<p>Previous research has explored the effects of retrieval practice on intentional emotional memory; however, its impact on incidentally encoded emotional memories remains unclear. To investigate this question, this study employed a three-phase retrieval practice paradigm, in which participants were asked to evaluate the emotional valence of emotional or neutral images. Behavioral results showed that, compared to restudy, retrieval practice significantly enhanced recognition accuracy for negative items, but significantly reduced recognition of positive items during the final test. Event-Related Potentials (ERP) findings further supported this pattern. A significant ERP retrieval practice effect (reflected by significantly larger ERP amplitude for retrieval-practiced items than restudied ones) was observed over the parietal area between 800 and 1000 ms for negative images. In contrast, a reversed ERP retrieval practice effect (reflected by significantly larger ERP amplitude for restudied items than retrieval-practiced ones) was found for positive images between 300 and 800 ms across frontal, central, and parietal areas during the final test. These findings suggest that, in the context of incidental memory, retrieval practice (compared to restudy) tends to enhance the recognition of negative images while impairing the recognition of positive ones. This emotional modulation of the retrieval practice effect may be influenced by the nature of the encoding task.</p>