation that enters
into the perceptual process. The cognitive constructivist who
mistakenly uses static displays of points or objects isolated
from their optical context (e.g., a point of light or an illumi-
nated object in the dark or a display presented briefly)
mistakenly concludes that stimulation is informationally im-
poverished. But direct perception argues that this paradigm
does not represent the optical environment that has shaped
the visual system. Even worse, the paradigm serves to create
experiments with informationally impoverished displays.
Thus equivocality is only an artifact of the constructivist’s
favored paradigm and not a characteristic of all optical stim-
ulation. The stimulation that the perceptual system typically
encounters and to which it has been attuned by evolution is
spatially and temporally distributed. These spatiotemporal
optical structures, which are configurations of optical motion,
canspecify the environment. There is sufficient information
in stimulation to support adaptive perception. And when
pickup of information suffices to explain perception, cogni-
tive operations that construct the perceptual world are super-
fluous.
The stance of the computational constructivist regarding
the question of information cannot be characterized easily. If
byinformationis meant a unique relationship between optical
input and a distal state that is unconditional and not con-
tingent on circumstances, then the computational construc-
tivist must be counted among the skeptics. Optical structures
cannot specify distal states noncontingently. Other conditions
must be satisfied. The other conditions, which may be called
constraints,are the regularities, covariances, and uniformities
of the environment. Accordingly, assertions about the infor-
mational status of optical stimulation must include two con-
joint claims: One is about properties of optical stimulation,
and the other is about properties of the environment.
Moreover, from a computational constructivist stance, still
more is needed to make information-talk coherent. Consider-
ation must be given to the processes and algorithms that make
explicit the relationships that are latent in the raw optical input.
Whereas the advocates of the theory of direct perception talk
of spatiotemporal optical structures, the computationalist sees
the structure as the product of processes that operate on un-
structured optical input. It is only in the tripartite context of
optical input, constraints, and processing algorithms that the
computationalist talks about information for perception.
The Gestalt psychologists, writing well before the forego-
ing theorists, also subscribed to the view that optical stimula-
tion does not carry information. Two considerations led them
to this conclusion. First, like the later computationalists, they
were convinced that it was a serious error to attribute organi-
zation or structure to raw optical input. The perceptual world
displays organization, and by Gestalt hypothesis the brain
processes underlying perception are organized; but retinal
stimulation is not organized. Second, even were it permissi-
ble to treat optical input as organized, little would be gained
because optical input underdetermines the distal state of
affairs. For example, even granting the status of an optical
motion configuration to an aggregate of points that displace
across the retina by different directions, amplitudes, and ve-
locities (i.e., granting organization to stimulation), there are
infinitely many three-dimensional structures consistent with
a given configuration of optical motion. For Gestalt theory,
structure and organization are the product of spontaneous dy-
namic interactions in the brain. Optical input is a source of
constraints in determining the solution into which the brain
process settles.Concerning RepresentationA representation is something that stands for something else.
To stand for a represented domain the representation does not
have to be a re-presentation. The representations that are
active in theoretical formulations of the perceptual process
are not iconic images of the represented domain. Rather, a
representation is taken to be a symbolic recoding that pre-
serves the information about objects and relations in the rep-
resented domain (Palmer, 1976).
Representations play a prominent role in cognitive and
computational constructivism. Positing representations is a
way of reconciling a sharp disparity between the phenome-
nology of everyday seeing and the scientific analysis of the
possibilities of seeing. The experience of ordinary seeing is
one of direct contact with the world. But as the argument
goes, even cursory analysis shows that all that is directly
available to the percipient is the light reflected from surfaces
in the world onto receptive surfaces of the eye. How can this
fundamental fact be reconciled with the nature of the expe-
rience of seeing? Moreover, how can the fact that only light
gets in be reconciled with the fact that it is the world that
we see, not light? (Indeed, what could it mean to say that we
see light?) Both questions are resolved by the introduction
of representations. It is representations that are experienced
directly, and because the representations preserve the fea-
tures, relationships, and events in the represented world,