Recent results showing that large changes in a scene are not noticed if they occur at the same time as a global visual disturbance caused by saccades, ﬂicker, "mudsplashes", or ﬁlm cuts, are generally explained in terms of a theory in which it is assumed that the observer's internal representation of the outside world is very sparse, containing only what the observer is currently processing. The present paper presents some clariﬁcations of the theory, and some new implications and predictions that (...) arise from it. (shrink)
Recently a number of studies have shown that under certain circumstances, very large changes can be made in a picture without observers noticing them. What characterizes the experiments showing such "Change Blindness" in visual scenes is the fact that the changes are arranged to occur simultaneously with some kind of extraneous, brief disruption in visual continuity, such as the large retinal disturbance produced by an eye saccade, a shift of the picture, a brief ﬂicker, a "mudsplash", an eye blink, or (...) a ﬁlm cut in a motion picture sequence. These phenomena are attracting an increasing amount of attention from experimental psychologists and from philosophers, because they suggest that humans' internal representation of the visual world is much sparser than usually thought. (shrink)
Call u the triplet of cone quantum catch for the light that is incident on a surface, and v the triplet of cone quantum catch for the light that is reflected off that surface. Philipona & O'Regan (2006) present results from numerical calculations showing that: 1. each surface can be associated with a 3 by 3 matrix A such that the relation v = A u to a very high degree of accuracy for any natural illuminant, 2. the vast majority (...) of such matrices associated with Munsell chips have three real eigenvalues, 3. Munsell chips that are most often given a name in the World Color Survey are chips whose associated matrices have a singular configuration of eigenvalues, as measured by a "singularity index". The conclusion of the paper is that this striking coincidence lends credence to the idea that data about color naming derive from facts about natural lights, surface reflexion properties, and human photopigments, rather than from facts about neural pathways or cortical representations. (shrink)
Overview. Consciousness is often considered to have a "hard" part and a not-so-hard part. With the help of work in artificial intelligence and more recently in embodied robotics, there is hope that we shall be able solve the not-so-hard part and make artificial agents that understand their environment, communicate with their friends, and most importantly, have a notion of "self" and "others". But will such agents feel anything? Building the feel into the agent will be the "hard" part.
Word recognition performance varies systematically as a function of where the eyes fixate in the word. Performance is maximal with the eye slightly left of the center of the word, and decreases drastically to both sides of this 'Optimal Viewing Position'. While manipulations of lexical factors have only marginal effects on this phenomenon, previous studies have pointed to a relation between the viewing position effect and letter legibility: When letter legibility drops, the viewing position effect becomes more exaggerated. To further (...) investigate this phenomenon, we improved letter legibility by magnifying letter size in a way that was proportional to the.. (shrink)
There is an argument promulgated by certain philosophers (notably Dennett 1988, 1991), claiming that from a logical and philosophical point of view the notion of "qualia" makes no sense. On the other hand, other philosophers (e.g. Nagel 1974, Peacocke 1983, and Block 1990) say that qualia must exist since otherwise there would be "nothing it's like" to have sensations: we humans would merely be empty vessels making movements and interacting with our environments, but there would be no inside "feel" to (...) anything. (shrink)
The catastrophe of the eye -- A new view of seeing -- Applying the new view of seeing -- The illusion of seeing everything -- Some contentious points -- Towards consciousness -- Types of consciousness -- Phenomenal consciousness, raw feel, and why they're hard -- Squeeze a sponge, drive a porsche : a sensorimotor account of feel -- Consciously experiencing a feel -- The sensorimotor approach to color -- Sensory substitution -- The localization of touch -- The phenomenality plot -- (...) Consciousness. (shrink)
The paper proposes a way of bridging the gapbetween physical processes in the brain and the ''''felt''''aspect of sensory experience. The approach is based onthe idea that experience is not generated by brainprocesses themselves, but rather is constituted by theway these brain processes enable a particular form of''''give-and-take'''' between the perceiver and theenvironment. From this starting-point we are able tocharacterize the phenomenological differences betweenthe different sensory modalities in a more principledway than has been done in the past. We are also (...) ableto approach the issues of visual awareness andconsciousness in a satisfactory way. Finally weconsider a number of testable empirical consequences,one of which is the striking prediction of thephenomenon of ''''change blindness''''. (shrink)
The most important clarification we bring in our reply to commentators concerns the problem of the “explanatory gap”: that is, the gulf that separates physical processes in the brain from the experienced quality of sensations. By adding two concepts (bodiliness and grabbiness) that were not stressed in the target article, we strengthen our claim and clarify why we think we have solved the explanatory gap problem, – not by dismissing qualia, but, on the contrary, by explaining why sensations have a (...) “feel” and why “feels” feel the way they do. We additionally clarify our views on: internal representations (we claim internal representations cannot explain why sensation has a feel), on behaviorism (we are not behaviorists), on perception and action (we believe there can be perception without action), and on the brain (we believe the brain does do something important in perception). (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)
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.
(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.
Methods. We employed a "flicker" technique, in which an original and a modified image (each of duration 240 ms) continually alternated, with a blank field (duration 80 ms) between each display. Images were all of real-world scenes. One of three kinds of change (appearance/disappearance, color, or translation) was made to an object or region in each scene. Changes were large and easily seen under normal conditions. Subjects viewed the flicker display, and pressed a key when they noticed the change.