Within attention studies, Lavie's load theory (Lavie & Tsal, 1994; Lavie, Hirst, de Fockert, & Viding, 2004) presented an account that could settle the question whether attention selects stimuli to be processed at an early or late stage of cognitive processing. This theory relied on the concepts of "perceptual load" and "attentional capacity", proposing that attentional resources are automatically allocated to stimuli, but when the perceptual load of the stimuli exceeds person's capacity, task-irrelevant stimuli will not be processed. Previous studies have shown that attention-demanding tasks get improvement with practice, but there has been no clear evidence of how this improvement relates to "perceptual load" (within Load theory framework). The present study used one of the experimental paradigms used in studies motivated by this theory to investigate the effect of practice on perceptual load. Participants were asked to practice a visual search task, and ignore an irrelevant distractor, for five sessions. In the first session, results replicated previous studies showing that irrelevant distractors were processed only under low perceptual load. With practice, distractors began to be processed under high-load too, and less processed under the low-load condition. Results are interpreted as practice modulating the effective perceptual load of stimuli under high load conditions (perceptual load diminishes, therefore attentional resources are allocated to the irrelevant distractor that was not originally processed), and practice increasing the effectiveness of active inhibition of irrelevant distractors under the low perceptual load.