Flicker photometry: residual minimum flicker.

We show that when all possible optical artifacts are eliminated in a flicker photometric procedure, there is still a residual minimum flicker after color fusion occurs. Our stimuli were alternated with approximately rectangular pulses; we obtained results contrary to those of a previous report in which the stimuli were alternated sinusoidally. In a subsidiary test using a computer-generated cosine wave on a RGB monitor, one observer perceived no residual flicker but a second observer did.