Awesome Facts About Illutions

ILLUSIONS

Illusion comes from the Latin word Illudere with means “ to mock” or “make fun of” . Illusions trick us into seeing something different than actually what is there.

What Are Optical Illusions?

Optical illutions refers to any illusion that makes

a false impression to mislead the human visual system into perceiving what is present.

DIFFERENT TYPES OF ILLUSIONS

Physiological illusions Physiological illusions, such as the afterimages following bright lights or adapting stimuli of prolonged alternating patterns (contingent perceptual after-effect, CAE), are the effects on the eyes of prolonged stimulation of a specific type - brightness, tilt, colour, movement and so on. The theory is that stimuli have individual dedicated neural paths in the visual cortex for the early stages of visual processing, repetitive stimulation of only a few channels misleads the visual system.

Cognitive illusions Cognitive illusions are more interesting and well-known. Instead of demonstrating a physiological base they interact with different levels of perceptual processing, in-built assumptions or 'knowledge' are misdirected. Cognitive illusions are commonly divided into ambiguous illusions, distorting illusions, paradox illusions or fiction illusions. They often exploit the predictive hypotheses of early visual processing.

Ambiguous illusions Ambiguous illusions are pictures or objects that offer significant changes in appearance. Perception will 'switch' between the alternates as they are considered in turn as available data does not confirm a single view. The Necker cube is a well known example, the motion parallax due to movement is being misinterpreted, even in the face of other sensory data.

Distorting illusions Distorting illusions are the most common, these illusions offer distortions of size, length or curvature. They were simple to discover and are easily repeatable. Many are physiological illusions, such as the Cafe wall illusion which exploits the early visual system encoding for edges. Other distortions, such as coverging line illusions, are more difficult to place as physiological or cognitive as the depth-cue challenges they offer are not easily placed. All pictures that have perspective cues are in effect illusions. Visual judgements as to size are controlled by perspective or other depth-cues and can easily be wrongly set.

Paradox illusions Paradox illusions offer objects that are impossible or paradoxical, such as the Penrose triangle or impossible staircase seen, for example, in the work of M. C. Escher. The triangle is a illusion dependent on a cognitive misunderstanding that adjacent edges must join. They occur as a byproduct of perceptual learning.

Fiction illusions Fiction illusions are the perception of objects that are genuinely not there to all but a single observer, such as those induced by schizophrenia or hallucinogenic drugs.