Processing- All in Your Head

Our model of vision began with the eyes.  When they are functioning correctly and provide clear, efficient input processing begins within the brain.  The brain utilizes that input and organizes it.  The brain creates a means for us to understand that information.  Without this step there would be a massive amount of information but no effective way to access or use it, similar to the internet before Google.

As an example of processing, what is the difference between the following two images?

Obviously both are fruit bowls, but one is a photo and the other is a painting.  They are from two different perspectives, one from above and one from the side.  You immediately realized these differences but notice they are both filled with similar colors and shapes, both include grapes and pears.  While both are two dimensional objects they even provide some sense of depth with shadowing and detail.  Nearly identical pieces of data were sent from your eyes to the brain. So the obvious question is, how did you know one existed in real life and the other was a representation?

It’s a fantastic question and the only honest answer is, we don’t exactly know for sure.

What we do know: Vision is more than simply what we see. The brain has an area that is the primary vision center; it is called the occipital cortex.  This is where our conscious vision takes place.  However the information from our eyes does not go straight to the occipital cortex, create an image there and then we can.  While a very large portion of it goes to the occipital cortex and provides the images we see, some information goes directly to other areas of the brain.  These areas provide for other functions.  For instance, if we each were to close our eyes right now we could still find our way out of the room, perhaps with a bit of stumbling; yet none of us studied the room specifically to develop one.

You may have heard of individuals with ‘blindsight”, they have suffered a stroke in the occipital cortex.  They no longer have what we think of as our conscious vision and if you ask them, they will say they are blind.  However if you put these individuals in a room and force them to trust their instincts they can walk across the room without bumping into a chair or table.  The information from the eyes still gets to the area which provides the layout and if they trust their instincts they can navigate through the room.

Both the pictures above and the blindsight are excellent real life examples of processing but they cannot be evaluated in the general population.

In an office setting we can test for several specific processes

• Can you fill in shapes when parts are missing?

• Can you pick out a specific shape when it is surrounded by other similar shapes?

• Can you discern the black letters from a white background?

• And others.
   

If deficiencies are present within procession we can use methods to improve these processes.  The brain can learn and be trained to see things differently.

“Dodge”

William Dodge Perry, OD