1) Optical device 
A pseudoscope is a binocular optical instrument that reverses depth perception. It is used to study human stereoscopic perception. Objects viewed through it appear inside out, for example: a box on a floor would appear as a box shaped hole in the floor. It typically uses sets of optical prisms, or periscopically arranged mirrors to swap the view o...
• (n.) An instrument which exhibits objects with their proper relief reversed; -- an effect opposite to that produced by the stereoscope.
Pseu'do·scope noun [ Pseudo- + -scope .] (Opt.) An instrument which exhibits objects with their proper relief reversed; -- an effect opposite to that produced by the stereoscope. Wheatstone. 
an optical instrument for producing an image in which the depth or relief of an object is reversed. Cf.