It's a difference in one's conscious reasoning rather than in one's actions, so my only direct examples are my own and intransmissible. You can infer it from "who you are in the dark" cases where you happened to observe someone who believed they would be unobserved and still did the altruistic thing, but obv. that requires being confident they weren't just playing the game one level higher than you.
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.