Not exactly, Cognitive dissonance is where you have cognitions (thoughts/ideas) that run contrary to each other, which triggers to anxiety. The theory is that people will try to eliminate the anxiety by altering their cognitions to remove the dissonance. (oh and this is normal behavior)
http://en.wikipedia.org/wiki/Cognitive_dissonance
What I think you are thinking of is confirmation bias (also considered normal)
http://en.wikipedia.org/wiki/Confirmation_bias
And another thing that is probably going on is cognitive bias
http://en.wikipedia.org/wiki/Cognitive_bias
Now stuff like denial and distortion are more in the area of mental illness
http://en.wikipedia.org/wiki/Ego_defense
But mostly I would chalk the results up to good ol' ignorance and apathy. Being informed and staying informed takes effort and action, and many people are just too lazy to bother, so they rely on the popular media (a junk source of information) to feed them their opinions and thoughts.