That's true, but this is a way to perceive depth for people who can't view stereoimages (e.g., people blind in one eye). You do experience some amount of depth

That's true, but this is a way to perceive depth for people who can't view stereoimages (e.g., people blind in one eye). You do experience some amount of depth even though each eye is receiving the same information. From http://en.wikipedia.org/wiki/Stereoscopy#Wiggle_stereoscopy http://en.wikipedia.org/wiki/Stereoscopy#Wiggle_stereoscopy: Wiggling works for the same reason that a translational pan (or tracking shot) in a movie provides good depth information: the visual cortex is able to infer distance information from motion parallax, the relative speed of the perceived motion of different objects on the screen. Many small animals bob their heads to create motion parallax (wiggling) so they can better estimate distance prior to jumping.