Theories and Foundational Questions 93the experience of perception is one of direct contact with
the world. In this way, representations get the outside inside
(Epstein, 1993).
According to constructivist theory, the perceptual world is
constructed or assembled from the raw material of sensory
input and stored knowledge. The process of construction has
been likened to inference or problem solving, and more re-
cently the process has been characterized as computational.
The representational framework serves as a superstructure
for support of this conception of the perceptual process. Pro-
ponents of the computational/representational approach (e.g.,
Fodor, 1983; Fodor & Pylyshyn, 1981) argue that the only
plausible story of perception is computational and that the
only plausible computational story must assume a representa-
tional system in which the computations are executed.
It seems undeniable that if a variant of the standard
constructivist/computational approach is adopted, the repre-
sentational framework is needed to allow the approach to
proceed smoothly. Any theory that postulates a process re-
sembling nondemonstrative inference (Gregory, 1970; Rock,
1983, 1997; or the Bayesian approaches, e.g., Hoffman, 1998;
Knill & Richards, 1996) or a process of representational trans-
formation (e.g., Marr, 1982) must postulate a representational
medium for the display of “premises” or the display of repre-
sentations, that is, the output of processes (algorithms) that
operate over mappings. No one has been more straightfor-
ward and exacting in promoting this approach than Marr in
hisVision.
In contrast, the theory of direct perception makes no use of
representations. Advocates of direct theory argue that the
flaws of representationalism are insurmountable. Some of
these flaws are logical, such as the familiar troubles with the
representational theory of mind, the philosophical progenitor
of the contemporary representational framework. As one ex-
ample, if direct perception were only of representations, how
do we come to know what external objects are like, or which
representations they resemble? By hypothesis, we can only
perceive representations, so that whenever we may think that
we are observing external objects to compare them with rep-
resentations or to discover their intrinsic nature, we are only
observing other representations. In general, it is difficult to
escape from the world of representations.
In addition to pointing to logical difficulties, proponents
of the theory of direct perception see no need to invoke
representations in the first place. According to the ecological
realists, representationalism is parasitic on constructivism. If
constructivism is accepted, then representationalism is com-
pelling; but if it is rejected, then representationalism is
unmotivated.
Gestalt theory developed before the age of self-conscious
representationalism. There is no explicit treatment of repre-
sentations in the writings of the Gestalt theorists. Neverthe-
less, we can infer that the Gestalt theorists would have sided
with the advocates of direct perception in this matter. Con-
siderations that support this inference emerge in the next two
sections.Representational TransformationAs a general rule, perceiving is automatic and seamless.
Compare, for instance, the effortlessness of seeing with the
trouble and toil of learning and reasoning. Although the char-
acterization is unlikely to be questioned as a description of
the experience of ordinary seeing, when we consider the
process that underlies perceiving, important differences
among theories emerge with respect to decomposability.
Ignoring theoretical nuances for the present, we find that con-
structivist theories, both cognitive and computational, hold
a common view, whereas Gestalt theory and the theory of
direct perception adopt a contrasting position.
The constructivist view is that the process of perception
may be decomposed into a series of operations whose func-
tion is to take the raw input to the sensory surface and by a
series of transformations generate a distally correlated repre-
sentation of the environment. The process of perception is a
process of representational transformation. The construc-
tivists are drawn to this position by an a priori belief that only
a model of representational transformation will be sufficient
as a description of the perceptual process. One form of em-
pirical support for this belief is found in the requirements of
successful algorithms for the attainment of the objectives of
perception, such as generating three-dimensional structure
from stereopsis. Evidence of the psychological reality of the
putative intermediate representations is provided by experi-
mental procedures that ostensibly segregate the component
representations.
Neither Gestalt theory nor the theory of direct perception
makes use of the model of representational transformation.
They do not agree that postulation of a sequential multistage
process is necessary, and they question the interpretation of
the experimental data. For Gestalt theory, the perceptual
process is a noncognitive, highly interactive process that
automatically settles into the best fitting state (Epstein &
Hatfield, 1994; Hatfield & Epstein, 1985). Any effort to parse
the process into intermediate states is arbitrary. On no ac-
count should such contrived states be assigned a role in the
causal story of perception. Proponents (e.g., Gibson, 1966,
1979; Turvey, Shaw, Reid, & Mace, 1981) of the theory of