Visual search is any task where the observer has to find some desired object, or target, in a field of multiple nontarget distractor objects. We perform hundreds of visual searches each day: searching for a shirt in our closet, finding our car keys on the nightstand, or looking for a friend in a crowd of strangers. There are many socially important visual search tasks, such as searching for threats in X-ray scans of baggage, finding potential tumors in mammograms, or looking for airplane wreckage in satellite photographs. In classic laboratory search tasks, the observer sees a search array of items (e.g., colored rectangles) and must report whether or not a specified target (e.g., “green vertical rectangle”) is present. These stimuli are intended as an easily ...