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Simone Gori; Imperfect scission in achromatic transparency. Journal of Vision 2005;5(8):567. doi: 10.1167/5.8.567.
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© ARVO (1962-2015); The Authors (2016-present)
In achromatic transparency, Beck and Ivry (1988)* have found that color scission is not perfect, i.e., observers report that the color of the background seen through the transparent region differs from the color of the background seen directly. The present study was undertaken to define the relations between stimulus luminances that produce such an imperfect scission. Following a black fixation point, experimental stimuli were displayed for 1 sec on a monitor screen. Each consisted of a bicolored rectangle (18° × 21.5°) with a smaller transparent square (7° × 7°) placed on the center of the rectangle. Let P and Q be the luminances of the left and right halves of the transparent region and let A and B be the luminances of the left and right halves of the rectangle outside the transparent region, respectively. Four values for A, B, P and Q were present. For each of the combinations of these values a stimulus was constructed with the restrictions that A had to be always smaller than P, Q, and B, that B had to be always greater than Q and P, and that P had to be always smaller than Q (thus A < P < Q < B). Eighteen naive subjects served as observers. To each of them, the entire series of stimuli was shown twice with stimuli presented randomly. Subjects were asked to report whether the colors seen through the transparent region on the left and right halves of the background were the same or were different from the colors seen directly on the left and right halves of the background, respectively. All subject showed imperfect scission. Mean response proportions indicate clearly that the relation A / P, when subjects look at the left half of the transparent square, and the relation B / Q, when subjects look at the right half of the transparent square, are the only factors that determine the extent of color scission.
1988 P & P 44 585–594
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