THE EFFECT OF FLICKER ON FOVEAL AND PERIPHERAL THRESHOLDS FOR OSCILLATORY MOTION

This study evaluated the influence of superimposed luminance flicker o n the detection of oscillatory motion. Thresholds for oscillatory moti on were determined in the fovea and at 2, 6 and 25 deg in the right fi eld for a small luminous target with and without sinusoidal luminance flicker. At the fovea, flicker modulation up to 80% at frequencies fro m 1.5 to 9 Hz had no effect on motion detection, except for oscillator y motion at a frequency of 8 Hz, for which thresholds were elevated by about 0.2 log units. In the periphery, bicker elevated motion thresho lds up to 0.3-0.4 log units at low and moderate frequencies of oscilla tion at all locations tested. However, both foveal and peripheral moti on thresholds were unaffected by flicker when the luminance of the tar get was reduced. The absence of a robust effect of target flicker on m otion thresholds may be accounted for in part by the comparison of act ivity across a large population of motion-detecting neurons with diffe rent direction preferences. Another contributing factor may be the exi stence of foveal velocity- and position-detecting mechanisms with simi lar sensitivities.