Discuss the role of bottom up and top down processes in visual perception.

Theories of perception tend to explain how the visual system operates in terms of two kinds of processes: bottom up, data driven ones, that are pre-attentive, and are a consequence of how the nervous system is structured and top down or concept driven processes which  rely on experience, inference and expectations. Apart from the retina, the rest of the visual system has two way connections ( for example the interplay between the lateral geniculate nuclei and the visual cortex), and thus top down processing is an obvious implication of the manner in which the human anatomy is organised….(short extract)