The idea of this presentation is to try and make us a little more cognizant of how much of our perceptions are illusion, and to encourage us to bear that in mind a bit more when our considerations of our selves and our world.

Vision and color perception are the primary sensory proxy for understanding consciousness, and like other senses and consciousness itself, it subjects us to many illusions.  I'd like to talk about three different levels on which illusions affect our understanding of the world:

1. Illusions in which we can easily recognize how reality differs from our perceptions
2. Illusions where one is aware of the the difference between the illusion and reality (i.e. we don't recognize it as an illusion at all); and
3. Illusions that we understand intellectually, but which we cannot prevent from continuing to fall victim to in some way

Let's start by considering what we refer to as  optical illusions.  With the typical optical illusion, it is readily explained to us how our perceptions differ from reality.  E.g. by fixing our gaze on specific portions of the imagine, it only takes us a few moments to figure out that nothing is actually moving in the Rotating Snake illusion or the Blue and Yellow Dots illusion   Note that recognizing the non-moving reality of these pictures does not stop us from perceiving motion when we look at them, but with the limited times we are exposed to them, when we see them in the future we immediately think of them as illusions.

This is somewhat different from more persistent illusions such colors being properties of objects in the external world (i.e. external to our brains).  We may intellectually recognize that while these objects have shape and chemical properties, colors are something are invented entirely within our brains, and are a code the brain uses to represent the objects, not qualities of the object itself.  But even so, I submit that we cannot keep assuming, at some level of consciousness, that the fire engine is red.

We'll return to this later, but for a moment let's consider how perceptions like this led to misperceptions of how vision works.  For example, let's consider the belief that visual perception works via tiny emmissions from the eyes.

This "extramission theory" of vision dates back at least as far as Greek philosopher Plato (427-347 B.C.), who spoke of a "fire" that emanated from the eye during vision, which "coalesces with the daylight ... and causes the sensation we call seeing."  Later, Greek mathematician Euclid (circa 300 BC) described "rays proceeding from the eye" during vision."   ("50 Great Myths of Popular Psychology," p34)

Now you may think that this type of thinking about vision strictly predates modern optics, and that eyes emitting rays now exists only in comic books.  But the belief that we see by emitting something from our eyes remains quite common.  57% of elementary school children say that something comes out of our eyes when we see.  So something about this idea seems to be strangely intuitive.  And while this belief declines with age, surveys have found that 30% of more of adults also claim the belief when asked if the eye emits rays or particles that enable it to ee objects.  (Ibid)

Beliefs about visual perception that have been soundly debunked by science are surprisingly common.  E.g. when I googled "primary colors," one of the top results I got was this definition from About.com.