“…The contrast threshold measurements were achieved using a temporal two-alternative forcedchoice psychophysical method (Santos, Oliveira, Nogueira, & Simas, 2006;Santos, Simas, & Nogueira, 2007;Wetherill & Levitt, 1965). This method is based on the probability of consecutive correct choices made by participants after the presentation of pairs of stimuli, in this case, in each pair of stimuli, one had only mean luminance (40.1 cd/m2, neutral stimulus) and another contained one of the spatial frequencies (test stimulus).…”