Spectral sensitivity curves were established for three intensity levels above scotopic threshold with a twodegree field placed ten degrees from fixation against a dark surround. These curves were compared with the minimum scotopic luminosity curve determined for the same retinal position for each observer. The results showed that (1) there is a range of intensities over which relative spectral sensitivity does not change appreciably from the scotopic luminosity function, (2) there are irregularities in these mesopic curves which may be attributed to cone activity, and (3) the first change in spectral sensitivity with increased intensity is found in the long-wavelength half of the spectrum.
Jo ANN SMITH KINNEY, "Sensitivity of the Eye to Spectral Radiation at Scotopic and Mesopic Intensity Levels," J. Opt. Soc. Am. 45, 507-513 (1955)