Online research in philosophy

The study of preconscious versus conscious processing has an extensive history in cognitive psychology, dating back to the writings of William James. Much of the experimental work on this issue has focused on perception, conceived of as input analysis, and on the relation of consciousness to attentional processing. The present paper examines when input analysis becomes conscious from the perspectives of cognitive modelling, methodology, and a more detailed understanding of what is meant by "conscious processing." Current evidence suggests that perception becomes conscious at a late-arising stage of focal-attentive processing concerned with information integration and dissemination. Reliable criteria for determining when perception becomes conscious combine the evidence of "first-person," phenomenological reports with "third-person" functional dissociations between preconscious and conscious processing. There are three, distinct senses in which a process may be said to be "conscious." It might be "conscious" (a) in the sense that one is conscious of the process, (b) in the sense that the operation of the process is accompanied by consciousness (of its results) and (c) in the sense that consciousness enters into or causally influences the process. Consciousness of familiar stimuli, rather than entering into input analysis, appears to follow it, in human information processing. Processes closely associated with the appearance of consciousness such as information integration and dissemination appear to operate unconsciously. Consequently, perception appears to be "conscious" only in sense (b).

Conscious perception, like the sight of a coffee cup, seems to involve the brain identifying a stimulus. But conscious input activates more brain regions than are needed to identify coffee cups and faces. It spreads beyond sensory cortex to frontoparietal association areas, which do not serve stimulus identification as such. What is the role of those regions? Parietal cortex support the ‘first person perspective’ on the visual world, unconsciously framing the visual object stream. Some prefrontal areas select and interpret conscious events for executive control. Such functions can be viewed as properties of the subject, rather than the object, of experience – the ‘observing self’ that appears to be needed to maintain the conscious state.

In this paper I offer an explanation of the ineffability (linguistic inexpressibility) of sensory experiences. My explanation is put in terms of computational functionalism and standard externalist theories of representational content. As I will argue, many or most sensory experiences are representational states without constituent structure. This property determines both the representational function these states can serve and the information that can be extracted from them when they are processed. Sensory experiences can indicate the presence of certain external states of affairs but they cannot convey any more information about them than that. So, format- or code-conversion mechanisms that link different systems of representation (linguistic and perceptual) to each other will fail to extract any relevant information from sensory experiences that could be coded in language. They only way to establish specific roles for sensory experiences in communication and the organization of behavior is to attach to them, by associative links, words, or other behavioral responses. If a sensory experience has no linguistic label associated to it in a particular subject, then no linguistic description can token, or activate, that state in the subject. In other words, no linguistic description can cause a subject to undergo an unlabeled perceptual state. On the contrary, complex, or syntactically structured perceptual states can be built up, on the basis of descriptions, by mechanisms of constructive imagination (conceived here as one sort of format conversion). It is this difference between complex and unstructured representational states that gives us an understanding of the phenomenon we call the ineffability of qualia.

The so-called unity of consciousness consists in the compelling sense we have that all our conscious mental states belong to a single conscious subject. Elsewhere I have argued that a mental state's being conscious is a matter of our being conscious of that state by having a higher-order thought (HOT) about it. Contrary to what is sometimes argued, this HOT model affords a natural explanation of our sense that our conscious states all belong to a single conscious subject. HOTs often group states together, so that each HOT is about a cluster of target states; single HOTs represent qualitative states as spatially unified and intentional states as unified inferentially. More important, each HOT makes one conscious of oneself in a seemingly immediate way, encouraging a sense of unity across HOTs. And the same considerations that make us assume that our first-person thoughts all refer to the same self apply also to HOTs; becoming conscious of our HOTs in introspection thus leads to a sense that our conscious states are unified in a single self. I argue that neither essential-indexical reference to oneself nor the alleged immunity to error through misidentification conflicts with this account. I close by discussing the apparent connection of unity with free agency.

Edelman suggests that any shape is encoded by an excitation vector with components corresponding to excitations of corresponding neuronal modules. This results in discrimination of stimuli in a shape space of low dimensionality. Similar vector encoding is present in color vision. Red-green, blue-yellow, bright and dark neurons are modules that represent a number of different color stimuli in color space of low dimensionality. Vector encoding allows effective computation of color differences and color similarities. Such a neuronal vector-encoding approach has also been applied to the perception of visual movement, line orientation, and stereopsis.

We can perceive shapes visually and tactilely, and the information we gain about shapes through both sensory modalities is integrated smoothly into and functions in the same way in our behavior independently of whether we gain it by sight or touch. There seems to be no reason in principle we couldn't perceive shapes through other sensory modalities as well, although as a matter of fact we do not. While we can identify shapes through other sensory modalities—e.g., I may know by smell (the scent of mango) that the object causing my sensory experience is round—this is not perceiving an object as shaped, but rather inferring from the character of one's sensory experience and collateral information that an object of a certain shape caused it. That it is possible to perceive shape by other modalities, however, is suggested by the case of bats and aquatic mammals like dolphins which navigate through their environment by a form of sonar. It is plausible that they have some form of auditory representation of space, and so of shape. These facts about shape perception raise important questions about the relation between those features of perceptual experience which are intrinsic to different sensory modalities and the nature of our perceptual representation of shapes, and, more generally, of the space within which we perceive shaped objects to be located. John Campbell's paper, "Molyneux's Problem" (see above), raises a number of interesting and important questions about the nature of our perception of shape properties, particularly the cross-modal nature of shape perception, and ties them to more general questions about the nature both of perceptual..

What we perceive is the product of an intrinsic process and not part of external physical reality. This notion is consistent with the philosophical position of transcendental idealism but also agrees with physiological findings on the thalamocortical system. -Frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in thalamocortical networks, thereby transiently forming assemblies of coherent oscillations under constraints of sensory input and prefrontal attentional mechanisms. Perception and conscious experience may be based on such assemblies and sensory input to thalamic nuclei plays merely a constraining role in their formation. In schizophrenia, the ability of sensory input to modulate self-organisation of thalamocortical activity may be generally reduced. If during arousal thalamocortical self-organisation is underconstrained by sensory input, then attentional mechanisms alone may determine the content of perception and hallucinations may arise.

When a mental state is conscious – in the sense that there is something it is like for the subject to have it – it instantiates a certain property F in virtue of which it is a conscious state. It is customary to suppose that F is the property of having sensory quality. The paper argues that this supposition is false. The first part of the paper discusses reasons for thinking that unconscious mental states can have a sensory quality, for example in cases of absent-minded perception. If unconscious mental states can have a sensory quality, then sensory quality is an insufficient condition for consciousness. The second part of the paper argues that there are even better reasons to think that sensory quality is an unnecessary condition for consciousness. The idea is that mental states can be conscious even when they lack sensory quality, for example, in the case of certain conscious propositional attitudes. In the third part of the paper, an alternative to the rejected supposition, drawn from the phenomenological tradition, is offered: that consciousness is a matter of implicit self-awareness, rather than of sensory quality. According to this alternative, a mental state is conscious when, and only when, it involves implicit self-awareness.

What we perceive is the product of an intrinsic process and not part of external physical reality. This notion is consistent with the philosophical position of transcendental idealism but also agrees with physiological findings on the thalamocortical system. -Frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in thalamocortical networks, thereby transiently forming assemblies of coherent oscillations under constraints of sensory input and prefrontal attentional mechanisms. Perception and conscious experience may be based on such assemblies and sensory input to thalamic nuclei plays merely a constraining role in their formation. In schizophrenia, the ability of sensory input to modulate self-organisation of thalamocortical activity may be generally reduced. If during arousal thalamocortical self-organisation is underconstrained by sensory input, then attentional mechanisms alone may determine the content of perception and hallucinations may arise.