The pop-out effect (also known as pop-out phenomenon) occurs when a visual stimulus that is comprised of differing components has mostly similar looking objects but one differing object that ‘pops-out’ or stands out very noticeably from the other objects in the visual field. When looking at a visual field a unique stimulus can be located much faster than stimuli that is similar. A red circle that is on a page with blue circles will pop-out and be automatically seen and not require searching. Knowledge of the pop-out effect is used to make advertisements and road signs more effective by using contrasting stimuli in a visual field.