Schematic illustration of temporal figure-ground-segmentation.

The task of the observer was to indicate the side of the rectangle. The grey accentuation of the rectangle is only for illustrational purposes and was not displayed during the experiment. (A) In the beginning of the measurement there is a fixed difference (Δt) between target and background flips, defining also the frequency of flips. By reducing Δt either while (B) keeping the basis frequency constant (phase reduction) or by (C) reducing Δt and therefore increasing the frequency (frequency modulation), the task becomes gradually more difficult.