Background: Previous research shows that critical constructive feedback, that scaffolds students to improve on tasks, often remains untapped. The paper's aim is to illuminate at what stages students provided with such feedback drop out of feedback processing. Methods: In our model, students can drop out at any of five stages of feedback processing: (1) noticing, (2) decoding, (3) making sense, (4) acting upon, and (5) using feedback to make progress. Eye-tracking was used to measure noticing and decoding of feedback. Behavioral data-logging tracked students' use of feedback and potential progress. Three feedback signaling conditions were experimentally compared: a pedagogical agent, an animated arrow, and no signaling (control condition). Findings: Students dropped out at each stage and few made it past the final stage. The agent condition led to significantly less feedback neglect at the two first stages, suggesting that students who are not initially inclined to notice and read feedback text can be influenced into doing so. Contribution: The study provides a model and method to build more fine-grained knowledge of students' (non)processing of feedback. More knowledge on at what stages students drop out and why can inform methods to counteract drop out and scaffold more productive and fruitful responses.