Observers inspected normal, high quality color displays of everyday visual scenes while their eye movements were recorded. A large display change occurred each time an eye blink occurred. Display changes could either involve "Central Interest" or "Marginal Interest" locations, as determined from descriptions obtained from independent judges in a prior pilot experiment. Visual salience, as determined by luminance, color, and position of the Central and Marginal interest changes were equalized. -/- The results obtained were very similar to those obtained in (...) prior experiments showing failure to detect changes occurring simultaneously with saccades, flicker, or “mudsplashes” in the visual scene: Many changes were very hard to detect, and Marginal Interest changes were harder to detect than Central Interest changes. -/- Analysis of eye movements showed, as expected, that the probability of detecting a change depended on the eye’s distance from the change location. However a surprising finding was that both for Central and Marginal Interest changes, evenwhen observers were directly fixating the change locations (within 1 degree),more than 40% of the time they still failed to see the changes. It seems that looking at something does not guarantee you “ see” it. (shrink)

When looking at a scene, observers feel that they see its entire structure in great detail and can immediately notice any changes in it. However, when brief blank fields are placed between alternating displays of an original and a modified scene, a striking failure of perception is induced: identification of changes becomes extremely difficult, even when changes are large and made repeatedly. Identification is much faster when a verbal cue is provided, showing that poor visibility is not the cause of (...) this difficulty. Identification is also faster for objects mentioned in brief verbal descriptions of the scene. These results support the idea that observers never form a complete, detailed representation of their surroundings. In addition, results also indicate that attention is required to perceive change, and that in the absence of localized motion signals it is guided on the basis of high-level interest. (shrink)

Computing Methodologies -- Artificial Intelligence.

This essay* takes two notions of autonomy and two notions of explanation and argues that colours occur in explanations that fall under all of them. The claim that colours can be used to explain anything at all may seem to some people an outrage. But their pessimism is unjustified and the orthodox dispositional view which may seem to support it, I shall argue, itself has difficulties. In broad terms, Section 2 shows that there exist good straight scientific laws of colour, (...) constituting what one might call a phenomenal science. Section 3 offers a larger view of what we are doing when we attribute colours to things, a view which makes it a case of holistic explanation, similar in many ways to psychological explanation. Section 2 emphasizes the model of scientific explanation, and Section 3 the holistic model found in rational explanation; but it will emerge that colour explanation in different ways fits both models, as it also does the two principal notions of autonomy that the first section identifies. (shrink)

Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of (...) acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The out- side world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the gov- erning laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Sev- eral lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual “filling in,” visual stability despite eye movements, change blindness, sensory substitution, and color perception. (shrink)

Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on (...) the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness. (shrink)

The book is an extended study of the problem of consciousness. After setting up the problem, I argue that reductive explanation of consciousness is impossible , and that if one takes consciousness seriously, one has to go beyond a strict materialist framework. In the second half of the book, I move toward a positive theory of consciousness with fundamental laws linking the physical and the experiential in a systematic way. Finally, I use the ideas and arguments developed earlier to defend (...) a form of strong artificial intelligence and to analyze some problems in the foundations of quantum mechanics. (shrink)

(1) The purported evidence for neural filling-in is not evidence for filling-in, but just for long-range dynamic interactions. (2) Vision is perhaps not an “illusion,” but at any rate it is not “pictorial.” (3) The idea of the “world as an outside memory” as well as MacKay's “conditional readiness for action” may help approach an “enactive” theory of vision.

In visual science the term filling-inis used in different ways, which often leads to confusion. This target article presents a taxonomy of perceptual completion phenomena to organize and clarify theoretical and empirical discussion. Examples of boundary completion (illusory contours) and featural completion (color, brightness, motion, texture, and depth) are examined, and single-cell studies relevant to filling-in are reviewed and assessed. Filling-in issues must be understood in relation to theoretical issues about neuralignoring an absencejumping to a conclusionanalytic isomorphismCartesian materialism, a particular (...) neural stage that forms the immediate substrate of perceptual experience enactiveanimatesubpersonal” considerations about internal processing, but rather by considerations about the task of vision at the level of the animal or person interacting with the world. (shrink)

unmittelbar wahr; sie ist zusammen, gleichzeitig mit uns und steht zu uns in der Beziehung des Gesehen-, Getastet-, Gehört werdens usw. Wirkliche Wahrnehmungen stehen dabei im Konnex mit Wahrnehmungsmöglichkeiten, mit vergegenwärti- 5 genden Anschauungen; in den Zusammenhängen der unmittel baren Wahrnehmung sind Leitfäden enthalten, die uns fortführen von Wahrnehmung zu Wahrnehmung, von einer ersten Um gebung zu immer neuen Umgebungen, und dabei trifft der wahr nehmende Blick die Dinge in der Ordnung der Räumlichkeit. Wir 10 haben auch eine zeitliche Umgebung, (...) eine nähere und fernere; eben gewesener Dinge und Vorgänge erinnern wir uns unmittel bar; sie waren nicht nur, sondern stehen jetzt in der Beziehung des Erinnertwerdens zu uns; worin auch beschlossen ist das Soeben-wahrgenommenworden-Sein. Die Erinnerung gleicht dabei 15 als fortgesetzte Wiedererinnerung einem Leitfaden; sie führt uns in der Zeit Schritt für Schritt zurück, und damit treten immer neue Linien der räumlich-zeitlichen Wirklichkeit, und zwar der vergangenen, zu uns in Beziehung, in diese eigentümliche Be ziehung der Erinnerung und des Wahrgenommenworden-Seins. 20 Die Zukunft der Welt tritt zu uns in Beziehung durch die voraus blickende Erwartung. über diesen niederen Akten bauen sich höhere auf, in denen wir uns denkend, schließend, theoretisierend zur Welt in Beziehung setzen; und wieder kommen dazu die sogenannten emotionalen Akte, in sich neue solche Be- 25 ziehungen konstituieren, obschon Beziehungen, die einer anderen Sphäre angehören. Wir schätzen als angenehm und unangenehm, als gut und schlecht, wir greifen handelnd in die Welt ein usw. (shrink)

If a man born blind were to gain his sight in later life would he be able to identify the objects he saw around him? Would he recognise a cube and a globe on the basis of his earlier tactile experiences alone? This was William Molyneux's famous question to John Locke and it was much discussed by English and French empiricists in the eighteenth century as part of the controversy over innatism and abstract ideas. Dr Morgan examines the whole history (...) of this debate: Locke's own (negative) answer to the question, the contributions of Berkeley, Condillac, Diderot and Voltaire and the factual accounts of early cataract operations and modern laboratory studies. He shows how this debate is involved in the development and eventual separation of philosophy and experimental psychology after the eighteenth century and considers why the original question is effectively still unanswered. This is one problem-area with its intricate cluster of connected conceptual and technical difficulties which suggests the need for some reunion or at least collaboration between the two subjects. (shrink)