In Experiment 1, we mimicked an observer’s motion toward/away from a single fronto-parallel surface. The stimuli of Experiment 3 were exactly the same as in Experiment 1 except that three front-parallel surfaces were used in this experiment to explore how the factor of additional depth information might have an effect on perceived shift of the centres of expanding and contracting optic flow patterns in the peripheral retina. There are two flashes below to demonstrate the basic stimuli used in this experiment. The upper flash is a schematic representations of an expanding optic flow in the first interval and a contracting optic flow in the second interval. The lower flash is a schematic representations of a contracting optic flow in the first interval and an expanding optic flow in the second interval. Participants' task is to indicate which interval contains an optic flow with its FOC/FOE closer to the central fixation point (equal close in these examples). In both flashes, the two optic flow patterns are presented only in one of the four visual quadrants. In the other three conditions, the two optic flow patterns were presented in the other three visual quadrants.