Without knowledge of the different theories of perception, most people are what are know as "direct realists"; they think we perceive things as they are: objects which are independent of us. However, there are many theories of perception. Well know theorists; John Locke, George Berkeley and Karl Pearson all believed in their own, widely diverse or not, theories. John Locke believed in Representational Realism, the belief that objects are not as people perceive them, that was people perceive through their senses are simply representations of an object, and upon reflection a person have ideas thus they have their perception of what the object, to us, is (Locke, 1973, p. 577). George Berkeley believed this was very wrong, and was on of Locke's biggest critics, his theory, Idealism; the belief of "to be is to be perceived" (Berkeley, 1992, p. 77) being vastly different from Locke's. Karl Pearson, on the other hand, had a theory which was also a mixture of both, which was called Phenomenalism. According to this theory, objects exist as sense-perceptions, but also exist when they are not being perceived, as "probable" sense-perceptions (Pearson, 1957, 172). All of these theories have both strengths and weaknesses, and many different people will have diverse views upon which of these theories are correct or incorrect. .
John Locke's theory; Representation Realism, is quite complex, and contains many different steps and different sections to his basic theory. As mentioned before Representational Realism is the belief that objects are not as individuals perceive them; our senses just give us representations from which we draw conclusions as to what the object is in our view. Basically, a person will sense the object, and then reflect upon these sensations. Upon this reflection ideas will be formed. These "ideas" being what is represented of the object to the person. Locke believed there were two forms of ideas; simple ideas and complex ideas.