Illusions

Our perceptions are not always veridical -- that is, they do not always match physical reality with complete accuracy. On some occasions, we fail to interpret the sensory information we receive correctly, and this results in a mismatch between an actual physical stimulus and our perception of it. These systematic misperceptions, resulting from misinterpreting the information received through our sense organs, are generally known as illusions. Illusions are experienced, more or less, by all of us. They result from an actual external stimulus situation and tend to generate a broadly similar kind of experience in each individual who views them -- which is part of why illusions are also sometimes described as "primitive organisations". Although illusions can, in principle, be experienced through the stimulation of any of our senses, psychologists have studied them far more thoroughly in the visual domain than in any other sense modality. …