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المستخلص When we attempt to succeed in a goal-directed task, we usually attend to those aspects of the environment that are most important at the expense of those that are not. This attempt to attend to some sensory stimuli to the exclusion of others is accomplished by a cognitive mechanism commonly called selective attention. Cognitive psychologists have long sought to understand this operation. One of the key milestones toward this understanding is determining when the selection of relevant information, and hence the filtering of irrelevant information, occurs during information processing between the stimulus event and the response that is made, Theories have tended to center around the notion that relevant information is selected either ‘early’ (Broadbent,1958;Treisman,1969) or ‘late’ (Deutch&Deutch,1963:1967; Norman,1968; Duncan,1980) during the information processing stream. According to Lavie and her colleagues (1995,2001, 2004,2005), the locus of selection-early versus late-depends on perceptual load, the total amount of potentially task-relevant information that is available or the effort required to process the information. Lavie suggested that when perceptual load is high, ,our limited processing capacity is exhausted and there is no attentional resource available to process irrelevant distractors. As a result, there are reduced interference effects from irrelevant distractors under high load and selection occurs earlier .However, in low perceptual load situations, spare capacity left over can be used to process irrelevant distractors. As a result, interference effects from irrelevant |