Recent studies have found that making judgments of learning (JOLs) for verbal materials changes memory itself, a form of reactivity effect on memory. The current study explores the reactivity effect on visual (image) memory and tests the potential role of enhanced learning engagement in this effect. Experiment 1 employed object image pairs as stimuli and observed a positive reactivity effect on memory for visual details. Experiment 2 conceptually replicated this positive reactivity effect using pairs of scene images. Experiment 3 introduced mind wandering (MW) probes to measure participants' attentional state (learning engagement) and observed that making JOLs significantly reduced MW. More importantly, reduced MW mediated the reactivity effect. Lastly, Experiment 4 found that a manipulation that heightened learning motivation decreased the reactivity effect. Overall, the current study provides the first demonstration of the reactivity effect on visual memory, as well as support for the enhanced learning engagement explanation. Practical implications are discussed.