The major theoretical framework relative to the perception of illusory figures is reviewed and discussed in the attempt to provide a unifying explanatory account for these phenomena.

Following the pioneering studies of the receptive field (RF), the concept gained further significance for visual perception by the discovery of input effects from beyond the classical RF. These studies demonstrated that neuronal responses could be modulated by stimuli outside their RFs, consistent with the perception of induced brightness, color, orientation, and motion. Lesion scotomata are similarly modulated perceptually from the surround by RFs that have migrated from the interior to the outer edge of the scotoma and in this way (...) provide filling-in of the void. Large RFs are advantageous to this task. In higher visual areas, such as the middle temporal and inferotemporal lobe, RFs increase in size and lose most of their retinotopic organization while encoding increasingly complex features. Whereas lowerlevel RFs mediate perceptual filling-in, contour integration, and figure–ground segregation, RFs at higher levels serve the perception of grouping by common fate, biological motion, and other biologically relevant stimuli, such as faces. Studies in alert monkeys while freely viewing natural scenes showed that classical and nonclassical RFs cooperate in forming representations of the visual world. Today, our understanding of the mechanisms underlying the RF is undergoing a quantum leap. What had started out as a hierarchical feedforward concept for simple stimuli, such as spots, lines, and bars, now refers to mechanisms involving ascending, descending, and lateral signal flow. By extension of the bottom-up paradigm, RFs are nowadays understood as adaptive processors, enabling the predictive coding of complex scenes. Top-down effects guiding attention and tuned to task-relevant information complement the bottom-up analysis. (shrink)

The article investigates the interplay of moral rules in computer simulation. The investigation is based on two situations which are well-known to game theory: the prisoner''s dilemma and the game of Chicken. The prisoner''s dilemma can be taken to represent contractual situations, the game of Chicken represents a competitive situation on the one hand and the provision for a common good on the other. Unlike the rules usually used in game theory, each player knows the other''s strategy. In that way, (...) ever higher levels of reflection are reached reciprocally. Such strategies can be interpreted as moral rules.Artificial morality is related to the discipline of Artificial Life. As in artificial life, the use of genetic algorithms suggests itself. Rules of behaviour split and reunite as chromosome strings do. (shrink)

This major work covers almost all that has been learned about the acoustics of stringed instruments from Helmholtz's 19th-century theoretical elaborations to recent electroacoustic and holographic measurements.Many of the results presented here were uncovered by the author himself over a 20-year period of research on the physics of instruments in the violin family. Lothar Cremer is one of the world's most respected authorities on architectural acoustics and, not incidentally, an avid avocational violinist and violist.The book - which was published (...) in German in 1981 - first of all meets the rigorous technical standards of specialists in musical acoustics. But it also serves the needs and interests of two broader groups: makers and players of stringed instruments are expressly addressed, since the implications of the mathematical formulations are fully outlined and explained; and acousticians in general will find that the work represents a textbook illustration of the application of fundamental principles and up-to-date techniques to a specific problem.The first - and longest - of the book's three parts investigates the oscillatory responses of bowed strings. The natural nonlinearities that derive from considerations of string torsion and bending stiffness are deftly handled and concisely modeled.The second part deals with the body of the instrument. Special attention is given to the bridge, which transmits the oscillations of the strings to the wooden body and its air cavity. In this case, linear modeling proves serviceable for the most part - a simplification that would not be possible with lute - like instruments such as the guitar.The radiation of sound from the body into the listener's space, which is treated as an extension of the instrument itself, is the subject of the book's final part.Lothar Cremer is Professor Emeritus at the Technical University of Berlin, where he served as director of the Institute for Acoustical Engineering. (shrink)

Die digitale Transformation erfasst die Medien der Literatur und Literaturkritik in unterschiedlicher Geschwindigkeit. Die Substituierung der gedruckten Zeitung, der Stammheimat der Literaturkritik, durch digitale Formate ist weit vorangeschritten. Auf dem Buchmarkt ist das gedruckte Hardcover nach wie vor ein relativ stabiles Element. Der Beitrag kommentiert diese Differenz in medienhistorischer Perspektive.