Construction

    Claims could be made that an understanding of vision leads to a complete understanding of how the eye functions and creates images. Any such claims would be false. Scientists are coming to the realization that more takes place in our heads than simply piecing a picture together. As studies into the exact process of construction dig deeper, experts also are realizing that vision is a process more complex than ever anticipated and so complex that it may never be fully understood.

    Our eyes provide clues such as shape, color, size, texture, depth and movement that allow us to piece together a complete picture and thus understand what we are seeing. But sometimes our perception of an image is not entirely correct. Further in this section you will find examples of when we both under-interpret and over-interpret an image. You may come to the conclusion that you can not trust your vision as much as you would like to. Although, you may come the conclusion you need to realize and accept what your vision does and does not do for you.

Piecing Together a Picture

    How long does it take you to realize what exactly you are looking at? Do you step into a room and think to yourself, "There is a table. There is an oven. There is a sink and there is a refrigerator"? Most of us immediately step into such a room and conclude that we are standing in a kitchen. Of course, we sometimes are presented with an object we have never seen before and could ponder over its use forever. In most cases we are able to quickly piece together a series of visual clues to determine what exactly we are seeing. As we age we teach ourselves to recognize object more quickly and often do not appreciate what a complex process it can be.

    This process of construction happens on both a very broad and very specific scale. The example of recognizing you are in a kitchen is the process of recognizing entire objects and realizing their relation in a typical room we call a kitchen. But we also construct using visual clues on a very specific basis, such as recognizing a specific object or even the existence of an object. Our brains sometimes have to piece together as little information as a line or curve to decipher something like a letter of the alphabet. You could spend great amount of time every day if you had to slowly piece together every line, curve, shadow and color of every object in every place you visited.

	Test Your Ability to Construct: Test yourself with this interactive puzzle to see how well you construct and image. Once you begin, a series of image fragments to appear in sequence. Your goal is to identify what the image is of. Once the sequence has run you will have the option of replaying it or seeing the answer. See how long it takes for you to get the right answer, or if you get the right answer at all. Have a friend try and it and see how well you did compared to him or her. This puzzle is an example of how our construction process works, but on a much slower and restricted level. When we are presented with an image we take in each part and put it together to come to a conclusion. In this puzzle you are forced to take in each part slowly and without the help of the other parts. Good Luck!

Dimension

    You probably do not realize how much work you do to utilize the images your eyes create for you. We often are impressed and excited when we put on a pair of 3D glasses and see a picture on a piece of paper take on depth. Why are we so impressed to see a two-dimensional image suddenly make itself appear three-dimensional? Our eyes do the very same thing every time we open them! Every image we see is projected onto the retina where it is formed as a two-dimensional picture on a curved surface, the back of the eye. Binocular vision turns the two-dimensional image on the retina into the three dimensions that we can see.

	Prove it to yourself: Does this image appear to be two dimensional or three dimensional? Close your eyes and place your hand on the monitor. Does this image feel two dimensional or three dimensional? Most people respond differently to these two questions. Our sense of sight has told us that this is a tub has height, width and depth but our sense of touch can only decipher height and width. How can this tub be both two dimensional or three dimensional at the same time? Check one more time; maybe your eyes aren't telling the truth. Look at this image upside down or from the side. Can you find a position where the tub loses it's third dimension? It is not likely you ever will. The brain is so used to interpreting two-dimensional images as three dimensional that it is now practically impossible to see this tub without depth.

Phenomenal Sense and Relative Sense

    Has the thought every crossed your mind that maybe what you see is not what is really there? This concept has been dealt with many times in movies such as The Matrix and Star Wars. In The Matrix actor Keanu Reeves' character Neo discovers the world he lives in is purely the creation of another controlling species that is pumping a fictitious experience into his brain. Neo finds in reality that his body merely sits in a chair while he is able to "live" in another world created entirely in his mind. What Neo was experiencing was not actually there, he constructed it. In the movie Star Wars the characters use messaging devices, holoprojectors, that project images into thin air. The characters are able to see another character but if they had attempted to touch the other person they would have been disappointed to find nothing there to touch. Once again, this image has been entirely constructed using various visual clues.

Philosophers have a name for this type of perception. When you construct an object that is not necessarily there you are said to be seeing that object in the phenomenal sense. Philosophers use the word phenomenal to mean an object that appears real to the mind, regardless of whether its underlying existence is proved or its nature understood. In a very obvious example, the phenomenal sense would be used when a delirious person wandering the desert might see an oasis when in fact there would be no such place perceived by others. However do not take your phenomenal sense for granted. This type of visual sense is not only utilized by those who are delirious. When you saw the third dimension of the tub you were utilizing the phenomenal sense because we can not prove the existence of depth.

    Philosophers also have a name for the sense in which we perceive things that actually exist. This sense is called the relative sense. Objects that we construct that can be proven to exist are seen in our relative sense. If the person in the desert were suddenly only able to utilize his relative sense the desert oasis would disappear because it does not actually exist. Both of these types of visual sense are examples of how your brain constructs images using visual clues, whether or not the object actually exists. Be on the look-out for examples of using your phenomenal and relatives senses both on this site and in your everyday experiences.

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