Luminosity and CFF in Deuteranopes and Protanopes*

The absolute-threshold spectral-sensitivity curves of deuteranopes and protanopes were compared with the luminosity curves obtained by heterochromatic flicker photometry and side-by-side brightness matching. The luminosity measurements between 500 and 700 nm paralleled the absolute-threshold spectral sensitivity over a luminance range of 4–400 td. CFF–log I functions were obtained at six spectral wavelengths from deuteranopes and protanopes. At 580 nm, where the absolute threshold gave identical estimates of sensitivity for deuteranopes and protanopes, the deuteranopes showed a steeper CFF–log I slope than protanopes. At 4000 td, the deuteranopes had CFF thresholds of 50 cps compared with 40 cps for protanopes.