<P> This particular hypothesis bridges the gap between the early and late selection theories . Authors integrate the viewpoint of early selection stating that perception is a limited process (i.e. cognitive resources are limited), and that of the late selection theories assuming perception as an automatic process . This view proposes that the level of processing which occurs for any one stimulus is dependent on the current perceptual load . That is, if the current task is attentionally demanding and its processing exhausts all the available resources, little remains available to process other non-target stimuli in the visual field . Alternatively, if processing requires a small amount of attentional resources, perceptual load is low and attention is inescapably directed to the non-target stimuli . </P> <P> The effects of perceptual load on the occurrence of inattentional blindness is demonstrated in a study by Fougnie and Marois . Here, participants were asked to complete a memory task involving either the simple maintenance of verbal stimuli, or the rearrangement of this material, a more cognitively demanding exercise . While subjects were completing the assigned task, an unexpected visual stimulus was presented . Results revealed that unexpected stimuli were more likely to be missed during manipulation of information than in the more simple rehearsal task . </P> <P> In a similar type of study, fMRI recordings were done while subjects took part in either low - demand or high - demand subtraction tasks . While performing these exercises, novel visual distractors were presented . When task demands were low and used a smaller portion of the finite resources, distractors captured attention and sparked visual analysis as shown by brain activation in the primary visual cortex . These results, however, did not hold when perceptual load was high; in this condition, distractors were significantly less often attended to and processed . </P> <P> Thus, higher perceptual load, and therefore more significant use of attentional resources, appears to increase the likelihood of inattentional blindness episodes . </P>

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