Fig. 5.

Neuronal and psychophysical sensitivity show similar dependence on reference luminance. A: average precision of population encoding of luminance as a function of number of units, for each reference luminance for V1 (left, 18 sessions) and V4 data (right, 137 sessions). Performance of a neuronal decoder at discriminating 0.10 luminance increments as a function of the reference luminance and the number of units included. Data points represent the mean across all paint trials for data sets from V1 and V4 for 10,000 random draws per base luminance and population size, per data set. Error bars are the SE of the mean across data sets. B: for the conditions where both disks were presented in the paint checkerboard, this plot shows the average (across subjects/determinations) probability of correctly judging a luminance increment of 0.10 as lighter, for the three reference luminances (0.25, 0.50, and 0.75) used in the psychophysical studies. These data are taken from the paint-paint checkerboard pairings. Error bars show ±1 SE taken across subjects/determinations (n = 6, see Fig. 2C).