Samenvatting
This study investigated the brightness of colored lights that were viewed against a dark background, which is the way in which traffic and navigation signals, automobile tail lights, etc., are seen in everyday life. Brightness of 2-deg centrally fixated monochromatic lights was measured by magnitude estimation, delayed matching, and conventional heterochromatic photometry. The photometry data resemble the CIE photopic relative luminous efficiency function, but both the estimation and delayed-matching procedures result in substantially higher sensitivities to short-wavelength stimuli.