Tsukuba Depth Perception
Method 1: Cross Viewing
Cross your eyes and adjust your distance from the two images until the two images blend into one and you can perceive 3D. For those who've never done this before, the idea is to focus on a point very close to your face (thus crossing your eyes). At an appropriate distance from the two images, your right eye will be looking directly at the left image and your left eye will be looking directly at the right image. Once that is achieved, the two images should merge into a single view with depth perception. It's recommended not to maintain this pose for too long as people have been known to stay cross-eyed for hours afterwards.
Method 2: Divergent Viewing
Now, instead of crossing your eyes, just stare straight ahead. Make sure your left eye is staring directly at the left image and your right eye is staring directly at the right image. In other words, don't focus on any one point with both eyes. Again, when performed properly, the two images will merge into one, thus enabling you to perceive 3D.
Many people find Method 2 easier than Method 1, since it doesn't require crossing eyes. Magic Eye also works under the same principles so people who are adept at viewing Magic Eye images will be more familiar with this Method 2. This phenomenon gives strength to the argument that two corresponding images generated from a binocular pair of cameras should be sufficient for a computer to perceive depth.