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P.T. Quaid, J.G. Flanagan; The Effect of Eccentricity on Flicker Defined Form Phase Contrast Thresholds . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3689.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the effect of eccentricity on Flicker Defined Form (FDF) contrast thresholds, generated using the phantom contour illusion, to other psychophysical stimuli matched in the temporal or spatial domain.
The effect of eccentricity on FDF was compared (n = 3, 1 female, ages 24, 26 and 29 years) to other psychophysical stimuli in the temporal and spatial domain. All stimuli were 5o diameter circles. FDF was generated using low, medium and high numbers of random dots (1, 3 and 5 dots/degree2). Stimuli matched in the temporal domain (16.67Hz) included; (i) frequency doubling (using 0.25cpd and 1cpd) and (ii) square wave flicker. Stimuli matched in the spatial domain included: (i) identical dot field generated for FDF (0Hz) using low, medium and high numbers of random dot; (ii) sinusoidal gratings of 1, 4 and 6 cpd; (iii) gaussian patch and (iv) square wave patch.
FDF showed a significantly different relationship with eccentricity compared to the other psychophysical stimuli examined. Thresholds significantly improved with increasing eccentricity using a low random dot number, whereas no significant change in threshold was observed using medium and high random dot numbers (p>0.211). All other stimuli used revealed a significant increase in threshold with increasing eccentricity (p<0.05).
FDF exhibits a significantly different relationship to eccentricity compared to the other size–matched psychophysical stimuli used. This difference is related to the number of random dots used to generate FDF.
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