Visual perception.

The first 200 words of this essay...

There is likelihood that people who see daggers in the air, as well as people who spot faces in the fire, question the validity of their visual perception. The justification behind this bears the same mark as the reason why people classify magicians as "illusionists" and not "saints". The world of knowledge and experiences that is stored in a healthy brain enable us to distinguish between a genuine phenomena and an illusion - essentially, the former may be inferred from information we know about the world, and the latter somehow contradicts or does not follow the rules we have acquired. This subconscious top-down processing that our brain employs when we come into contact with stimuli around us does at times distort our perception of things, as is shown obviously by the Hermann grid in figure 1 with the squares and dots. How many grey dots are there? If I am not mistaken, there are none at all. However, that is reason speaking, and my eyes tell me otherwise. Why is this so?

The eye is often paralleled to a camera, but is this allusion valid? Firstly, we know from research that the eyes do not see the complete picture