Visual Illusion


How many times have you found your mind being blown away by visual illusions? They may include illusions in images you see or movements of objects in space. 

Illusory image

You are at a fixed point and you see the stationary object move. When you move it moves also. Or maybe you look at a fixed image you see it as if it is in motion.

When it comes to visual illusions, it's not imagination, our brains perceive optical illusions as real motion. Your eyes mistakenly see a flying bat as if it's a flying bird because of the shadows in the branches of the trees.

Visual Illusions are perceptual distortions. The angle of view may distort important visual information, therefore, causing an illusion.

Visual Illusions

An optical illusion can be thought of as an unexpected experience whose details contradict that of the environment when analyzed by other means.

There are many forms of visual illusions. Those comprising geometry or angles, those involving brightness, contrast, or color, those involving size fixedness, unusual images, mirages, those involving motion, and so on.

Illusory image

However visual illusions are not harmful to your eyes, they are known to threaten airplane pilots and endanger astronauts.

"The saying of seeing is believing is like putting eggs in the wrong basket sometimes seeing is deceiving" (Coren and Girgus, 1978)


Have you seen something like a fire rising in the middle of an open land or ground space? When the weather is hot and the sun is scorching. This is an optical illusion known as a mirage.


The effect is sometimes seen at sea, in the desert, or over a hot road or sidewalk may look like a pool of water or a mirror in which far objects are seen upside down, and that is caused by the bending or reflection of rays of light by a layer of hot air of differing density.

Mirage results from the total Internal Reflection of light by the numerous layers of air. Mirage is an optical sensation that creates an illusion of the presence of water and is a result of the refraction of light from an incomplete medium.

Most of the time waves of light from the sun move straight through the atmosphere to your eye. However, light moves at different velocities via hot air and cold air.

Therefore, mirages happen when the surface is very hot and the air is cool. The hot surface or ground heats a layer of air just above the surface. When the light moves through the cold air and into the layer of hot air it is bent, hence causing visual illusions.

Mirages in the desert are known to attract people with the illusory effect, guess that they are moving near the water bodies, while they are in the middle of nowhere, moving towards the vastness.

Geometrical Illusions

Have you encountered drawing which shows geometrical Illusions, they cause a disagreement between what you see and what you can measure with a ruler.

Researchers found that illusions are virtually full stability when their portions are illustrated to each eye singly, indicating that distortions are in the brain and not in the eye.

Also, Scientists suggest that geometrical illusions influence eye movements as well as perception.

Geometrical illusion

Autokinetic Effect.

When we look at the light, our eyes seem motionless, but they move about randomly over a tiny area. As a result, the image moves slightly over the retina.

The autokinetic Effect is the trend for stationary light viewed against the darkness to look as if it's moving. The light seems to fall and drift through space.

Eye movements do play part in visual Illusions. Eye movement does produce autokinetic motion of light because the brain fails to keep track of eye movements unless the light has a fixed relationship to other objects.

In other meaning is that this hypothesis is that the brain makes more errors in registering eye movements when the light is viewed without a patterned background.

The autokinetic Effect is dangerous for aviators. Planes flying at night have collided because pilots saw the autokinetic movement of the wings of another plane.

Practical ways to reduce the autokinetic effects.

  • Replacing single lights with a collection of several lights or clusters.
  • Have the light source flash or blink. Researchers showed that autokinetic motion is greatly reduced for lights flashing between 4 and 10 times per second.

No one understands why the clusters and flashes work, but the results are of practical value.

Artists do like to create optical illusions in their paintings. An image in which its elements and details merge to form an illusion. Images with physical similarities but we see them differently.

An image that changes orientation gets so much mileage to provide ambiguous information and let our minds do the rest.

We get fascinated by each artistic illustration, from Da Vinci's anamorphic to modern-day paintings of artists like Jonty Hurwitz and computer-generated tricks of the eye. Also, artistic visual illusions give us a chance to learn cognitive science, how we see and perceive, and how our minds interpret visual messages taken from the eye.

Drawing from the usefulness of illusions we experience.

  • Though illusions are distortions of human eyes' visual reality since they are misperceptions or defective percepts. Machines will be designed to be free from this kind of defect and that's how we are humans and not machines.
  • Illusions display unique characteristics of human neural pathways. The illusions are therefore natural to us. We can correct optical illusions using devices but still, our neural system falls short of perfection.
  •  The processes that generate optical illusions operate unconsciously. Kihlstrom (1987) and Kihlstrom et al. (1992) concur that PDP-CNN models of cognition have an unconscious-centric orientation.
  • We are fascinated by Illusions when used artistically to portray an abreast and contrasting idea or message therefore the firm basis for the virtual reality industry. Gonzalez-Franco and Lanier, (2017).
  • Visual illusions are used by scientists to study Dyslexia and Autism Spectrum Disorder.
  • Psychologists use visual illusions to study human perceptual systems.
  • Visual illusions make us happy and entertained.

Visual Illusions play a great role in our perceptions. The way we view reality and how we respond to reality. Our world is real but our views of it are distorted most of the time and that's our nature.

Sometimes we benefit from the illusions and sometimes we get things wrong due to our nature and limitations in our perceptual systems.


Coren, S., & Girgus, J. S. (1978). Seeing is deceiving: The psychology of visual illusions. Routledge; 1st edition (February 16, 2022) 

Visual Illusion, ScienceDirect.

Gori S, Molteni M and Facoetti A (2016) Visual Illusions: An Interesting Tool to Investigate Developmental Dyslexia and Autism Spectrum Disorder. Front. Hum. Neurosci. 10:175. DOI: 10.3389/fnhum.2016.00175

Sánchez-Tena, M. Á., Alvarez-Peregrina, C., Valbuena-Iglesias, M. C., & Palomera, P. R. (2018). Optical Illusions and Spatial Disorientation in Aviation Pilots. Journal of medical systems, 42(5), 79.


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