Guided Search is a model of visual attention that explains how we find our intended target when looking in a crowded visual field. Let's say we are at a big sporting event and we get separated from our friend. How do we ever find him in a sea of distracting look-alikes?
According to guided search theory, we first process multiple basic features such as color, shape, and motion simultaneously across a large field. We then look for one specific element or combination of basic features at a time in a smaller area of the visual field. So we might first scan the sporting event crowd for the color and pattern of our friend's shirt and then focus on the most promising spots in the crowd to find his face. Thus, information from the early stage of processing is used to guide attention in the later stage and make our visual search more efficient.