stimulus to responses gathered from simultaneously presented stimuli, the responses of the concurrent presented stimuli were less than the sum of the responses gathered when each stimuli was presented alone. This suggests that two stimuli presented together increase neural work load required for attention. This increased neural load creates suppressive processes and causes the stimuli to compete for neural representation in the brain. Proulx and Egeth predicted that brighter objects would bias attention in favor of that object. Another prediction is that larger objects would bias the attention in favor of that object. The experiment was a computer-based visual search task, where participants searched for a target among distractions. The results of the study suggested that when irrelevant stimuli were large or bright, attention was biased towards the irrelevant objects, prioritizing them for cognitive processing. This research shows the effects of Bottom-up (stimulus-driven) processing on biased competition theory. Evidence of Top-down Processes A Top-down process is characterized by a high level of direction of sensory processing by more cognition; Top-down processing is based on pre-existing knowledge when interpreting sensory information. Top-down guidance of attention refers to when the properties of an object (i.e. color, shape) are activated and held in working memory to facilitate the visual search for that object. This controls visual search by guiding attention only to objects that could be the target and avoiding attention on irrelevant objects. Top-down processes are not a complete representation of the object but are coarse, which is why objects similar in color, shape or meaning are often attended to in the process of discriminating irrelevant objects. There is evidence that observers have Top-down control over the locations that will benefit from biased competition in spatial selection visual tasks. Evidence supports that observers can make voluntary decision about which locations are selected or features that capture the attention in a stimulus-driven manner. Neurophysiology studies have showed that the neural mechanisms in Top-down processing are also seen in attention and working memory, suggesting Top-down processes play an important role in those functions as well. Additionally, Top-down processes can modulate Bottom-up processes by suppressing the “pop-out” features of Bottom-up processing from distracting from the visual search. fMRI studies have investigated the Top-down and Bottom-up processes involved in biased competition theory. Results of fMRI suggest that both Bottom-up and Top-down processes work in parallel to bias competition. Multiple studies have shown that stimuli in the