stereogram

n. A stereogram is any visual pattern that contains binocular disparity. Because human observers view the world with two frontally oriented eyes, each retina receives a different perspective view of environmental objects and surfaces. The small differences between the two eyes' retinal images are referred to as binocular disparities. Traditionally, stereograms were viewed using a stereoscope. Charles Wheatstone invented the mirror stereoscope and in 1838 published the first stereograms depicting 3-D objects. The stereograms used today are typically presented using computers. In the early 1960s Bela Julesz developed computergenerated random-dot stereograms. These stereograms are unique in that the depicted 3-D objects and surfaces are defined only by the pattern of binocular disparities. No monocularly visible object contours or outlines are present within either individual eye's retinal image. In modern psychological research, random-dot stereograms are usually preferred because the depicted objects and scenes are defined only by binocular disparity. – JFN