Load theory of attention suggests that insufficient capacity for processing prevents subjects from perceiving irrelevant distractor in high perceptual load tasks (LaVie et al, 2004). The aim of our research was to test the proposed theory in visual search task, sinceLavie et al used choice response task in their research. Participants were asked to search for the oblique line among horizontal or vertical ones, while ignoring irrelevant distractor. The independent variables were target presence, task difficulty (depending on the angle of rotation of the target), distractor (there was either no distractor, or the distractor was oriented in the same direction as the target or in the opposite direction) and set size. The dependent variable was reaction time. Only target-present sets were analyzed. Significant effects of the task difficulty (F(1,11)=118.05, p=.000) and distractor (F(2,22)=17.436, p<.01) factors were obtained, as well as significant interaction of task difficulty and distractor (F(2,22)=17.281, p<.01). Analysis showed that in simple tasks there was no effect of irrelevant distractors. In difficult tasks, reaction times were the shortest when there was no irrelevant distractor and the longest when the distractor was rotated in the opposite direction from that of the target. The obtained results suggest that irrelevant distractor disturbs performance only in high perceptual load task, which is not in line withthe assumptions of the load theory.
