Biased competition theory advocates the idea that each object in the visual field competes for cortical representation and cognitive processing. This theory suggests that the process of visual processing can be biased by other mental processes such as bottom-up and top-down systems which prioritize certain features of an object or whole items for attention and further processing. Biased competition theory is, simply stated, the competition of objects for processing. This competition can be biased, often toward the object that is currently attended in the visual field, or alternatively toward the object most relevant to behavior. History Research into the subject of attentional mechanisms in regard to visual perception was undertaken as an attempt to better understand the functional principles and potential constraints surrounding visual perception Visual search tasks are commonly used by experimenters to aid the exploration of visual perception. The classical view of visual attention suggests that there are two basic principles: the pre-attentive stage and the attentive stage. In the pre-attentive stage, an individual has an unlimited capacity for perception which is capable of processing information from the entire visual field concurrently. During the attentive stage, the processing of visual information corresponding to local spatial areas takes place. This classical view of visual attention suggests that there is no competition within the visual field. Within this theory an individual is assumed to be capable of processing all information provided concurrently. Until recently it was still thought that individuals had a pre-attentive stage. This is no longer the case, research has now suggested that the pre-attentive stage is now limited in its capacity. The attentive stage of being able to process important information has now transformed into what is known as selectivity. The classical view of attention has built the ground work for the recent emergence of two new principles to benefit the understanding of visual attention. The first of these relates to the limited capacity of information processing. This suggests that at any given time, only a small amount of information can actually be retained and used to control behaviour. The principle of selectivity incorporates the notion that a person has the ability to filter out unwanted information. Koch and Ullman proposed that attentive selection could be implemented by competitive "winner-takes-all" networks. Robert Desimone and John Duncan expanded on this idea. They proposed that at some point between the visual input of objects and the response to objects