This is the fifth in a series of posts on Visual Processing. The blog post Don't Pay Attention to This is useful background information.
Cover you left eye and look the dot within the circle, with your face roughly a foot from your screen. Move your head towards and away from the screen until the "x" disappears.
Note that when you identify your blind spot, it is not truly blind. It is a continuation of the surrounding grid. You don't perceive a hole in your vision.
Your visual processing system is doing this for you at some point prior to awareness. You can't keep it from happening. This hardwired illusion is an example of Filling In.
Stare at the + in the drawing below. You can keep both eyes open.
You might find that the smudge disappears and fills in pink. This is another example of filling in.
With our peripheral vision we see things that are not there in order to simplify and order our world. This is a special ability of the peripheral visual system. Our central vision cannot do this.
Now, look at the drawing below. When you stare at the model's face, note how clearly you can see her right hand.
Now look straight at the hand. There is very little there. But when you look at her face, the arm is there. The hand is obvious. You have drawn this inside your mind- and are hardwired to do so. You are an active participant in the creation of objects within the drawing- and everyday in your perception of the world around you.
In conclusion, the peripheral visual system does something that the central visual system cannot. It is hardwired to create illusions. It imagines, draws objects, creates and eliminates. Unchanging stimuli fade away. Formed objects are created.
Your central visual system does not do these things. It is precise- but not imaginative.
We can take advantage of this when we draw. Portions of a drawing can be drawn using the language of the central visual system- high detail, clear delineation of form, and high contrast. When we do this, the viewer will feel a force attracting their central focus to areas off high detail and high contrast. Other portions can be drawn in the language of the peripheral visual system- less specific delineation of form, low detail, low contrast. As in the drawing above, formed illusions of details such as hands and feet can be achieved if the correct hints are drawn and the viewer's eyes are directed to a different location.
Lack of universal detail engages the imagination of the viewer. The peripheral visual system is not exact- but it is creative and lively. The drawing that excites the peripheral visual system is no longer a monologue. It becomes a conversation. The viewer participates, contributes, and feels connection.