Seeing is basically a biological process involving the light from the surrounding reaching the eye's retina, where it is transmitted to the brain as electric impulses via the optic nerves. The brain then translate the impulses into a visual image that we understand as visual image. The choice of what you choose to look at is important; because the eye cannot see from all direction, it cannot focus on everything. Thus, a "viewer's personal motivation in the act of noticing" comes into play (Jamieson, 2007, p.15). This meant that there is a decision being made in deciding what to focus our attention to when we see. Although that is case, it is worth noting that our eyes are naturally attracted to change in the visual, either from color changes, or movement (Petterson, 2002, p.212-214). From a biological point of view, this could evolve from surviving in the nature as it helps notify danger and spotting preys.
On the other hand, perception is the interpretation of the world around us. To be able to do that, the 5 senses, not just sight, are combined to make sense of the surrounding. This happens in the brain. The understanding or making sense of the information gathered from our surroundings are conceived from various factors, such as psychological factor, pre-existent knowledge, past experience and culture. In the words of Jamieson (2007, p.21), perception "imposes a particular kind of order, predetermined by the templates which it cares to utilise", the templates mentioned being factors such as the culture a person lives in, pre-existent knowledge, and etc.
Look at the two image below. Can you make sense of what you are seeing?
Most likely, you will be able to read the two words. That is because you are able to perceive them. From your eye, the visual of a collection of black shapes amidst white is transmitted to the brain.Your brain has the knowledge of literacy, specifically the English language. For someone who has never encounter Roman letters, they could make no sense of it. It would be a collection of black shapes. Because everyone has their own unique experiences that made up the various "templates" that the brain uses to perceive, no two person will perceive the same thing identically (John Medina, 2008, p.205-206).
As a conclusion, you may be seeing (i.e. light is entering your eyes, and electrical impulses inputted into the brain), but you may not be perceiving what you are seeing. Perception happens inside the brain, while seeing involve the visible light and the retina of the eyes. A person who daydreams will see what is in front of him, but will not make sense of what he is seeing. The brain is engaged, perceiving a different visual image in his mind.
References:
Jamieson, H. (2007). The perceptual connection. Visual communication: More than meets the
eye . Retrieved August 16, 2012 from Universiti Brunei Darussalam Ebrary Books Website
Petterson, R. (2002). Cognition. Information design: An introduction. Retrieved August 16, 2012 from Universiti Brunei Darussalam Ebrary Books
Website
Medina, J. (2008). Sensory Integration: Rule #9 Stimulate more of the senses. Brain rules: 12 principles for surviving and thriving at work, home and
school. Seattle: Pear Press
