These sources explore the psychological and neurological distinction between surface familiarity and genuine mastery in learning. While repeated exposure builds processing fluency and increases subjective feelings of truth or liking, the texts argue that this "ease" often creates a measurement illusion that masks poor long-term retention. True learning—defined by durable recall, flexible transfer, and the ability to explain concepts—requires "desirable difficulties" like spaced practice, interleaving, and active retrieval. Empirical evidence across motor, language, and conceptual domains suggests that familiarity is a necessary initial substrate for intuition but is insufficient for complex problem-solving. Ultimately, the research cautions that mistaking recognition for knowledge leads to fragile expertise, whereas deep understanding demands structural integration and error-correction beyond mere repetition.