What you see is not what you always get
Lim Tri Santosa
BANDUNG (JP): Everybody is different, so we all may not see things the same way. There are differences in the appearance of measurable aspects of the world, such as size, distance and shape. Sometimes there are hidden things in a picture.
There may be another picture or design inside the original picture. We get used to how things are supposed to be, and sometimes our brains get the clues all wrong.
One optical illusion is the television. The television is just showing you a continuous flow of still pictures, one right after the other. Your eyes, along with your brain, fill in all of the empty spots. Your brain has learned to expect movement, as a result your brain can fill in all of the missing pieces and the pictures on the television appear to you to be actually moving, even though they really aren't!
The fact that we can recover accurate three-dimensional information from a visually ambiguous two-dimensional representation means that some very powerful constraints must be imposed on our interpretations of two-dimensional images. In some cases, illusions take place because the constraints on interpreting an image are ambiguous.
The most common ambiguous figures are of two kinds: figures which alternate as objects, and those which spontaneously change the depth of their position. An example of an alternating figure is "rabbit/duck" (www.sandlotscience.com/Ambiguous). The figure can be seen as either a duck facing left or a rabbit facing right. Once you have realized both aspects, you may flip back and forth between them pretty quickly, but psychologists say that we can never see both exactly at the same time. Even though the image on your eyes remains constant, you never see an odd mixture of the two perceptions.
While part of what we perceive comes through our sense of sight from the object before us, another part always comes from our own mind. It should be understood that both evolution and learning contribute to visual capability. The seeing of objects involves many sources of information beyond those meeting the eye when we look at an object.
Here is an example of when our brain is not synchronized with our eyes. Go to http://surfer1961.terrashare.com/cards02/page20.html, look at the chart and say out loud the color of the words, not the words themselves. Getting confused? Your right brain tries to say the color, but your left brain insists on pronouncing the word.
Seeing generally involves knowledge of the object derived from previous experience, and this experience is not limited to vision but may include the other senses: touch, taste, smell, hearing and perhaps also temperature or pain. Objects have pasts and futures; when we know its past or can guess its future, an object transcends experience and becomes an embodiment of knowledge and expectation. Look at the face of the U.S. president at www.optical-illusions.net; do you believe that it is Bill Clinton and Al Gore?
Our brains put images together because they have learned to expect things, and sometimes the data might get a little confused. We may see an illusion because we know what we are supposed to see, even though part of a picture or design may not be completely there. If our brain and eyes did not function like they do, we would not see illusions like we do. Some people just do not see anything, but with a little help they too can see the illusion.
Artists and scientists over the years have experimented with these rules to produce illusions either by reducing the number of visual cues for interpreting images or by deliberately setting up situations where the rules come into conflict. Look at http://www.optical-illusions.net/ and count carefully the white dots. Hold on. There are black dots.
This array of equally spaced dots is seen as continually changing patterns of rows and squares. We see something of the active organizing power of the visual system while looking at this figure. The few lines are all that is required for the eye -- the brain does the rest from seeking objects and finding them whenever possible. We see the black dots which are not there. Seeing is believing. You will not believe what you see, until your brain synchronize with your eyes and get mixed with your mind. I hope that you will have fun exploring both the scientific and artistic sides of these websites, and see how both artists and scientists have used illusions to reveal the underlying process of the human mind.
Have a nice trip on this illusion journey! To see the phenomenon of optical illusions visit www.eyetricks.com; www.sandlotscience.com; www.optical-illusions.net.