Visual Illusion- Pareidolia

July 27, 2014

Pareidolia is an illusion, a visual phenomenon that occurs when a vague, undefiled stimulus is perceived as being distinct. It is a form of apophenia, which is the idea of observing a pattern in meaningless information or data. Leonardo da Vinci once said that pareidolia was a tool for painters to provoke viewers to interpret a simple set of colors and stains into something more, such as landscapes and complex expressions. Recently, a chicken nugget that resembled US President George Washington had earned more than $8,100 on eBay.

You might observe a resemblance of a face in the images below. The first one is an image taken in 1976 by the Viking Orbiter of a rock formation having somewhat of a resemblance to a human face. Newer and clearer images of the same Cydonia region in Mars show a simple set of lines that had previously been thought of as a human face. The second image is of a set of clouds that also show features that coincide with that of a face.

Dr. Nouchine Hadjikhani of Harvard University stated that humans are “prewired” to detect faces from birth, and that “If you take a baby just after a few minutes of life, he will direct his attention toward something that has the general features of a face versus something that has the same elements but in a random order.” Sophie Scott, a neuroscientist in University College London, also expressed that pareidolias can be a product of people’s expectations. People also strongly believe that pareidolias are a supernatural phenomena.

Whether they be pure coincidence or the work of a supernatural force, they are extremely interesting to observe and understand. Their use in artwork especially causes people to dig deeper than just the simple shapes and lines, allowing them to come up with their own depictions of the work.

pareidolia pareidolia3
Sources:
http://www.bbc.com/news/magazine-22686500
http://www.michaelbach.de/ot/fcs_face_on_mars/index.html
http://en.wikipedia.org/wiki/Pareidolia


The Ebbinghaus Illusion

July 25, 2014

The Ebbinghaus Illusion is a famous illusion in which the size of dots appears to be different due to the size of the objects around them.

Ebbinghaus

The left hand dot seems to be smaller than the right hand dot, but they are, as is expected in a visual illusion, the same size.

This property of the brain, to adjust the size of objects in relation to their surroundings, can be a very useful one. When looking at a group of large objects, something that is relatively small should not be perceived as important. Contrastingly, when viewing a cluster of small objects, something relatively bigger should be viewed as more significant and important. Even if the relatively smaller and larger objects are the same, their surroundings decrease or increase their importance respectively. The orange dot on the left hand side is not as important as the same sized orange dot on the right hand side because one is enveloped by bigger dots while the other is surrounded by smaller dots. Perspective, once again, becomes the determining factor when viewing this image.

However, the size of the surrounding objects is only half the story. The distance between the central dot and the other dots is also a major factor in the perceived size difference. When the surrounding dots are farther away from the central dot, the orange dot will appear smaller because there is more space between it and the other dots. Contrarily, when the blue dots are close to the central, orange dot, the orange dot appears bigger. These two factors together make the Ebbinghaus Illusion very deceptive.

A determining neurological factor in the deceptive ability of this illusion to an individual is the size of their primary visual cortex, or V1, a region in the back of the brain that processes the visual information received from the eyes. The size of V1 is extremely variable from person to person. People can have a V1 three times the size of someone else’s. This leads to different perceptions of the Ebbinghaus illusion.

The Ebbinghaus Illusion correctly portrays the “flaw” in our visual system which leads to differential perceptive ability. Without this mechanism, we would focus just as much on the smaller objects in a large group of objects as the bigger ones. With this mechanism, we can effectively prioritize which objects need to be viewed in relation to others. Bigger objects in a group of small objects receive more attention while smaller objects in a group of big objects receive less attention.

Interestingly, children under 10, who have lower context-sensitivity (differential perception ability) and thus are not deceived by the Ebbinghaus Illusion. Don’t we all wish we could just be kids again!

Cheers,

Dhruv


Visual Illusions

July 25, 2014

Hello everyone!

I found a really interesting visual illusion that I would like to share.Screen shot 2014-07-25 at 1.52.34 PM

 

Above you can see two faces. Our brains are very used to perceiving faces and recognizing people. This illusion was created by psychologist Richard Russell from the University of Gettysburg. According to him, the left face is perceived as being a female face, while the right face is perceived as being a male face. Can you see it? The weird thing is that the two faces are actually identical! It is the same androgynous face. The only difference between the two faces is that the contrast between the eyes, lips and the rest of the face on the left is greater. The contrast on the left was increased while the contrast on the right was decreased. This creates the illusion that we are looking at a female on the left and a male on the right. This optical illusion demonstrates that impact of contrast on our vision is very important in perceiving the sex of a face. We unconsciously use contrast in order to differentiate between men and women!

I found this information very interesting. According to Russell, this optical illusion explains why cosmetics make women look more feminine. Lipsticks and eyeliners magnify the contrast between the eyes and lips and the rest of the face. The cosmetics industry is huge and it has developed because of this aspect of our visual system. Cosmetics exaggerate this contrast in order to make a female face appear more “feminine”. It is interesting that two identical faces with such a small difference as contrast can be perceived as so widely different by our brain. According to Russell, beauty is actually not skin-deep, it goes as far as the brain!