An optical illusion (also called a visual illusion) is characterized by visually perceived images that are deceptive or misleading. The information gathered by the eye is processed by the brain to give a percept that does not tally with a physical measurement of the stimulus source. There are three main types of illusion – literal optical illusions that create images that are different from the objects that make them, physiological illusions that are the effects on the eyes and brain of excessive stimulation of a specific type – brightness, tilt, color, movement, and cognitive illusions where the eye and brain make unconscious inferences.

Physiological illusionsPhysiological illusions, such as the afterimages following bright lights or adapting stimuli of excessively longer alternating patterns (contingent perceptual aftereffect), are presumed to be the effects on the eyes or brain of excessive stimulation of a specific type – brightness, tilt, color, movement, etc. The theory is that stimuli have individual dedicated neural paths in the early stages of visual processing, and that repetitive stimulation of only one or a few channels causes a physiological imbalance that alters perception.

Cognitive illusions are assumed to arise by interaction with assumptions about the world, leading to “unconscious inferences”, an idea first suggested in the 19th century by Hermann Helmholtz. Cognitive illusions are commonly divided into ambiguous illusions, distorting illusions, paradox illusions, or fiction illusions.

Fictional illusions are defined as the perception of objects that are genuinely not there to all but a single observer, such as those induced by schizophrenia or a hallucinogen. These are more properly called hallucinations.

Paradox illusions are generated by objects that are paradoxical or impossible, such as the Penrose Triangle. The triangle is an illusion dependent on a cognitive misunderstanding that adjacent edges must join.

Distorting illusions are characterized by distortions of size, length, or curvature. A striking example is the Cafe wall illusion.

So how many was there…? Would you believe there are zero black dots? Count The Black Dots

The Herman Grid Illusion is best explained using a biological approach. Lateral inhibition, where in the receptive field of the retina light and dark receptors compete with one another to become active, has been used to explain why we see bands of increased brightness at the edge of a color difference when viewing Mach bands. Once a receptor is active it inhibits adjacent receptors. This inhibition creates contrast, highlighting edges. In the Hermann grid illusion the grey spots appear at the intersection because of the inhibitory response which occurs as a result of the increased dark surround.

Believe It or Not… – – – Every Line Is Straight! – – –

The Penrose Triangle

The Penrose triangle is considered the impossible figure.

The Penrose triangle appears to be solid on the page, but it cannot be built.

Albert Einstein Marilyn Monroe Illusion

When you look at this picture close range you see Albert Einstein .

Now stand up and take several steps back, roughly 15 feet away,

It will become… Marilyn Monroe .



Gray Circle Illusion

Stare at the black dot…



Did you see the Gray circle disappear?



Stare at the red dot on this woman’s nose for thirty seconds. Then, look over at a blank white space (a piece of paper or an empty browser tab will do). Did you see the “correct” version of the image? Here’s how it works: stare long enough at an object and the eye’s photoreceptors (particularly the color-sensitive cone cells) lose sensitivity from overstimulation. Divert the eyes to a blank space, and the surrounding cone cells send out a much stronger signal. The brain interprets this discrepancy as looking at the precise opposite colors, in what is known as a ‘negative afterimage.’ Nifty, no?

This is a still image, but if you move your eyes around the central square pattern, the stars will seem to move. The effect is due to a phenomenon that’s colloquially called “eye jitter.” The eyes, constantly moving by imperceptible amounts, amplify the difference between the two patterns and create the illusion of motion



Believe it or not, the “green” and “blue” colors in this spiral are exactly the same. They appear different because of the way our eyes perceive them in relation to the contrasting orange and pink stripes. Our eyes contain millions of ‘cones’ which decode light wavelengths to determine colors. When certain colors are combined, our brain is unable to process the information properly.

These ‘bugs’ seem to be moving, but this is actually a static image. Note that whenever you focus on a particular ‘bug,’ it seems to stop moving.

In the Illusion of Change, by Richard Russell of Harvard University, two faces are perceived as male and female. However, rest assured that the both faces are actually versions of the same androgynous face (neither male, nor female). One face was created by increasing the contrast of the androgynous face, while the other face was created by decreasing the contrast. The face with more contrast is perceived as female, while the face with less contrast is perceived as male. The Illusion of Sex Change demonstrates that contrast is an important cue for perceiving the sex of a face, with greater contrast appearing feminine, and lesser contrast appearing masculine.

Do you see a woman with her eyes shut, having her eyelids painted to appear she is staring at us, or the other way round – woman having her eyes opened, but her mascara done in such way, to appear her eyes are shut.

Do you find something unusual in this picture? Can you see any human face in this optical illusion? If not just move away from the screen and try focusing on the center portion.

Headless Gymnast

A Venezuelan gymnast, Katherine Coronel, is performing her routine during the rhythmic gymnastics competition in Colombia. The routine makes her look headless at least for a moment. Find the Man in Coffee Beans

This is bizarre – after you find the guy – it’s so obvious. Once you find him – it’ s embarrassing, and you think, Why didn’t I see him immediately? Is that a Corner House?

First cover the upper half of the picture with your palm, and you’ll automatically assume that the window corner of this building is converx (bulged out). Now try covering the lower half of the photo, and you will see the inner corner of the building (concave this time).

Try and find out whether it is a door or a mirror reflection.

Increase the distance or move away from the screen to see a skull and come little closer to the screen to see a girl sitting in front of the mirror.

Optical illusion of a girl’s face.

Is it just a mountain covered with snow or you can spot something more?

See closely you may see some figures.

Optical illusion of a tunnel vision

An optical illusion is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a perception that does not tally with a physical measurement of the stimulus source. There are three main types: literal optical illusions that create images that are different from the objects that make them, physiological ones that are the effects on the eyes and brain of excessive stimulation of a specific type , and cognitive illusions, the result of unconscious inferences.

3d Street Art also known as 3D Sidewalk Chalk Art is creative 2D Images that look three dimensional graphics or 3D optical illusion from a Particular Viewpoint. Artists like Edgar Mueller, Julian Beever and Kurt Wenner create 3d Street Art that is so incredible.

Batman Illusion on Cement

Waterfall Illusion

Another great optical illusion of a waterfall drawn on concrete. German artist Edgar Mueller creates large scale, three-dimensional art using an unusual canvas – his works are painted on ordinary sections of sidewalks.