An analysis was made of the impulse discharge patterns-evoked by sinusoidal luminance modulation-of single cells in the lateral geniculate nucleus of the macaque monkey. The goal was to determine whether a correspondence could be observed between flicker detection by human subjects in psychophysical experiments and electrophysiological measurements of discharge patterns of single cells of the lateral geniculate nucleus. We found that the average discharge patterns of single cells exhibited the following behavior when mean retinal illumination was changed: In the low-frequency region (less than about 10 Hz) the response strength (impulses/sec) is independent of the mean luminance, in accordance with Weber's law; in the high-frequency region (above about 10 Hz) the response depends on the absolute modulation amplitude, in accordance with the Ferry-Porter law. Therefore the main features of human critical flicker frequency data are already present in the cellular (lateral geniculate nucleus) response of the macaque monkey. However, the steepness of high frequency fall-off in the response characteristics of these cells is much less than the corresponding fall-off in the human critical-flicker-frequency curves.