Manipulated images can have serious and persistent ramifications across many domains: They have undermined trust in political campaigns, incited fear and violence, and fostered dangerous global movements. Despite growing concern about the power of manipulated images to influence people’s beliefs and behavior, few studies have examined whether people can detect manipulations and the psychological processes underpinning this task. We asked 5,291 older adults, 5,291 middle-aged adults, and 5,291 young adults to detect and locate manipulations within images of real-world scenes. To determine whether a simple intervention could improve people’s ability to detect manipulations, some participants viewed a short video which described the five common manipulation techniques used in the present study. Overall, participants demonstrated a limited ability to distinguish between original and manipulated images. Older adults were less accurate in detecting and locating manipulations than younger and middle-aged adults, and the effect of age varied by manipulation type. The video intervention improved performance marginally. Participants were often overconfident in their decisions, despite having limited ability to detect manipulations. Older adults were more likely than younger and middle-aged adults to report checking for shadow/lighting inconsistencies, a strategy that was not associated with improved discriminability, and less likely to report using other strategies (e.g., photometric inconsistencies) that were associated with improved discriminability. Differences in strategy use might help to account for the age differences in accuracy. Further research is needed to advance our understanding of the psychological mechanisms underlying image manipulation detection and the myriad factors that may enhance or impair performance.