Perceptual load and visuocortical processing: Event-related potentials reveal sensory-level selection

Behavioral evidence suggests that the processing of parafoveal stimuli decr eases as the perceptual demands of a task at fixation increase. However, it remains unclear whether or not this effect of perceptual load occurs durin g initial sensory-level processing at early stages of visucortical analysis . Using event-related potential measures, we found that increasing the perc eptual load of foveal targets led to a significant decrease in the sensory- evoked response to parafoveal stimuli. Moreover, these effects were observe d using two different operational definitions of perceptual load. This resu lt indicates that perceptual load affects the flow of information during th e initial stages of visuocortical processing.