Five aspects of visual change detection are reviewed. The first concerns the concept of change itself, in particular the ways it differs from the related notions of motion and difference. The second involves the various methodological approaches that have been developed to study change detection; it is shown that under a variety of conditions observers are often unable to see large changes directly in their field of view. Next, it is argued that this “change blindness” indicates that focused attention is (...) needed to detect change, and that this can help map out the nature of visual attention. The fourth aspect concerns how these results affect our understanding of visual perception—for example, the implication that a sparse, dynamic representation underlies much of our visual experience. Finally, a brief discussion is presented concerning the limits to our current understanding of change detection. (shrink)

Fodor has argued that observation is theory neutral, since the perceptual systems are modular, that is, they are domain‐specific, encapsulated, mandatory, fast, hard‐wired in the organism, and have a fixed neural architecture. Churchland attacks the theoretical neutrality of observation on the grounds that (a) the abundant top‐down pathways in the brain suggest the cognitive penetration of perception and (b) perceptual learning can change in the wiring of the perceptual systems. In this paper I introduce a distinction between sensation, perception, and (...) observation and I argue that although Churchland is right that observation involves top‐down processes, there is also a substantial amount of information in perception which is theory‐neutral. I argue that perceptual learning does not threaten the cognitive impenetrability of perception, and that the neuropsychological research does not provide evidence in favor of the top‐down character of perception. Finally, I discuss the possibility of an off‐line cognitive penetrability of perception. (shrink)

Philosophers have often argued that ascriptions of content are appropriate only to the personal level states of folk psychology. Against this, this paper defends the view that the familiar propositional attitudes and states defined over them are part of a larger set of cognitive proceses that do not make constitutive reference to concept possession. It does this by showing that states with nonconceptual content exist both in perceptual experience and in subpersonal information-processing systems. What makes these states content-involving is their (...) satisfaction of certain basic conditions deriving from a general account of representation-driven behaviour that is neutral on the question of concept possession. It is also argued that creatures can be in states with nonconceptual content even though they possess no conceptual abilities at all. (shrink)

Because the visual system cannot process all of the objects, colors, and features present in a visual scene, visual attention allows some visual stimuli to be selected and processed over others. Most research on visual attention has focused on spatial or location-based attention, in which the locations occupied by stimuli are selected for further processing. Recent research, however, has demonstrated the importance of objects in organizing (or segregating) visual scenes and guiding attentional selection. Because of the long history of spatial (...) attention research, theories of spatial attention are more mature than theories of other visual processes, such as object segregation and object attention. In the present paper, I outline a biased competition account of object segregation and attention, following similar accounts that have been developed for spatial attention (Desimone and Duncan, 1995). In my biased competition account, I seek to understand how some objects can be segregated and selected over other objects in a complex visual scene. Under this account, there are two sources of visual information that allow an object to be processed over other objects: bottom-up information carried by the physical stimulus and top-down information based on an observer's goals. I use the biased competition account to combine many diverse findings from the object segregation and attention literatures into a common framework. (shrink)

As John Casti wrote, "Finally, a book that really does explain consciousness." This groundbreaking work by Denmark's leading science writer draws on psychology, evolutionary biology, information theory, and other disciplines to argue its revolutionary point: that consciousness represents only an infinitesimal fraction of our ability to process information. Although we are unaware of it, our brains sift through and discard billions of pieces of data in order to allow us to understand the world around us. In fact, most of what (...) we call thought is actually the unconscious discarding of information. What our consciousness rejects constitutes the most valuable part of ourselves, the "Me" that the "I" draws on for most of our actions--fluent speech, riding a bicycle, anything involving expertise. No wonder that, in this age of information, so many of us feel empty and dissatisfied. As engaging as it is insightful, this important book encourages us to rely more on what our instincts and our senses tell us so that we can better appreciate the richness of human life. (shrink)

How can we disentangle the neural basis of phenomenal consciousness from the neural machinery of the cognitive access that underlies reports of phenomenal consciousness? We can see the problem in stark form if we ask how we could tell whether representations inside a Fodorian module are phenomenally conscious. The methodology would seem straightforward: find the neural natural kinds that are the basis of phenomenal consciousness in clear cases when subjects are completely confident and we have no reason to doubt their (...) authority, and look to see whether those neural natural kinds exist within Fodorian modules. But a puzzle arises: do we include the machinery underlying reportability within the neural natural kinds of the clear cases? If the answer is ‘Yes’, then there can be no phenomenally conscious representations in Fodorian modules. But how can we know if the answer is ‘Yes’? The suggested methodology requires an answer to the question it was supposed to answer! The paper argues for an abstract solution to the problem and exhibits a source of empirical data that is relevant, data that show that in a certain sense phenomenal consciousness overflows cognitive accessibility. The paper argues that we can find a neural realizer of this overflow if assume that the neural basis of phenomenal consciousness does not include the neural basis of cognitive accessibility and that this assumption is justified by the explanations it allows. (shrink)

Much as we would like to conceive empirical thought as rationally grounded in experience, pitfalls await anyone who tries to articulate this position, and ...

In this paper I argue for the cognitive impenetrability of perception by undermining the argument from reentrant pathways. To do that I will adduce psychological and neuropsychological evidence showing that (a) early vision processing is not affected by our knowledge about specific objects and events, and (b) that the role of the descending pathways is to enable the early-vision processing modules to participate in higher-level visual or cognitive functions. My thesis is that a part of observation, which I will call (...) perception, is bottom-up and theory neutral. As such, perception could play the role of common ground on which a naturalized epistemology can be built and relativism avoided. (shrink)

We discuss at some length evidence from the cognitive science suggesting that the representations of objects based on spatiotemporal information and featural information retrieved bottomup from a visual scene precede representations of objects that include conceptual information. We argue that a distinction can be drawn between representations with conceptual and nonconceptual content. The distinction is based on perceptual mechanisms that retrieve information in conceptually unmediated ways. The representational contents of the states induced by these mechanisms that are available to a (...) type of awareness called phenomenal awareness constitute the phenomenal content of experience. The phenomenal content of perception contains the existence of objects as separate things that persist in time and time, spatiotemporal information, and information regarding relative spatial relations, motion, surface properties, shape, size, orientation, color, and their functional properties. (shrink)

The paper argues that the reference of perceptual demonstratives is fixed in a causal nondescriptive way through the nonconceptual content of perception. That content consists first in spatiotemporal information establishing the existence of a separate persistent object retrieved from a visual scene by the perceptual object segmentation processes that open an object-file for that object. Nonconceptual content also consists in other transducable information, that is, information that is retrieved directly in a bottom-up way from the scene (motion, shape, etc). The (...) nonconceptual content of the mental states induced when one uses a perceptual demonstrative constitutes the mode of presentation of the perceptual demonstrative that individuates but does not identify the object of perceptual awareness and allows reference to it. On that account, perceptual demonstratives put us in a de re relationship with objects in the world through the non-conceptual information retrieved directly from the objects in the environment. (shrink)

Philosophers from Hume, Kant, and Wittgenstein to the recent realists and antirealists have sought to answer the question, What are concepts? This book provides a detailed, systematic, and accessible introduction to an original philosophical theory of concepts that Christopher Peacocke has developed in recent years to explain facts about the nature of thought, including its systematic character, its relations to truth and reference, and its normative dimension. Particular concepts are also treated within the general framework: perceptual concepts, logical concepts, and (...) the concept of belief are discussed in detail. The general theory is further applied in answering the question of how the ontology of concepts can be of use in classifying mental states, and in discussing the proper relation between philosophical and psychological theories of concepts. Finally, the theory of concepts is used to motivate a nonverificationist theory of the limits of intelligible thought. Peacocke treats content as broad rather than narrow, and his account is nonreductive and non-Quinean. Yet Peacocke also argues for an interactive relationship between philosophical and psychological theories of concepts, and he plots many connections with work in cognitive psychology. (shrink)

A further development of Tye's theory of phenomenal consciousness along with replies to common objections.

Active externalism (also known as the extended mind hypothesis) says that we use objects and situations in the world as external memory stores that we consult as needs dictate. This gives us economies of storage: We do not need to remember that Bill has blue eyes and wavy hair if we can acquire this information by looking at Bill. I argue for a corollary to this position, which I call ‘internalism.’ Internalism says we can acquire knowledge on a need‐to‐know basis (...) by consulting portable, inner analogues of the world. This, however, leads to a dilemma. If the knowledge was stored in memory, it is difficult to see how we could have acquired it by consulting inner analogues, for it would seem that we knew it already. Moreover, if it was stored in memory, we lose the economies of storage that provide much of the rationale for external memory stores and hence for their inner analogues. If, on the other hand, the knowledge was not stored in memory, it is difficult to see how we could have acquired it by consulting inner analogues, for it was not there to be acquired. I propose a solution to this problem that turns on the concept of nonconceptual content, and I relate the solution to Stephen Kosslyn's (1994) architecture of perception and visual mental imagery. Viewed in a broader context, the solution shows that the world leaks into the mind, as well as mind leaking into the world. (shrink)

Conceptualist accounts of the representational content of perceptual experiences have it that a subject _S_ can experience no object, property, relation, etc., unless _S_ "i# possesses and "ii# exercises concepts for such object, property, or relation. Perceptual experiences, on such a view, represent the world in a way that is conceptual.

In "Things and Places," Zenon Pylyshyn argues that the process of incrementally constructing perceptual representations, solving the binding problem (determining which properties go together), and, more generally, grounding perceptual ...

How we see and how we visualize: why the scientific account differs from our experience.

In an earlier paper, "Non-conceptual Content and the 'Space of Reasons'", I distinguished two forms of the view that perceptual content is non-conceptual, which I called the 'state view' and the 'content view'. On the latter, but not the former, perceptual states have a different kind of content than do cognitive states. Many have found it puzzling why anyone would want to make this claim and, indeed, what it might mean. This paper attempts to address these questions.

I argue that, if content externalism is in tension with privileged access to content, then content externalism is also in tension with privileged access to phenomenal character. Content externalists may thus have a new problem on their hands. This is not because content externalism implies externalism about phenomenal character. My argument is compatible with the conviction that, unlike some propositional content, phenomenal character is not individuated by environmental factors. Rather, the argument involves considering in tandem two ideas which have become (...) prominent in the philosophy of mind concerning the introspection of phenomenal character. (shrink)

This long-awaited work by prominent Harvard psychologist Stephen Kosslyn integrates a twenty-year research program on the nature of high-level vision and mental ...

In Thomas Metzinger, Conscious Experience, Schoningh Verlag. 1995. [ online ].

In 1995, in my book, Ten Problems of Consciousness, I proposed a version of the theory of phenomenal consciousness now known as representationalism. The present book, in part, consists of a further development of that theory along with replies to common objections. It is also concerned with two prominent challenges for any reductive theory of consciousness: the explanatory gap and the knowledge argument. In addition, it connects representationalism with two more general issues: the nature of color and the location of (...) the phylogenetic dividing line between those creatures that are phenomenally conscious and those that are not. (shrink)

We discuss in some length evidence from the cognitive science suggesting that the representations of objects based on spatiotemporal information and featural information retrieved bottom‐up from a visual scene precede representations of objects that include conceptual information. We argue that a distinction can be drawn between representations with conceptual and nonconceptual content. The distinction is based on perceptual mechanisms that retrieve information in conceptually unmediated ways. The representational contents of the states induced by these mechanisms that are available to a (...) type of awareness called phenomenal awareness constitute the phenomenal content of experience. The phenomenal content of perception contains the existence of objects as separate things that persist in time and time, spatiotemporal information, and information regarding relative spatial relations, motion, surface properties, shape, size, orientation, color, and their functional properties. (shrink)

In this paper, we criticise the claim, made by J. McDowell and B. Brewer, that the contents of perceptual experience are purely conceptual.