Early Theories of Binocular Rivalry
Various theories were proposed to account for binocular rivalry. Porta and Dutour took it as evidence for an ancient theory of visual perception that has come to be known as suppression theory. Its essential idea is that, despite having two eyes, we see only one of everything (known as singleness of vision) because we see with one eye at a time. According to this theory, we do not normally notice the alternations between the two eyes because their images are too similar. By making the images very different, Porta and Dutour argued, this natural alternation can be seen. Wheatstone, on the other hand, supported the alternative theory of singleness of vision, fusion theory, proposed by Aristotle. Its essential idea is that we see only one of everything because the information from the two eyes is combined or fused. Wheatsone also discovered binocular stereopsis, the perception of depth arising from the lateral placement of the eyes. Wheatstone was able to prove that stereopsis depended on the different horizontal positions (the horizontal disparity) of points in the images viewed by each eye by creating the illusion of depth from flat depictions of such images displayed in his stereoscope. Such stereopsis is impossible unless information is being combined from each eye. Although Wheatstone's discovery of stereopsis supported fusion theory, he still had to account for binocular rivalry. He regarded binocular rivalry as a special case in which fusion is impossible, saying "the mind is inattentive to impressions made on one retina when it cannot combine the impressions on the two retinae together so as to occasion a perception resembling that of some external object" (p. 264).
Other theories of binocular rivalry dealt more with how it occurs than why it occurs. Dutour speculated that the alternations could be controlled by attention, a theory promoted in the nineteenth century by Hermann von Helmholtz. But Dutour also speculated that the alternations could be controlled by structural properties of the images (such as by temporary fluctuations in the blur of one image, or temporary fluctuations in the luminance of one image). This theory was promoted in the nineteenth century by Helmholtz's traditional rival, Ewald Hering.
Read more about this topic: Binocular Rivalry
Famous quotes containing the words early, theories and/or rivalry:
“The secret of heaven is kept from age to age. No imprudent, no sociable angel ever dropt an early syllable to answer the longings of saints, the fears of mortals. We should have listened on our knees to any favorite, who, by stricter obedience, had brought his thoughts into parallelism with the celestial currents, and could hint to human ears the scenery and circumstance of the newly parted soul.”
—Ralph Waldo Emerson (1803–1882)
“The real trouble about women is that they must always go on trying to adapt themselves to men’s theories of women, as they always have done. When a woman is thoroughly herself, she is being what her type of man wants her to be. When a woman is hysterical it’s because she doesn’t quite know what to be, which pattern to follow, which man’s picture of woman to live up to.”
—D.H. (David Herbert)
“Sisters define their rivalry in terms of competition for the gold cup of parental love. It is never perceived as a cup which runneth over, rather a finite vessel from which the more one sister drinks, the less is left for the others.”
—Elizabeth Fishel (20th century)