Temporal frequency tuning of S+ and S− cells. A, Average (see Materials and Methods) temporal frequency tuning of S+ (gray circles) and S− cells (black circles) for S-cone isolating modulation. B, Same as A but for achromatic gratings. The average temporal frequency tuning of P-cells (open circles) for achromatic gratings is shown for comparison. Error bars in the x and y (in most cases, smaller than the data point) directions report SEMs.