Read about the different types of optical illusions.
Optical illusions occur when the eye perceives something differently than it is in reality. In other words, something that is viewed or perceived by the eye is translated by the brain to appear as something different.
There are many types of optical illusions. One of the most familiar types is a mirage. A mirage is a phenomenon in which the viewer sees water over the road from a distance, or a pool of water in the desert from a distance. The appearance of water over the road, for instance, is the result of light rays bending through air with different densities. When a person viewing the mirage approaches the area where there is perceived water, the water disappears.
Another common optical illusion occurs when a straw is placed in a glass of water and appears to bend. This is due to light refracting (bending) in water.
An example of an optical illusion related to depth perception is a road coming to a point. Driving down a straight road and looking directly ahead, the road appears to come to a point at the center of the viewer's field of vision. In reality, the road does not come to a point.
A few of the more common brainteaser and puzzler optical illusions are the never-ending staircase, the vase optical illusion, and the spinning flowers optical illusion.
The never-ending staircase is a drawing in which the staircase both ascends and descends depending on how it is viewed. The stairs appear to be going upward in a never-ending motion or downward in a never-ending motion.
The vase optical illusion features either a black vase on a white background or a white vase on a black background. When the viewer focuses on the contrasting color, two silhouettes of opposing human faces appear.
The spinning flower optical illusion is in the form of a flower with progressively smaller petals. Viewers are asked to stare at the dot in the center of the flower until the flower appears to spin.
Optical illusions appear in art and entertainment. Animation is a form of an optical illusion in which the brain perceives a series of drawings as being animated when rapidly viewed in succession. In reality, the drawings are not moving at all.
Optical illusions play a key role in magic. A famous trick based on optical illusion is the disembodied head in a box trick. The disembodied head is in a box placed on a table. The effect is achieved by strategically placed mirrors and lighting that conceal the person sitting under the table with his head in the box