Gerard O'Brien

A connectionist theory of phenomenal experience

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.

Notes toward a structuralist theory of mental representation

Publisher Summary This chapter discusses that a structuralist theory of mental representation is “naturalistic” von Eckardt in the sense that it explains mental representation without appealing to properties that are nonphysical or antecedently representational. According to Barbara von Eckardt, convention is an inappropriate ground for mental representation as it violates the naturalism constraint. Resemblance is a fairly unconstrained relationship, because objects or systems of objects can resemble each other in a huge variety of ways and to various different degrees. However, one might hope to make some progress by starting with simple cases of resemblance, examining their possible significance for mental representation, and then turning to more complex cases. Two systems can share a pattern of relations without sharing the physical properties upon which those relations depend. Second-order resemblance is actually an abstract relationship. The crucial difference between a theory of mental representation based on structural resemblance and one based on physical resemblance is that the former is compatible with the implementation of mental representation in the brain.

How do connectionist networks compute

Although connectionism is advocated by its proponents as an alternative to the classical computational theory of mind, doubts persist about its computational credentials. Our aim is to dispel these doubts by explaining how connectionist networks compute. We first develop a generic account of computation—no easy task, because computation, like almost every other foundational concept in cognitive science, has resisted canonical definition. We opt for a characterisation that does justice to the explanatory role of computation in cognitive science. Next we examine what might be regarded as the “conventional” account of connectionist computation. We show why this account is inadequate and hence fosters the suspicion that connectionist networks are not genuinely computational. Lastly, we turn to the principal task of the paper: the development of a more robust portrait of connectionist computation. The basis of this portrait is an explanation of the representational capacities of connection weights, supported by an analysis of the weight configurations of a series of simulated neural networks.

Radical connectionism: thinking with (not in) language

Abstract In this paper we defend a position we call radical connectionism. Radical connectionism claims that cognition never implicates an internal symbolic medium, not even when natural language plays a part in our thought processes. On the face of it, such a position renders the human capacity for abstract thought quite mysterious. However, we argue that connectionism is committed to an analog conception of neural computation, and that representation of the abstract is no more problematic for a system of analog vehicles than for a symbol system. Natural language is therefore not required as a representational medium for abstract thought. Since natural language is arguably not a representational medium at all , but a conventionally governed scheme of communicative signals, we suggest that the role of internalised (i.e. self-directed) language is best conceived in terms of the coordination and control of cognitive activities within the brain.

Cognitive science and phenomenal consciousness: A dilemma, and how to avoid it

Abstract When it comes to applying computational theory to the problem of phenomenal consciousness, cognitive scientists appear to face a dilemma. The only strategy that seems to be available is one that explains consciousness in terms of special kinds of computational processes. But such theories, while they dominate the field, have counter‐intuitive consequences; in particular, they force one to accept that phenomenal experience is composed of information processing effects. For cognitive scientists, therefore, it seems to come down to a choice between a counter‐intuitive theory or no theory at all. We offer a way out of this dilemma. We argue that the computational theory of mind does not force cognitive scientists to explain consciousness in terms of computational processes, as there is an alternative strategy available: one that focuses on the representational vehicles that encode information in the brain. This alternative approach to consciousness allows us to do justice to the standard intuitions a...

The role of representation in computation

Reformers urge that representation no longer earns its explanatory keep in cognitive science, and that it is time to discard this troublesome concept. In contrast, we hold that without representation cognitive science is utterly bereft of tools for explaining natural intelligence. In order to defend the latter position, we focus on the explanatory role of representation in computation. We examine how the methods of digital and analog computation are used to model a relatively simple target system, and show that representation plays an in-eliminable explanatory role in both cases. We conclude that, to the extent that biologic systems engage in computation, representation is destined to play an explanatory role in cognitive science.

Dispensing With the Dynamic Unconscious

In recent years, a number of contemporary proponents of psychoanalysis have sought to derive support for their conjectures about the dynamic unconscious from the empirical evidence in favor of the cognitive unconscious. It is our contention, however, that far from supporting the dynamic unconscious, recent work in cognitive science suggests that the time has come to dispense with this concept altogether. In this paper we defend this claim in two ways. First, we argue that any attempt to shore up the dynamic unconscious with the cognitive unconscious is bound to fail, simply because the latter, as it is understood in contemporary cognitive science, is incompatible with the former as it is traditionally conceived by psychoanalytic theory. Second, we show how psychological phenomena traditionally cited as evidence for the operation of a dynamic unconscious can be accommodated more parsimoniously by other means.

Putting content into a vehicle theory of consciousness

The connectionist vehicle theory of phenomenal experience in the target article identifies consciousness with the brain’s explicit representation of information in the form of stable patterns of neural activity. Commentators raise concerns about both the conceptual and empirical adequacy of this proposal. On the former front they worry about our reliance on vehicles, on representation, on stable patterns of activity, and on our identity claim. On the latter front their concerns range from the general plausibility of a vehicle theory to our specific attempts to deal with the dissociation studies. We address these concerns, and then finish by considering whether the vehicle theory we have defended has a coherent story to tell about the active, unified subject to whom conscious experiences belong.

The Multiplicity of Consciousness and the Emergence of the Self

One of the most striking manifestations of schizophrenia is thought insertion. People suffering from this delusion believe they are not the author of thoughts which they nevertheless own as experiences. It seems that a person‘s sense of agency and their sense of the boundary between mind and world can come apart. Schizophrenia thus vividly demonstrates that self awareness is a complex construction of the brain. This point is widely appreciated. What is not so widely appreciated is how radically schizophrenia challenges our assumptions about the nature of the self. Most theorists endorse the traditional doctrine of the unity of consciousness, according to which a normal human brain generates a single consciousness at any instant in time. In this paper we argue that phenomenal consciousness at each instant is actually a multiplicity: an aggregate of phenomenal elements, each of which is the product of a distinct consciousnessmaking mechanism in the brain. We then consider how certain aspects of self might emerge from this manifold substrate, and speculate about the origin of thought insertion.

Disunity defended: A reply to Bayne

We have recently argued [8] that phenomenal consciousness is not a unity, in the sense of being a single thing at each instant. It is a multiplicity, an aggregate of phenomenal elements, each of which is the product of a distinct consciousness-making mechanism in the brain. We call this the multi-track conception of consciousness. It is, we believe, quite consistent with the available evidence, both phenomenologieal and neurophysiological, and ought to be considered a serious rival to more orthodox approaches. Tim Bayne, in a lively and stimulating paper [2], claims that our arguments in support of the multi-track conception are unpersuasive, and that the evidence we present is at best equivocal. We respond by defending our arguments on a number of fronts, and by taking a second look at the available evidence.