This paper deals with the preattentive processing of banner advertisements under competitive interference conditions. In the absence of competitive interference, our experimental results were consistent with hemispheric lateralization: pictorial banner ads were evaluated more positively when positioned on the left (vs. right) side of a webpage, whereas the opposite pattern was observed for verbal banner ads. In contrast, this interaction disappeared in the presence of competitive interference. Specifically, verbal banner ads received more positive evaluations than pictorial ads when they featured products from the same category. In addition, banner ads were more liked when positioned on the left (vs. right) side when they were of the same ad modality.