Everyone should watch Robert McNamara’s “The Fog of War.” I particularly liked Lesson # 7 (“Belief and Seeing are both often Wrong”) which deals with confirmation bias. According to McNamara, people see what they want to see. In this particular case, US Navy “saw” torpedoes when there weren’t any, and that led to the escalation of the Vietnam war resulting in horrible consequences. See Lesson # 7 from 05:22 onwards in this video:
and from the beginning to 00:59 in the following video:
Do you see what you only want to see and that which will confirm your prior beliefs?