Perceived flicker rate of suprathreshold stimuli: influences of spatial-frequency content and modulation amplitude.

A number of experiments were conducted in which observers had to discriminate the apparent flicker rates of temporally modulated gratings and flickering homogeneous fields. When both intramodal- and cross-modal-matching procedures were used, apparent flicker rate was found to be consistently higher for countermodulating gratings than for homogeneous fields of the same temporal frequency. Also, the apparent flicker rate of countermodulating gratings tended to increase as spatial frequency increased. These effects are more pronounced at low rates of temporal modulation than at high rates and are not dependent on variations in the stimulus's apparent modulation amplitude.