Hill on phenomenal consciousness

I argue that it is at least open to a proponent of type materialism for phenomenal consciousness to accept Hill’s representational theory of experiential awareness of perceptual qualia.     

Unitary and dual models of phenomenal consciousness

There is almost unanimous consensus among the theorists of consciousness that the phenomenal character of a mental state cannot exist without consciousness. We argue for a reappraisal of this consensus. We distinguish two models of phenomenal consciousness: unitary and dual. Unitary model takes the production of a phenomenal quality and it’s becoming conscious to be one and the same thing. The dual model, which we advocate in this paper, distinguishes the process in which the phenomenal quality is formed from the process that makes this quality conscious. We put forward a conceptual, methodological, neuropsychological and neural argument for the dual model. These arguments are independent but provide mutual support to each other. Together, they strongly support the dual model of phenomenal consciousness and the concomitant idea of unconscious mental qualities. The dual view is thus, we submit, a hypothesis worthy of further probing and development.     

Binding and the phenomenal unity of consciousness.

The binding problem is frequently discussed in consciousness research. However, it is by no means clear what the problem is supposed to be and how exactly it relates to consciousness. In the present paper the nature of the binding problem is clarified by distinguishing between different formulations of the problem. Some of them make no mention of consciousness, whereas others are directly related to aspects of phenomenal experience. Certain formulations of the binding problem are closely connected to the classical philosophical problem of the unity of consciousness and the currently fashionable search for the neural correlates of consciousness. Nonetheless, only a part of the current empirical research on binding is directly relevant to the study of consciousness. The main message of the present paper is that the science of consciousness needs to establish a clear theoretical view of the relation between binding and consciousness and to encourage further empirical work that builds on such a theoretical foundation.     

A global workspace model for phenomenal and access consciousness

Both the global workspace theory and Block’s distinction between phenomenal and access consciousness, are central in the current debates about consciousness and the neural correlates of consciousness. In this article, a unifying global workspace model for phenomenal and access consciousness is proposed. In the model, recurrent neural interactions take place in distinct yet interacting access and phenomenal brain loops. The effectiveness of feedback signaling onto sensory cortical maps is emphasized for the neural correlates of phenomenal consciousness. Two forms of top-down attention, attention for perception and attention for access, play differential roles for phenomenal and access consciousness. The model is implemented in a neural network form, with the simulation of single and multiple visual object processing, and of the attentional blink.     

Identifying hallmarks of consciousness in non-mammalian species

Most early studies of consciousness have focused on human subjects. This is understandable, given that humans are capable of reporting accurately the events they experience through language or by way of other kinds of voluntary response. As researchers turn their attention to other animals, "accurate report" methodologies become increasingly difficult to apply. Alternative strategies for amassing evidence for consciousness in non-human species include searching for evolutionary homologies in anatomical substrates and measurement of physiological correlates of conscious states. In addition, creative means must be developed for eliciting behaviors consistent with consciousness. In this paper, we explore whether necessary conditions for consciousness can be established for species as disparate as birds and cephalopods. We conclude that a strong case can be made for avian species and that the case for cephalopods remains open. Nonetheless, a consistent effort should yield new means for interpreting animal behavior.     

The global workspace theory,the phenomenal concept strategy,and the distribution of consciousness

Peter Carruthers argues that the global workspace theory implies there are no facts of the matter about animal consciousness. The argument is easily extended to other cognitive theories of consciousness, posing a general problem for consciousness studies. But the argument proves too much, for it also implies that there are no facts of the matter about human consciousness. A key assumption is that scientific theories of consciousness must explain away the explanatory gap. I criticize this assumption and point to an alternative strategy for defending scientific theories of consciousness, one that better reflects the ongoing scientific practice. I argue there are introspectable inferential connections from phenomenal concepts to functional concepts that scientists can use to individuate the global workspace in terms of capacities that animals and humans share.     

Where experiences are: Dualist, physicalist, enactive and reflexive accounts of phenomenal consciousness

Dualists believe that experiences have neither location nor extension, while reductive and ‘non-reductive’ physicalists (biological naturalists) believe that experiences are really in the brain, producing an apparent impasse in current theories of mind. Enactive and reflexive models of perception try to resolve this impasse with a form of “externalism” that challenges the assumption that experiences must either be nowhere or in the brain. However, they are externalist in very different ways. Insofar as they locate experiences anywhere, enactive models locate conscious phenomenology in the dynamic interaction of organisms with the external world, and in some versions, they reduce conscious phenomenology to such interactions, in the hope that this will resolve the hard problem of consciousness. The reflexive model accepts that experiences of the world result from dynamic organism–environment interactions, but argues that such interactions are preconscious. While the resulting phenomenal world is a consequence of such interactions, it cannot be reduced to them. The reflexive model is externalist in its claim that this external phenomenal world, which we normally think of as the “physical world,” is literally outside the brain. Furthermore, there are no added conscious experiences of the external world inside the brain. In the present paper I present the case for the enactive and reflexive alternatives to more classical views and evaluate their consequences. I argue that, in closing the gap between the phenomenal world and what we normally think of as the physical world, the reflexive model resolves one facet of the hard problem of consciousness. Conversely, while enactive models have useful things to say about percept formation and representation, they fail to address the hard problem of consciousness.

Identifying neural correlates of consciousness: the state space approach

This article sketches an idealized strategy for the identification of neural correlates of consciousness. The proposed strategy is based on a state space approach originating from the analysis of dynamical systems. The article then focuses on one constituent of consciousness, phenomenal awareness. Several rudimentary requirements for the identification of neural correlates of phenomenal awareness are suggested. These requirements are related to empirical data on selective attention, on completely intrinsic selection and on globally unconscious states. As an example, neuroscientific findings on synchronized gamma activity are categorized according to these requirements.     

Same old, same old: the same-order representation theory of consciousness and the division of phenomenal labor

The same-order representation theory of consciousness holds that conscious mental states represent both the world and themselves. This complex representational structure is posited in part to avoid a powerful objection to the more traditional higher-order representation theory of consciousness. The objection contends that the higher-order theory fails to account for the intimate relationship that holds between conscious states and our awareness of them–the theory ‘divides the phenomenal labor’ in an illicit fashion. This ‘failure of intimacy’ is exposed by the possibility of misrepresentation by higher-order states. In this paper, I argue that despite appearances, the same-order theory fails to avoid the objection, and thus also has troubles with intimacy. A version of this paper was presented at the ‘Self-Representational Approaches to Consciousness’ conference, Center for Consciousness Studies, University of Arizona, March 18th–20th, 2005.     

Audiovisual phenomenal causality

We report three experiments in which visual or audiovisual displays depicted a surface (target) set into motion shortly after one or more events occurred. A visual motion was used as an initial event, followed directly either by the target motion or by one of three marker events: a collision sound, a blink of the target stimulus, or the blink together with the sound. The delay between the initial event and the onset of the target motion was varied systematically. The subjects had to rate the degree of perceived causality between these events. The results of the first experiment showed a systematic decline of causality judgments with an increasing time delay. Causality judgments increased when additional auditory or visual information marked the onset of the target motion. Visual blinks of the target and auditory clacks produced similar causality judgments. The second experiment tested several models of audiovisual causal processing by varying the position of the sound within the visual delay period. No systematic effect of the sound position occurred. The third experiment showed a subjective shortening of delays filled by a clack sound, as compared with unfilled delays. However, this shortening cannot fully explain the increased tolerance for delays containing the clack sound. Taken together, the results are consistent with the interpretation that the main source of the causality judgments in our experiments is the impression of a plausible unitary event and that perfect synchrony is not necessary in this case.     

Lines that induce phenomenal transparency

Three neighbouring opaque surfaces may appear split into two layers, one transparent and one opaque beneath, if an outline contour is drawn that encompasses two of them. The phenomenon was originally observed by Kanizsa [1955 Rivista di Psicologia 69 3-19; 1979 Organization in Vision: Essays on Gestalt Psychology (New York: Praeger)], for the case where an outline contour is drawn to encompass one of the two parts of a bicoloured figure and a portion of a background of lightest (or darkest) luminance. Preliminary observations revealed that the outline contour yields different effects: in addition to the stratification into layers described by Kanizsa, a second split, opposite in depth order, may occur when the outline contour is close in luminance to one of the three surfaces. An initial experiment was designed to investigate what conditions give rise to the two phenomenal transparencies: this led to the conclusion that an outline contour superimposed on an opaque surface causes this surface to emerge as a transparent layer when the luminances of the contour and the surface differ, in absolute value, by no more than 13.2 cd m(-2). We have named this phenomenon 'transparency of the intercepted surface', to distinguish it from the phenomenal transparency arising when the contour and surface are very different in luminance. When such a difference exists, the contour acts as a factor of surface definition and grouping: the portion of the homogeneous surface it bounds emerges as a fourth surface and groups with a nearby surface if there is one close in luminance. The transparency phenomena ('transparency of the contoured surface') perceived in this context conform to the constraints of Metelli's model, as demonstrated by a second experiment, designed to gather 'opacity' ratings of stimuli. The observer judgments conformed to the values predicted by Metelli's formula for perceived degree of transparency, alpha. The role of the outline contour in conveying figural and intensity information is discussed.     

Physicalism and phenomenal concepts

Frank Jackson’s famous Knowledge Argument moves from the premise that complete physical knowledge is not complete knowledge about experiences to the falsity of physicalism. In recent years, a consensus has emerged that the credibility of this and other well-known anti-physicalist arguments can be undermined by allowing that we possess a special category of concepts of experiences, phenomenal concepts, which are conceptually independent from physical/functional concepts. It is held by a large number of philosophers that since the conceptual independence of phenomenal concepts does not imply the metaphysical independence of phenomenal properties, physicalism is safe. This paper distinguishes between two versions of this novel physicalist strategy—Phenomenal Concept Strategy (PCS)—depending on how it cashes out “conceptual independence,” and argues that neither helps the physicalist cause. A dilemma for PCS arises: cashing out “conceptual independence” in a way compatible with physicalism requires abandoning some manifest phenomenological intuitions, and cashing it out in a way compatible with those intuitions requires dropping physicalism. The upshot is that contra Brian Loar and others, one cannot “have it both ways.”     

Apparent movement in phenomenal space

The spatial and temporal variables in Korte’s third law of apparent movement were studied in pictorial arrays in which size constancy could be expected to prevail. The thresholds for apparent movement were determined under conditions in which two squares appeared on a plane either with or without perspective information for depth. The results suggest that apparent movement varies with the perceived depth separation only if the size of the stimulus pair is congruent with contextual depth representations. The obtained psychophysical function relating thresholds for third-dimensional movement to pictorial depth scale supports the view that apparent movement preserves gradient-of-texture information.