A model of the neuropsychology of anxiety is proposed. The model is based in the first instance upon an analysis of the behavioural effects of the antianxiety drugs in animals. From such psychopharmacologi-cal experiments the concept of a “behavioural inhibition system” has been developed. This system responds to novel stimuli or to those associated with punishment or nonreward by inhibiting ongoing behaviour and increasing arousal and attention to the environment. It is activity in the BIS that constitutes anxiety and that (...) is reduced by antianxiety drugs. The effects of the antianxiety drugs in the brain also suggest hypotheses concerning the neural substrate of anxiety. Although the benzodiazepines and barbiturates facilitate the effects of γ-aminobutyrate, this is insufficient to explain their highly specific behavioural effects. Because of similarities between the behavioural effects of certain lesions and those of the antianxiety drugs, it is proposed that these drugs reduce anxiety by impairing the functioning of a widespread neural system including the septo-hippocampal system, the Papez circuit, the prefrontal cortex, and ascending monoaminergic and cholinergic pathways which innervate these forebrain structures. Analysis of the functions of this system suggests that it acts as a comparator: it compares predicted to actual sensory events and activates the outputs of the BIS when there is a mismatch or when the predicted event is aversive. Suggestions are made as to the functions of particular pathways within this overall brain system. The resulting theory is applied to the symptoms and treatment of anxiety in man, its relations to depression, and the personality of individuals who are susceptible to anxiety or depression. (shrink)

Drawing on previous models of anxiety, intermediate memory, the positive symptoms of schizophrenia, and goal-directed behaviour, a neuropsychological hypothesis is proposed for the generation of the contents of consciousness. It is suggested that these correspond to the outputs of a comparator that, on a moment-by-moment basis, compares the current state of the organism's perceptual world with a predicted state. An outline is given of the information-processing functions of the comparator system and of the neural systems which mediate them. The hypothesis (...) appears to be able to account for a number of key features of the contents of consciousness. However, it is argued that neitherthis nor any existing comparable hypothesis is yet able to explain why the brain should generate conscious experience of any kind at all. (shrink)

[opening paragraph]: Imagine you are a scientist from Mars observing Gary Kasparov playing a tournament with a chess computer. Would you have any reason to postulate consciousness in one player, but not the other? What is consciousness? How does the body produce it, and what is it for? Most people do not realize that there is a problem here because our conscious experience is the thing we know best. We are all familiar with the colours, smells and scenes around us, (...) the pains and itches we feel and the thoughts that are in our heads. Our world consists of conscious experiences. By `conscious experience' I mean anything that you have an awareness of, absolutely anything. I do not mean anything recondite like your capacity to reflect upon your own experiences, something which one might suppose that only we as human beings have and animals do not. I mean the absolute basics, like feeling pain. (shrink)

The first claim in the target article was that there is as yet no transparent, causal account of the relations between consciousness and brain-and-behaviour. That claim remains firm. The second claim was that the contents of consciousness consist, psychologically, of the outputs of a comparator system; the third consisted of a description of the brain mechanisms proposed to instantiate the comparator. In order to defend these claims against criticism, it has been necessary to clarify the distinction between consciousness-as-such and the (...) contents of consciousness, to widen the description of the neural machinery instantiating the comparator system, and to clarify the relationship between the contents of consciousness in the here-and-now and episodic memory. (shrink)

As well as data indicating relationships (emphasised in the target article) (1) between dopaminergic transmission in the nucleus accumbens and positive incentive motivation, and (2) between dopaminergic transmission and extraversion, other data (not accounted for by the hypotheses developed in the target article) indicate relationships (3) between accumbens dopaminergic transmission and cognitive, especially perceptual, processes that are disrupted in schizophrenia, and (4) between dopaminergic transmission and psychoticism. The tension between relationships 1 + 2 and 3 + 4 is discussed and (...) a tentative resolution proposed. (shrink)

Cognitive deficits were produced in rats by different methods of damaging the brain: chronic ingestion of alcohol, causing widespread damage to diffuse cholinergic and aminergic projection systems; lesions (by local injection of the excitotoxins, ibotenate, quisqualate, and AMPA) of the nuclei of origin of the forebrain cholinergic projection system (FCPS), which innervates the neocortex and hippocampal formation; transient cerebral ischaemia, producing focal damage especially in the CA1 pyramidal cells of the dorsal hippocampus; and lesions (by local injection of the neurotoxin, (...) colchicine) of the granule cells of the dentate gyrus. Following chronic alcohol or lesions of the FCPS, transplants of cholinergically rich fetal brain tissue into the terminal areas (neocortex and/or hippocampus) restored performance almost to control levels, with a time course consistent with growth of the transplants and integration with host tissue; transplants of cholinergically poor fetal tissue (hippocampus) were without effect, as were transplants of cholinergically rich tissue into the region containing the nuclei of origin of the FCPS. Grafts of primary cells enriched in glia and cultured neuroblastoma cells into the terminal areas of the FCPS were equally effective, suggesting that there are multiple mechanisms by which neural transplants can restore cognitive function following diffuse cholinergic damage. In contrast, after ischaemia- or neurotoxin-induced damage to CA1 or dentate granule cells respectively, cholinergically rich fetal transplants into the damaged hippocampal formation were ineffective in restoring performance. After ischaemic damage, however, performance was restored by suspension grafts of CA1 cells but not by transplants containing CA3 pyramidal cells or granule cells; and after colchicine damage it was restored by solid grafts containing granule but not CA1 pyramidal cells. Furthermore, electrophysiological evidence has demonstrated functional, graft type-specific host-graft functional neuronal connectivity. Thus, restoration of cognitive function by neural transplants is possible after damage to either diffuse (cholinergic) or point-to-point (intrahippocampal) forebrain systems, but the transplant must be appropriate to the damage to be repaired. Because the different types of brain damage studied provide analogues of human alcoholic dementia, Alzheimer's disease, and heart attack, these results are encouraging with regard to the eventual application of neural transplant surgery to the treatment of cognitive deficits in humans. (shrink)

The use of neural transplantation to alleviate cognitive deficits is still in its infancy. We have an inadequate understanding of the deficits induced by different types of brain damage and their homologies in animal models against which to assess graft-induced recovery, and of the ways in which graft growth and function are influenced by factors within the host brain and the environment in which the host is operating. Further, use of fetal tissue may only be a transitory phase in the (...) search for appropriate donor sources. Nevertheless, findings from our laboratory and elsewhere have made a prima facie case for successful cognitive reconstruction by graft methods. (shrink)

How does conscious experience arise out of the functioning of the human brain? How is it related to the behaviour that it accompanies? How does the perceived world relate to the real world? Between them, these three questions constitute what is commonly known as the Hard Problem of consciousness. Despite vast knowledge of the relationship between brain and behaviour, and rapid advances in our knowledge of how brain activity correlates with conscious experience, the answers to all three questions remain controversial, (...) even mysterious. This important book analyses these core issues and reviews the evidence from both introspection and experiment. To many its conclusions will be surprising and even unsettling: * The entire perceived world is constructed by the brain. The relationship between the world we perceive and the underlying physical reality is not as close as we might think * Much of our behaviour is accomplished with little or no participation from conscious experience. * Our conscious experience of our behaviour lags the behaviour itself by around a fifth of a second - we become aware of what we do only after we have done it. * The lag in conscious experience applies also to the decision to act - we only become aware of our decisions after they have been formed. * The self is as much a creation of the brain as is the rest of the perceived world. Written by a leading scientist, this accessible and compelling analysis of how conscious experience relates to brain and behaviour will have major implications for our understanding of human nature. (shrink)

What makes conscious experiences necessary for in- formation processing or behaviour (no one knows)? Would it be easier first to divide consciousness into different levels (probably not)? Is consciousness tied to information processing or brain states (no one knows)? Would the target article's comparator be improved by adding a continuously adjusting feedback (probably not)?

In lieu of an abstract, here is a brief excerpt of the content:The Triumph Of SisyphusJeffrey GordonThe gods had condemned Sisyphus to ceaselessly rolling a rock to the top of the mountain, whence the stone would fall back of its own weight. They had thought with some reason that there is no more dreadful punishment than futile and hopeless labor.1The words are, of course, Albert Camus's. They were first published in 1942. Since then, this voice—at once lyrical and austere, personal (...) and oracular—and the ancient image he calls up in these lines have become permanent parts of our postmodern consciousness. Like all the images that capture and create the character of our age, Sisyphus is always there for each of us. In the intimate space of our imagination, we can turn to him at will, and with only the slightest effort, we will find him as before—solitary, weather beaten, resigned, without illusion. I want to make that effort now, not to disturb Sisyphus in his labors, nor to uproot him, surely, but to try to be precise about a matter which is, perhaps, fatally elusive of precision, to try to make explicit the significance of this figure whose implicit significance has haunted us now for over half a century. Let us turn to Sisyphus, then, as we might turn, one aimless afternoon, to some old photographs of a person close to us, perhaps even of ourselves, in the hope that we might find in them something we had missed, some expression or gesture that inadvertently reveals the essence of a life.But we must be silent now, for the figure is emerging. There is the hill, and it is morning, a slight chill in the soundless air. The landscape here is treeless, the land covered only with broken rock and scattered brush. A wide path of sterile earth has been cut in the thick brush of [End Page 183] the hill. And there, at the base of the hill, the rock—grey, mottled with holes, enormous. Slow, laborious breathing is audible. The rough hand comes into view, the flesh thick, sun-burnt, heavily veined. It finds a jut on the rock to grip. And now the weather-worn clothes, the thick trunk and powerful back. And here at last the face of Sisyphus—our own face, of course, or the face of one of our own personae, the eyes squinting against the sun, hair disheveled. He takes his hand from the rock and brings it to his side. Perhaps he is not quite ready yet, perhaps he needs a moment longer of rest. He stands motionless, eyes turning up. What is he gazing at? The summit of the hill, every square inch of which he has seen a million times before? What could he hope to discover there? Is it the cloudless sky that has his attention? Is he noting the progress of the sun? Does he seek in reflection on its course some inspiration for the renewal of his labor? He continues to stare without expression. We can afford to leave him for a moment.The legend abounds in perplexities, or at least this is true of that retelling of the myth that has made it so important to us. Camus calls Sisyphus "the absurd hero." This is, then, the best that we can hope to be, for our lives, too, according to Camus, are absurd. But why should we believe this? Surely it is ludicrously question-begging to conduct an imaginative exercise in which we strip a life of all that could possibly make it worthwhile, then appeal to this figment of ours as proof of the futility of human existence.If we are tempted to see in Sisyphus's eternal rock-rolling a revelation of the emptiness of our own labors, we should be easily dissuaded from this when we consider what little alteration is required to transform this myth from the perfect image of meaninglessness to a perfectly serviceable conception of a meaningful life.2 All we need is to introduce some point, some minimal, common, everyday point to his labors, such as any one of our lives abounds in, and the transformation is accomplished. Assume, then, that Sisyphus rolls... (shrink)

Because consciousness has an organizational, or functional, center, Gray supposes that there must be a corresponding physical center in the brain. He proposes further that since this center generates consciousness, ablating it would eliminate consciousness, while leaving behavior intact. But the center of consciousness is simply the product of the functional linkages among sensory input, memory, inner speech, and so on, and behavior.

This Editorial reports an exchange in form of a comment and reply on the article “History and Nature of the Jeffreys–Lindley Paradox” (Arch Hist Exact Sci 77:25, 2023) by Eric-Jan Wagenmakers and Alexander Ly.

Lewis sender‐receiver games illustrate how a meaningful term language might evolve from initially meaningless random signals (Lewis 1969; Skyrms 2006). Here we consider how a meaningful language with a primitive grammar might evolve in a somewhat more subtle sort of game. The evolution of such a language involves the co‐evolution of partitions of the physical world into what may seem, at least from the perspective of someone using the language, to correspond to canonical natural kinds. While the evolved language may (...) allow for the sort of precise representation that is required for successful coordinated action and prediction, the apparent natural kinds reflected in its structure may be purely conventional. This has both positive and negative implications for the limits of naturalized metaphysics. (shrink)

David Lewis (1969) introduced sender-receiver games as a way of investigating how meaningful language might evolve from initially random signals. In this report I investigate the conditions under which Lewis signaling games evolve to perfect signaling systems under various learning dynamics. While the 2-state/2- term Lewis signaling game with basic urn learning always approaches a signaling system, I will show that with more than two states suboptimal pooling equilibria can evolve. Inhomogeneous state distributions increase the likelihood of pooling equilibria, but (...) learning strategies with negative reinforcement or certain sorts of mutation can decrease the likelihood of, and even eliminate, pooling equilibria. Both Moran and APR learning strategies (Bereby-Meyer and Erev 1998) are shown to promote successful convergence to signaling systems. A model is presented that illustrates how a language that codes state-act pairs in an order-based grammar might evolve in the context of a Lewis signaling game. The terms, grammar, and the corresponding partitions of the state space co-evolve to generate a language whose structure appears to reflect canonical natural kinds. The evolution of these apparent natural kinds, however, is entirely in service of the rewards that accompany successful distinctions between the sender and receiver. Any metaphysics grounded on the structure of a natural language that evolved in this way would track arbitrary, but pragmatically useful distinctions. (shrink)

Insofar as empirical inquiry involves the coevolution of descriptive language and theoretical commitments, a satisfactory model of empirical knowledge should describe the coordinated evolution of both language and theory. But since we do not know what conceptual resources we might need to express our future theories or to provide our best future faithful descriptions of the world, we do not now know even what the space of future descriptive options might be. One strategy for addressing this shifting-resource problem is to (...) track the predictive and linguistic dispositions of inquirers rather than to track their theories and conceptual resources directly. Sender-predictor games, a variant of Skyrms–Lewis sender-receiver games, provide very simple models for the coordinated coevolution of predictive and linguistic dispositions. Such models explain how it is possible for (1) predictive and descriptive dispositions of inquirers to coevolve, (2) term-wise incommensurable, but nevertheless descriptively faithful languages, to sequentially evolve, and (3) a sort of underdetermination to occur where inquirers might satisfy their descriptive and predictive aims by revising their linguistic dispositions, their theoretical dispositions, or both. Such models also provide an elementary characterization of what it might mean for descriptions of the world to be faithful and hence for empirical inquiry to be successful. In doing so they provide a relatively weak, but perfectly clear, endogenous account of epistemic norms. (shrink)

We consider two ways one might use algorithmic randomness to characterize a probabilistic law. The first is a generative chance* law. Such laws involve a nonstandard notion of chance. The second is a probabilistic* constraining law. Such laws impose relative frequency and randomness constraints that every physically possible world must satisfy. While each notion has virtues, we argue that the latter has advantages over the former. It supports a unified governing account of non-Humean laws and provides independently motivated solutions to (...) issues in the Humean best-system account. On both notions, we have a much tighter connection between probabilistic laws and their corresponding sets of possible worlds. Certain histories permitted by traditional probabilistic laws are ruled out as physically impossible. As a result, such laws avoid one variety of empirical underdetermination, but the approach reveals other varieties of underdetermination that are typically overlooked. (shrink)

Hugh Everett III proposed his relative-state formulation of pure wave mechanics as a solution to the quantum measurement problem. He sought to address the theory’s determinate record and probability problems by showing that, while counterintuitive, pure wave mechanics was nevertheless empirically faithful and hence empirical acceptable. We will consider what Everett meant by empirical faithfulness. The suggestion will be that empirical faithfulness is well understood as a weak variety of empirical adequacy. The thought is that the very idea of empirical (...) adequacy might be renegotiated in the context of a new physical theory given the theory’s other virtues. Everett’s argument for pure wave mechanics provides a concrete example of such a renegotiation. (shrink)

Mention of the name of Friedrich Schiller among both critics and defenders of Kant's moral philosophy has most often been with reference to the well known quip:“Gladly I serve my friends, but alas I do it with pleasure.Hence I am plagued with doubt that I am not a virtuous person.““Sure, your only resource is to try to despise them entirely,And then with aversion to do what your duty enjoins you.''This attention, however, has served to obscure the fact that Schiller truly (...) intended his remark as a joke, representing a serious, if understandable, misinterpretation of Kantian morality. Though Schiller's various attempts to articulate a theory of moral motivation include important divergences from Kant's account, they represent a response to a set of problems that arise in the context of Kantian moral theory. As such, they may be of greatest interest to moralists who are working within the Kantian tradition. In this paper, I clarify certain points of Schiller's critique of Kant's account of moral motivation and place them in the context of his broader project of reconciling Kantianism and an ethics of virtue. (shrink)

There is a long tradition of trying to find a satisfactory interpretation of Everett's relative-state formulation of quantum mechanics. Albert and Loewer recently described two new ways of reading Everett: one we will call the single-mind theory and the other the many-minds theory. I will briefly describe these theories and present some of their merits and problems. Since both are no-collapse theories, a significant merit is that they can take advantage of certain properties of the linear dynamics, which Everett apparently (...) considered to be important, to constrain their statistical laws. (shrink)

A resolution of the quantum measurement problem would require one to explain how it is that we end up with determinate records at the end of our measurements. Metaphysical commitments typically do real work in such an explanation. Indeed, one should not be satisfied with one's metaphysical commitments unless one can provide some account of determinate measurement records. I will explain some of the problems in getting determinate records in relativistic quantum field theory and pay particular attention to the relationship (...) between the measurement problem and a generalized version of Malament's theorem. (shrink)

There has been a spate of books recently on the subject of consciousness. Relatively few of these, however, have taken a serious look at the philosophical issues surrounding the study of consciousness. Jeffrey Foss's book Science and the Riddle of Consciousness: A Solution is a welcome exception.

On Bohm's formulation of quantum mechanics particles always have determinate positions and follow continuous trajectories. Bohm's theory, however, requires a postulate that says that particles are initially distributed in a special way: particles are randomly distributed so that the probability of their positions being represented by a point in any regionR in configuration space is equal to the square of the wave-function integrated overR. If the distribution postulate were false, then the theory would generally fail to make the right statistical (...) predictions. Further, if it were false, then there would at least in principle be situations where a particle would approach an eigenstate of having one position but in fact always be somewhere very different. Indeed, we will see how this might happen even if the distribution postulate were true. This will help to show how loose the connection is between the wave-function and the positions of particles in Bohm's theory and what the precise role of the distribution postulate is. Finally, we will briefly consider two attempts to formulate a version of Bohm's theory without the distribution postulate. (shrink)