Hue, saturation, and brightness scaling from spots targeted to single cones. (A) AOSLO image from S20076 at 1.5° eccentricity. Numbers indicate the five cone centers that were selected for targeting during the experimental session. A roughly equal proportion of rods and cones are visible at this eccentricity (rods have been pseudocolored purple). Scale bar indicates 1 arcmin. (B) On each trial, a flash was targeted at one of the selected locations and trials were randomly interleaved between the five locations. After each flash, the subject rated brightness on a scale from 0 to 5 and data were fit according to Steven's law (Equation 5). A brightness rating greater than zero indicated the trial was seen. (C) FoS data were fit with Weibull functions (Equation 1). (D) Subjects additionally reported the hue and saturation of the flash with a scaling procedure. The results from hue and saturation scaling from the five tested cones are plotted in a uniform appearance diagram (Gordon et al., 1994; Abramov et al., 2009). Each cone was tested at three intensities and the average response across all seen trials is plotted for each intensity. Error bars represent SEM; some error bars are smaller than the size of the symbol. Colors denote cone type (green = M cones, red = L cones).