Figure 2.

Stimulus conditions. Each panel shows one stimulus condition. The right side of each box illustrates the sinusoidal variation of the binocular variables during one period, for V, R, and H (blue, green, and red line respectively). Optic flow was present in all conditions. Note that peak velocity of the flow coincides with zero crossing of V, R, and H (Figure 1A). The left side of each box shows a top view of the eyes, together with the extreme simulated positions (phase angles: 0.5 π (filled blue dot) and 1.5 π (blue circle) of the Vieth-Muller torus (red circle segments), and the eye fixation target (blue dot, blue circle). Note that in panels V₂R₄H₂ and V₄R₆H₂ the movements of the VM surface and the fixation point are opposite at all times.