Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to (...) adaptive success. This target article critically examines this approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency. (shrink)

This paper addresses what we consider to be the most pressing challenge for the emerging science of consciousness: the measurement problem of consciousness. That is, by what methods can we determine the presence of and properties of consciousness? Most methods are currently developed through evaluation of the presence of consciousness in humans and here we argue that there are particular problems in application of these methods to nonhuman cases—what we call the indicator validity problem and the extrapolation problem. The first (...) is a problem with the application of indicators developed using the differences between conscious and unconscious processing in humans to the identification of other conscious vs. nonconscious organisms or systems. The second is a problem in extrapolating any indicators developed in humans or other organisms to artificial systems. However, while pressing ethical concerns add urgency to the attribution of consciousness and its attendant moral status to nonhuman animals and intelligent machines, we cannot wait for certainty and we advocate the use of a precautionary principle to avoid causing unintentional harm. We also intend that the considerations and limitations discussed in this paper can be used to further analyze and refine the methods of consciousness science with the hope that one day we may be able to solve the measurement problem of consciousness. (shrink)

If a brain is duplicated so that there are two brains in identical states, are there then two numerically distinct phenomenal experiences or only one? There are two, I argue, and given computationalism, this has implications for what it is to implement a computation. I then consider what happens when a computation is implemented in a system that either uses unreliable components or possesses varying degrees of parallelism. I show that in some of these cases there can be, in a (...) deep and intriguing sense, a fractional (non-integer) number of qualitatively identical phenomenal experiences. This, in turn, has implications for what lessons one should draw from neural replacement scenarios such as Chalmers. (shrink)

What psychological and philosophical significance should we attach to recent efforts at computer simulations of human cognitive capacities? In answering this question, I find it useful to distinguish what I will call "strong" AI from "weak" or "cautious" AI. According to weak AI, the principal value of the computer in the study of the mind is that it gives us a very powerful tool. For example, it enables us to formulate and test hypotheses in a more rigorous and precise fashion. (...) But according to strong AI, the computer is not merely a tool in the study of the mind; rather, the appropriately programmed computer really is a mind, in the sense that computers given the right programs can be literally said to. (shrink)

This paper presents Integrated Information Theory of consciousness 3.0, which incorporates several advances over previous formulations. IIT starts from phenomenological axioms: information says that each experience is specific a sh it is what it is by how it differs from alternative experiences; integration says that it is unified a sh irreducible to non-interdependent components; exclusion says that it has unique borders and a particular spatio-temporal grain. These axioms are formalized into postulates that prescribe how physical mechanisms, such as neurons or (...) logic gates, must be configured to generate experience. The postulates are used to define intrinsic information as “differences that make a difference‘ within a system, and integrated information as information specified by a whole that cannot be reduced to that specified by its parts. By applying the postulates both at the level of individual mechanisms and at the level of systems of mechanisms, IIT arrives at an identity: an experience is a maximally irreducible conceptual structure, and the set of elements that generates it constitutes a complex. According to IIT, a MICS specifies the quality of an experience and integrated information Φ Max its quantity. From the theory follow several results, including: a system of mechanisms may condense into a major complex and non-overlapping minor complexes; the concepts that specify the quality of an experience are always about the complex itself and relate only indirectly to the external environment; anatomical connectivity influences complexes and associated MICS; a complex can generate a MICS even if its elements are inactive; simple systems can be minimally conscious; complicated systems can be unconscious; there can be true “zombies‘ a sh unconscious feed-forward systems that are functionally equivalent to conscious complexes. (shrink)

Imagine that you and a duplicate of yourself are lying unconscious, next to each other, about to undergo a complete step-by-step exchange of bits of your bodies. It certainly seems that at no stage in this exchange of bits will you have thereby switched places with your duplicate. Yet it also seems that the end-result, with all the bits exchanged, will be essentially that of the two of you having switched places. Where will you awaken? I claim that one and (...) the same person possesses both bodies, occupies both places and will experience both awakenings, just as a person whose brain has been bisected must at once experience both of the unconnected fields of awareness, even though each of these will falsely appear to him as the entirety of his experience. I also claim that the more usual apparent boundaries of persons are as illusory as those in brain bisection; personal identity remains unchanged through any variation or multiplication of body or mind. In all conscious life there is only one person - I - whose existence depends merely on the presence of a quality that is inherent in all experience - its quality of being mine, the simple immediacy of it for whatever is having experience. One powerful argument for this is statistical: on the ordinary view of personhood it is an incredible coincidence for you (though not for others) that out of 200,000,000 sperm cells the very one required on each occasion for your future existence was first to the egg in each of the begettings of yourself and all your ancestors. The only view that does not make your existence incredible, and that is not therefore (from your perspective) an incredible view, is that any conscious being would necessarily have been you anyway. It is a consequence that self-interest should extend to all conscious organisms. (shrink)

Some authors argue that phenomenal unity can be grounded in the attentional structure of consciousness, which endows conscious states with at least a foreground and a background. Accordingly, the phenomenal character of part of a conscious state comprises a content aspect and a structural aspect. This view presents the concern that such a structure does not bring about phenomenal unity, but phenomenal segregation, since the background is separated from the foreground. I argue that attention can still lead to a form (...) of phenomenal unity that connects the foreground with the background. Experiencing oneself as controlling the focus of attention can, at least occasionally, bring about an experienced connection between the attentional foreground and the attentional background of a conscious experience. (shrink)

In Representation Reconsidered , William Ramsey suggests that the notion of structural representation is posited by classical theories of cognition, but not by the ‘newer accounts’ (e.g. connectionist modeling). I challenge the assertion about the newer accounts. I argue that the newer accounts also posit structural representations; in fact, the notion plays a key theoretical role in the current computational approaches in cognitive neuroscience. The argument rests on a close examination of computational work on the oculomotor system.

ABSTRACTThe seminal work of David Marr, popularized in his classic work Vision, continues to exert a major influence on both cognitive science and philosophy. The interpretation of his work also co...

Recent advances in philosophical thinking about consciousness, such as cognitive phenomenology and mereological analysis, provide a framework that facilitates using computational models to explore issues surrounding the nature of consciousness. Here we suggest that, in particular, studying the computational mechanisms of working memory and its cognitive control is highly likely to identify computational correlates of consciousness and thereby lead to a deeper understanding of the nature of consciousness. We describe our recent computational models of human working memory and propose that (...) three computational correlates of consciousness follow from the results of this work: itinerant attractor sequences, top-down gating, and very fast weight changes. Our current investigation is focused on evaluating whether these three correlates are sufficient to create more complex working memory models that encompass compositionality and basic causal inference. We conclude that computational models of working memory are likely to be a fruitful approach to advancing our understanding of consciousness in general and in determining the long-term potential for development of an artificial consciousness specifically. (shrink)

The growing literature on philosophical thought experiments has so far focused almost exclusively on the role of thought experiments in confirming or refuting philosophical hypotheses or theories. In this paper we draw attention to an additional and largely ignored role that thought experiments frequently play in our philosophical practice: some thought experiments do not merely serve as means for testing various philosophical hypotheses or theories, but also serve as facilitators for conceiving and articulating new ones. As we will put it, (...) they serve as ‘heuristics for theory discovery’. Our purpose in the paper is two-fold: to make a case that this additional role of thought experiments deserves the attention of philosophers interested in the methodology of philosophy; to sketch a tentative taxonomy of a number of distinct ways in which philosophical thought experiments can aid theory discovery, which can guide future research on this role of thought experiments. (shrink)

Some philosophers have conflated functionalism and computationalism. I reconstruct how this came about and uncover two assumptions that made the conflation possible. They are the assumptions that (i) psychological functional analyses are computational descriptions and (ii) everything may be described as performing computations. I argue that, if we want to improve our understanding of both the metaphysics of mental states and the functional relations between them, we should reject these assumptions.

Some philosophers have conflated functionalism and computationalism. I reconstruct how this came about and uncover two assumptions that made the conflation possible. They are the assumptions that (i) psychological functional analyses are computational descriptions and (ii) everything may be described as performing computations. I argue that, if we want to improve our understanding of both the metaphysics of mental states and the functional relations between them, we should reject these assumptions. # 2004 Elsevier Ltd. All rights reserved.

The paper aims at establishing that the premises of both the inductive and the multi‐premised versions of the sorites argument are not apparently acceptable and that, therefore, sorites‐type arguments do not constitute logical or conceptual paradoxes. Rather, it is suggested that such arguments are most properly and fruitfully described as skeptical challenges. A secondary goal of the paper is to focus attention to the unduly neglected inductive version of the argument.

Computation is central to the foundations of modern cognitive science, but its role is controversial. Questions about computation abound: What is it for a physical system to implement a computation? Is computation sufficient for thought? What is the role of computation in a theory of cognition? What is the relation between different sorts of computational theory, such as connectionism and symbolic computation? In this paper I develop a systematic framework that addresses all of these questions. Justifying the role of computation (...) requires analysis of implementation, the nexus between abstract computations and concrete physical systems. I give such an analysis, based on the idea that a system implements a computation if the causal structure of the system mirrors the formal structure of the computation. This account can be used to justify the central commitments of artificial intelligence and computational cognitive science: the thesis of computational sufficiency, which holds that the right kind of computational structure suffices for the possession of a mind, and the thesis of computational explanation, which holds that computation provides a general framework for the explanation of cognitive processes. The theses are consequences of the facts that (a) computation can specify general patterns of causal organization, and (b) mentality is an organizational invariant, rooted in such patterns. Along the way I answer various challenges to the computationalist position, such as those put forward by Searle. I close by advocating a kind of minimal computationalism, compatible with a very wide variety of empirical approaches to the mind. This allows computation to serve as a true foundation for cognitive science. (shrink)

Uncovering the neural basis of consciousness is a major challenge to neuroscience. In this Perspective, Tononi and colleagues describe the integrated information theory of consciousness and how it might be used to answer outstanding questions about the nature of consciousness.

The properties of Turing’s famous ‘universal machine’ has long sustained functionalist intuitions about the nature of cognition. Here, I show that there is a logical problem with standard functionalist arguments for multiple realizability. These arguments rely essentially on Turing’s powerful insights regarding computation. In addressing a possible reply to this criticism, I further argue that functionalism is not a useful approach for understanding what it is to have a mind. In particular, I show that the difficulties involved in distinguishing implementation (...) from function make multiple realizability claims untestable and uninformative. As a result, I conclude that the role of Turing machines in philosophy of mind needs to be reconsidered. (shrink)

According to the integrated information theory of consciousness, consciousness is a fundamental observer-independent property of physical systems, and the measure Phi of integrated information is identical to the quantity or level of consciousness. For this to be plausible, there should be no alternative formulae for Phi consistent with the axioms of IIT, and there should not be cases of F being ill-defined. This article presents three ways in which Phi, in its current formulation, fails to meet these standards, and discusses (...) how this problem might be addressed. (shrink)

The science of consciousness has made great strides by focusing on the behavioural and neuronal correlates of experience. However, while such correlates are important for progress to occur, they are not enough if we are to understand even basic facts, for example, why the cerebral cortex gives rise to consciousness but the cerebellum does not, though it has even more neurons and appears to be just as complicated. Moreover, correlates are of little help in many instances where we would like (...) to know if consciousness is present: patients with a few remaining islands of functioning cortex, preterm infants, non-mammalian species and machines that are rapidly outperforming people at driving, recognizing faces and objects, and answering difficult questions. To address these issues, we need not only more data but also a theory of consciousness a sh one that says what experience is and what type of physical systems can have it. Integrated information theory does so by starting from experience itself via five phenomenological axioms: intrinsic existence, composition, information, integration and exclusion. From these it derives five postulates about the properties required of physical mechanisms to support consciousness. The theory provides a principled account of both the quantity and the quality of an individual experience, and a calculus to evaluate whether or not a particular physical system is conscious and of what. Moreover, IIT can explain a range of clinical and laboratory findings, makes a number of testable predictions and extrapolates to a number of problematic conditions. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can occur in some very simple systems. Conversely, it predicts that feed-forward networks, even complex ones, are not conscious, nor are aggregates such as groups of individuals or heaps of sand. Also, in sharp contrast to widespread functionalist beliefs, IIT implies that digital computers, even if their behaviour were to be functionally equivalent to ours, and even if they were to run faithful simulations of the human brain, would experience next to nothing. (shrink)

Several theories of consciousness first described about a decade ago, including the conscious electromagnetic information (CEMI) field theory, claimed that the substrate of consciousness is the brain’s electromagnetic (EM) field. These theories were prompted by the observation, in many diverse systems, that synchronous neuronal firing, which generates coherent EM fields, was a strong correlate of attention, awareness, and consciousness. However, when these theories were first described there was no direct evidence that synchronous firing was actually functional, rather than an epiphenomenon (...) of brain function. Additionally, any EM field-based consciousness would be a ‘ghost in the machine’ unless the brain’s endogenous EM field is also able to influence neuron firing. Once again, when these theories were first described, there was only indirect evidence that the brain’s EM field influenced neuron firing patterns in the brain. In this paper I describe recent experimental evidence which demonstrate that synchronous neuronal firing does indeed have a functional role in the brain; and also that the brain’s endogenous EM field is involved in recruiting neurons to synchronously firing networks. The new data point to a new and unappreciated form of neural communication in the brain that is likely to have significance for all theories of consciousness. I describe an extension of the CEMI field theory that incorporates these recent experimental findings and integrates the theory with the ‘communication through coherence’ hypothesis. (shrink)