Feedback should be a key support for optimizing on-the-job learning in clinical medicine. Often, however, feedback fails to live up to its potential to productively direct and shape learning. In this article, two key influences on how and why feedback becomes meaningful are examined: the individual learner's perception of and response to feedback and the learning culture within which feedback is exchanged. Feedback must compete for learners' attention with a range of other learning cues that are available in clinical settings and must survive a learner's judgment of its credibility in order to become influential. These judgments, in turn, occur within a specific context--a distinct learning culture--that both shapes learners' definitions of credibility and facilitates or constrains the exchange of good feedback. By highlighting these important blind spots in the process by which feedback becomes meaningful, concrete and necessary steps toward a robust feedback culture within medical education are revealed.