Figure 9.

The stimulus in Experiment 3. A random-dot stereogram depicting a vertical hinge in an open-book configuration. Observers indicated whether the perceived hinge angle was greater or less than 90 deg. The task could not be performed monocularly. The reader can see the 3D hinge by cross-fusing the stimulus. The experiment used a red stimulus on a black background but was reproduced here as black on white for clarity. The hinge is shown in plan view in Figure 1A.