We identify two aspects of the problem of maintaining perceptual stability despite an observer's eye movements. The first, visual direction constancy, is the (egocentric) stability of apparent positions of objects in the visual world relative to the perceiver. The second, visual position constancy, is the (exocentric) stability of positions of objects relative to each other. We analyze the constancy of visual direction despite saccadic eye movements.Three information sources have been proposed to enable the visual system to achieve stability: the structure (...) of the visual field, proprioceptive inflow, and a copy of neural efference or outflow to the extraocular muscles. None of these sources by itself provides adequate information to achieve visual direction constancy; present evidence indicates that all three are used.Our final question concerns how information processing operations result in a stable world. The three traditionally suggested means have been elimination, translation, or evaluation. All are rejected. From a review of the physiological and psychological evidence we conclude that no subtraction, compensation, or evaluation need take place. The problem for which these solutions were developed turns out to be a false one. We propose a “calibration” solution: correct spatiotopic positions are calculated anew for each fixation. Inflow, outflow, and retinal sources are used in this calculation: saccadic suppression of displacement bridges the errors between these sources and the actual extent of movement. (shrink)

The phenomena referred to by the term attention were not discovered by scientific psychology. They were discovered and described within philosophy and gently handed over to the emerging academic psychology of the nineteenth century. The main contributors and contributions to the delineation and construction of attention as an empirical phenomenon and a topic for theorizing were Aristotle, who noticed that not all that reaches the senses is clearly perceived; Augustine, who interpreted attention as an effort of the soul; Descartes, who (...) distinguished active attention from passive attention; and Leibniz, who discussed the relation between attention, perception, and consciousness. (For further information on attention's philosophical past the reader is referred to Neumann's (in press) brief history of this philosophical past that is badly in need of an English translation.). (shrink)

The explanatory gap refers to the lack of concepts for understanding “how it is that . . . a state of consciousness comes about as a result of irritating nervous tissue.” By assuming that there are colours in the outside world, Block needlessly widens this gap and Lycan and Kitcher simply fail to see the gap. When such assumptions are abandoned, an unnecessary and incomprehensible constraint disappears. It then becomes clear that the brain can use its own neural language for (...) representing aspects of the outside world. While this may not close the gap, it becomes clearer where we need new concepts. (shrink)

Everybody knows the phenomena summarized with the term attention: concentration, focalization, limitation, selection, and intensification . The explanation of these phenomena is, however, a different matter. Problems easily arise with regard towhathas to be explained and with regard to thestyleof explanation. A problem of the first kind is the “methodology of ‘bad focus’”: the explanation starts with and is fixated on an intuitively striking but nonessential behavioral feature or cognitive achievement. A problem of the second kind is a “virtus dormitiva” (...) explanation: the explanation starts with emphasizing one aspect of the observed phenomena, the emphasized aspect receives an interesting and suggestive name, and that name with its connotations is used as a concept in the explanation. At the start of contemporary, behavior-based, information processing psychology, avirtus dormitivaexplanation infiltrated the functional accounts of the phenomena of attention; the empirical observation that people show performance limitations was translated into the theoretical concept of a communication channel with a limited capacity. That limited capacity notion became the core concept in what can be called the standard theory of attention. This standard theory of attention faced severe difficulties in explaining the guidance of attention by the information processor's goals and intentions. Subsequent modifications, concerned with removing these difficulties, revealed that selection, guided by goals and intentions, is the essential behavioral feature and that the observed performance limitations are a result of this selection. So, the limited capacity theorizing was not only plagued by avirtus dormitivaexplanation, it also suffered from the methodology of bad focus. (shrink)