is incorrect. These misinterpretations are called illusions. When we witness an illusion, we perceive something that does not correspond to what is actually out there-what exists in the real world. Illusions fool us as they convince us of things that are untrue. The dictionary interpretation of the term "illusion" states that is a sensory perception that causes a false or distorted impression, or a misrepresentation of a real sensory stimulus. While this may be correct, most psychologists will be quick to point out that this definition is incomplete. In examining perceptual illusions, one must also consider a number of phenomena where there is no necessary incorrect interpretation of a stimulus but rather that there are two or more quite different interpretations from a single stimulus, but never more than one at a given moment. In these cases two or more different interpretations of a figure can be seen, but never at the same time.
             Illusions offer a nice window into perception, because they can reveal the limitations of our perceptual systems in a way that studying normal perceptual processes do not. We do not see many illusions in the real world because our visual system has evolved in such a way as to resolve the ambiguity that is inherent in a retinal image. Visual perception is essentially an ambiguity–solving process. However, mistakes can happen and it is in considering such mistakes that our perceptual abilities and its shortfalls become apparent. Sometimes, an illusion occurs when there is not enough information
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