Visual Search for Land Use Objects in Aerial Photographs

Although visual search has been a topic of interest for some time, most search processes have considered simple target symbols in a plain background. The purpose of the current study was to consider more realistic search processes that involved complex targets and backgrounds. A cognitive experiment was conducted in which subjects searched for specific types of land use in aerial photographs. Subjects were presented displays with simple or complex backgrounds that had from one to five primary and secondary objects related to four different types of land use. Primary objects were stores, schools, churches, and farmhouses; secondary objects included parking lots, athletic fields, cemeteries, and agricultural fields. Subjects searched each photograph and determined if the stated target was present or absent. The efficiency of the visual search was measured by reaction time. Reaction times significantly decreased as the number of objects in the photograph increased. The separation of primary and secondary land-use objects significantly increased reaction times. Searches done with complex backgrounds were significantly longer than searches done with simple backgrounds. Visual searches were significantly faster when schools and churches were targets in the photographs and significantly slower when stores and farmhouses were targets.