When cognitive scientists apply computational theory to the
problem of phenomenal consciousness, as many have been doing
recently, there are two fundamentally distinct approaches available.
Consciousness is to be explained either in terms of the nature of
the representational vehicles the brain deploys or in terms of the
computational processes defined over these vehicles. We call versions
of these two approaches vehicle and process theories
of consciousness, respectively. However, although there may be space
for vehicle theories of consciousness in cognitive science, they are
relatively rare. This is because of the influence exerted, on the one
hand, by a large body of research that purports to show that the
explicit representation of information in the brain and conscious
experience are dissociable, and on the other, by the classical
computational theory of mind – the theory that takes
human cognition to be a species of symbol manipulation. Two
recent developments in cognitive science combine to suggest
that a reappraisal of this situation is in order. First, a number of
theorists have recently been highly critical of the experimental
methodologies used in the dissociation studies – so critical,
in fact, that it is no longer reasonable to assume that the
dissociability of conscious experience and explicit representation
has been adequately demonstrated. Second, classicism, as a theory
of human cognition, is no longer as dominant in cognitive science
as it once was. It now has a lively competitor in the form of
connectionism; and connectionism, unlike classicism, does have
the computational resources to support a robust vehicle theory
of consciousness. In this target article we develop and defend
this connectionist vehicle theory of consciousness. It takes the
form of the following simple empirical hypothesis: phenomenal
experience consists of the explicit representation of information in
neurally realized parallel distributed processing (PDP) networks.
This hypothesis leads us to reassess some common wisdom about
consciousness, but, we argue, in fruitful and ultimately plausible
ways.