ERG responses and the Ferry-Porter law

The Ferry-Porter law states that the psychophysically measured critical flicker fusion frequency (CFF) is linearly correlated with the logarithm of the mean luminance. We studied the relationship between the CFFs of L- and M-cone driven ERGs (five normal trichromats; sinusoidal modulation; 18% cone contrast) and mean luminance. The measurements were performed at seven mean luminances between 2.84 and 284<i>c</i> <i>d</i>/<i>m</i> ². Close to the CFF, the ERG amplitudes versus temporal frequency could be described by a simple exponential function. The CFFs were higher for L- than for M-cone driven ERGs and depended linearly on the logarithm of the mean luminance (i.e., adhered to the Ferry-Porter law) with steeper slopes compared to psychophysical measurements.