Visual selective attention is a brain function that controls the processing of retinal input based on whether it is relevant or important. It selects particular representations to enter perceptual awareness and therefore guide behaviour. Through this process, less relevant information is suppressed. Visual selective attention is an essential factor in producing efficient, goal directed behaviour. Our processing resources as humans are limited, and it is therefore crucial to be able to distinguish important information in an environment which produces vast amounts of sensory input every second. In order to guide behaviour, only a small amount of that sensory input can be allowed to reach perceptual awareness. Therefore, to operate efficiently, this goal directed behaviour is mediated by visual selective attention. This allows us to selectively focus on and attend to specific information that is important or relevant to the situation or context we are in. This information then gains access to further processing, where it aids goal directed behaviour through enhancing the representation of salient and relevant stimuli, and suppressing distracting stimuli which are less relevant. The processing of distracting stimuli may interfere with the implementation of the intended behaviour. Visual selective attention is the processes that is involved in detecting one source of sensory information over another, therefore ignoring or disregarding other sources available in the present environment. It requires many underlying cognitive processes, including detection of important sensory/perceptual information, the ability to inhibit information that is irrelevant to the task, and the ability to shift attention from one feature or location to another. In neurodegenerative diseases such as Alzheimer's disease, dementia with Lewy bodies, and Parkinson's disease, areas such as the basal ganglia, cerebral cortex, locus coeruleus, temporal, parietal and frontal lobes, and the limbic system, especially the hippocampus and amygdala, are impaired. These areas are involved in executive functions, including memory and attention, especially visual selective attention, and therefore deficits in these abilities arise. This can result in an individual's inability to efficiently ignore distractor information when attending to specific stimuli. Visual selective attention and normal aging Loss in the ability to efficiently ignore distractor information increases with age. This is due to age-related deficits in selective attention and working memory, particularly with regard to a reduced ability to inhibit distracting sensory information. In a study by Kotary and Hoyer, adult age differences were examined in terms of the effects of distractor interference on visual search. Distractors