The effect of background luminance on Cone Sensitivity Functions

Abstract

Wald (1964, 1966) developed an increment threshold technique to obtain test sensitivity functions for the cone spectral sensitivities. He used bright chromatic backgrounds to differentially adapt two cone types leaving the third cone relatively more sensitive. The technique was adapted by Marré for clinical use (Marré, 1972; Marré and Marré, 1972, 1973). Subsequent studies (Eisner and Macleod, 1981; Ingling and Martinez, 1981; Eisner, 1982) suggested that rapid flicker (>15Hz) is a more effective test stimulus for isolation of the spectral sensitivity of the middle-wavelength sensitive (MWS) and long-wavelength sensitive (LWS) cone types. However, isolation of MWS cones at longer wavelengths is not complete even with a rapid flicker rate (Lutze, Pokorny and Smith, 1987). In this study, linear combinations of cone sensitivity functions were fitted to sensitivity functions obtained using a Wald-Marré technique with varying background luminance levels.