With the eye adapted to (representative) colored backgrounds, 15-Hz flicker photometry and flicker thresholds yielded spectral-sensitivity curves identical within error. Flicker photometry is the more precise measure.
© 1982 Optical Society of America
A. Eisner, "Comparison of flicker-photometric and flicker-threshold spectral sensitivities while the eye is adapted to colored backgrounds," J. Opt. Soc. Am. 72, 517-518 (1982)