If you have not seen it yet, have a look at the great site 92 Visual Phenomena & Optical Illusions by Michael Bach. A quote:
»Optical illusion« sounds pejorative, as if exposing a malfunction of the visual system. Rather, I view these phenomena as bringing out particular good adaptations of our visual system to standard viewing situations. These adaptations are »hard-wired« in our brains, and thus under some artificial manipulations can cause inappropriate interpretations of the visual scene. As Purkinje put it: »Illusions of the senses tell us the truth about perception« (cited by Teuber 1960).
[...] Optical Illusions (micromath.wordpress.com) [...]
By: Optical Illusions to Please the Eye « Leodini's Inner Magic on June 3, 2011
at 1:13 pm
[...] Optical Illusions « Mathematics under the MicroscopeDescription : »Optical illusion« sounds pejorative, as if exposing a malfunction of the visual system. Rather, I view these phenomena as bringing out particular good adaptations of our visual system to standard viewing situations. …http://micromath.wordpress.com .. [...]
By: optical illusions - LATEST TECHNOLOGY – LATEST TECHNOLOGY on June 22, 2011
at 9:23 pm