Although not paranormal in nature I think that the Luis Suarez "Bite" at the world cup is a perfect demonstration of the way that preconception and emotion can effect what we "see" or admit to seeing.
I will try and summerise the incident for those who are unfamiliar with it:
During a match between Uruguay and Italy (which was broadcast globally and had hundreds of journalists, cameramen and photographers recording proceedings) A Uruguayan player "Luis Suarez" appeared to bite an opposing player "Giorgio Chiellini" and the incident was caught on film, not to mention that tooth marks were visible on Chiellini's skin.
In "real" time it is hard to tell exactly what happened, but in slow motion
I can clearly see that Suarez bit him. And given that he has done the same thing on at least two other occasions I have no doubt that he did, however the Uruguayan players and media have rallied together and claim that Suarez did nothing wrong and that it is part of an "English" and European conspiracy or smear campaign against Suarez and Uruguay because Uruguay beat England in the previous match and Suarez scored the winning goal. Their (Uruguay's football team and media) motivations are pretty obvious to me: in that if Suarez is found guilty of misconduct their best player will play no further part in the tournament meaning they have a diminished chance of progression in the competition.
I find it astonishing that given that there is both visual and physical evidence and that Suarez has previous convictions for biting they can attempt to deny any wrong doing.
Lets be clear I am only too well aware of the dirty tricks employed by the British media e.g Phone hacking, and also the bias, prejudice and short sightedness of some England fans but in this incident I agree with them, which is highly unusual for me, because I have witnessed similar incidents where English players and even managers (coaches) have been caught red handed and the press have behaved in a similar way to how the Uruguayan's are now reacting.
I hope this all makes sense and that you understand why I see parallels between this incident and contradictions in paranormal eye witnesses and their reports, but if not I am very happy to expand or explain any of part of it.
Here are two articles you may find interesting (they include the video evidence and still photographs of the bite marks)
BBC Sport - Luis Suarez 'bite' controversy: Disbelief & denial at World Cup
BBC Sport - Luis Suarez: global scrutiny after Giorgio Chiellini 'bite'