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Sérgio Nascimento, João Linhares, Catarina João, Jorge Santos, Vasco de Almeida; Testing perceptual models of dichromacy and anomalous trichromacy with a computer-based color-vision test. Journal of Vision 2015;15(12):1313. doi: 10.1167/15.12.1313.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this work was to evaluate existing perceptual models of inherited red-green color deficiencies by assessing the extent to which they predict color discrimination. For dichromacy, the model was the one proposed by Brettel at al. (1997 J. Opt. Soc. Am. A, 2647). For anomalous trichromacy, the assumption tested was that equal stimulations of photoreceptors produce the same color perception for normal and anomalous observers. The color test was developed in-house and was inspired by the Universal Colour Discrimination Test (Ripamonti et al., 2013 J Vis 13(9): 1023). The stimuli were displayed on a calibrated CRT monitor (GDM-F520, Sony Corp.) controlled by a video board (ViSaGe Visual Stimulus Generator; Cambridge Research Systems). The stimulus was a square target of variable color on a white background. Both target and background were made of small circles of random diameter and subtended 17 deg and 5 deg, respectively. The luminance of the circles was assigned randomly from the interval 6-16 cd/m2. In the standard condition, the color of the target varied along 20 equally-spaced directions in color space around the color of the background. Ten protanopes, five deuteranopes, five deuteranomalous and two protanomalous observers were tested in this condition. In the simulation condition, background and target had the corresponding colors of the standard condition predicted by the models. Twelve normal observers were tested in this condition. In both conditions discriminations thresholds in each direction were estimated using a straircase procedure. The quality of model was evaluated by comparing the results obtained in the two conditions. For dichromacy, the thresholds for the two conditions were similar, indicating that the model describes well dichromats’ perception. For anomalous trichromacy, however, the thresholds in the two conditions were clearly different, suggesting that some additional normalization of the visual system may need to be considered.
Meeting abstract presented at VSS 2015
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