Binocular Rivalry

The modern physiological optics introduces the notions related to the conditions of fusion of binocular images by the concept of correspondence, due to Christiaan Huygens, and by an experiment attributed to Christoph Scheiner. The conceptualization of this experiment dates, in fact, back to Ptolemy and Ibn al-Haytham. The present paper surveys Ibn al-Haytham's knowledge about the mechanisms of binocular vision. The article subsequently explains why Ibn al-Haytham, a mathematician, but here an experimenter, did not give the circular figure of the (...) theoretical horopter, construction due to Gerhard Vieth and Johannes Müller. But, on the other hand, it is clear that Ibn al-Haytham's experimental study puts in place the notion of corresponding points, the cases of homonymous and cross diplopia, and even prepares the discovery of Panum area. (shrink)

The reality of the soul, its levels and actions, and its relation to the body havealways been among the most important philosophical issues, andevidence for this may be found even in the most ancient philosophicaldeliberations of the Greeks and others.In the philosophical traditions of the Islamic world as well, serious attemptshave been made to present a “science of the soul” which is in accord with thespirit of Islamic philosophical sciences. In the Transcendent Philosophy, onthe other hand, a version of science (...) of the soul has been presented whichboth justifies the concrete sphere of “the immaterial and material soul” anddescribes “the soul’s becoming and seeking for perfection”. In addition, it isfully consistent with the components and overall structure of theTranscendent Philosophy.Based on doctrines of principiality of existence, motion in substance, bodilyorigination and spiritually subsistence of the soul, Mulla Sadra depicts man’ssoul and its station in such a way which is free from usual inconsistencies ofphilosophical traditions in this regard. At the same time, based on the Bookand tradition, he opens a new window to man’s existence through which theexistential dimensions of man are seen in correspondence and as beingsimilar to the whole cosmos. Though, in this way, Mulla Sadra has madeuses of the Peripatetic and Illuminationist traditions of his forerunners, hisown innovations are unrivalled and exceptionally strong. (shrink)

“Source monitoring” theory is applied to the turn-of-the-century argument that, whenever binocularly fused patterns are self-consciously apperceived, both eyes' monocular sensations are consciously perceived. According to monitoring theory's refinement of the argument, binocularly apperceived patterns are accompanied by selfconsciousness that one is perceiving patterns , whereas monocular sensations are accompanied by no self-consciousness of their source. In the current test of this refined argument, 32 subjects were monocularly presented with 6 letters of the alphabet, while binocularly fusing 6 different letters, (...) and were subsequently required to discriminate these 12 letters from 6 other letters that they had visually imaged. Consistent with monitoring theory, the results of experimental testing suggest that binocularly fused letters are neurally monitored as “peripheral,” self-consciously experienced as “perceived,” and subsequently remembered as not “imaged.” The results further suggest that, during such binocular apperception, monocular data are not totally unconscious-like computer data-but are consciously experienced as “sourceless” sensations that are memorially confused with visually imaged sensations. (shrink)

The target article retains the traditional account of saccades as conjugate eye movements. However, recent single-unit recordings of premotor cells in the saccade pathway (excitatory burster neurons [EBNs]) found that they do not encode conjugate eye velocity, but rather, monocular eye velocity. These data argue against the traditional concept of saccades as inherently conjugate. Instead, they suggest a monocular mechanism in the sensorimotor transformation stage of saccade generation. This commentary will discuss the implications of these data for the saccade generation (...) model proposed in Findlay & Walker's target article. (shrink)