الفهرس 
الفصل الاوليوجد فقط 14 صفحة متاحة للعرض العام
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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