Are both green lines the same length?
If you perceive that a bad guy is pointing a gun at you, does the fact that you are wrong make him any less dead? If someone perceives your testimony as a lie, does the fact that they are wrong still convict the bad guy? Perception matters and can often be modified with knowledge.

How should a police officer view himself in comparison to everyone else? Lt. Col. Dave Grossman wrote on of the most profound explanantions I have ever read. You can find it here: http://www.killology.com/sheep_dog.htm

Have you heard: "If you claim you did not see it then you must be a liar, it was right in front of you." Do you question whether something is wrong with you? The explanation can be found here: http://www.theinvisiblegorilla.com/videos.html