In this study, we examined the mechanisms that control attention in natural scenes. We asked whether familiarity with the environment makes subjects more sensitive to changes or novel events in the scene. Previous investigation of this issue has been based on viewing 2-D images of simple objects or of natural scenes, a situation that does not accurately reflect the challenges of natural vision. We found that familiarity with the environment significantly increased the time spent fixating regions in the scene where a change had occurred. Together with previous work (Brockmole Henderson, 2005a, 2005b), our results support the hypothesis that we learn the structure of natural scenes over time, and that attention is attracted by deviations from the stored scene representation. Such a mechanism would allow deployment of attention to objects or events that were not explicitly on the current cognitive agenda.