It's basically when one reality collides with another reality and you don't have the ability to say I'll pick reality 'A' instead of reality 'B'. You have to figure out a way to coexist with the current reality and it usually produces some kind of dysfunction.
Cognitive dissidence is what happens to children when they're molested by a parent where their total source of security is also the source that betrays them.
This is also relative to Germany and the peoples response to Hitler.
Another example for United States citizens, where some people who were saying they had to vote for the man with integrity, therefore they had to vote for George W. Bush. Now that it has been made so apparent to all of us that Bush and his administration are a source of betrayal to our Constitution and our true values.
These are just a few examples but it goes way beyond these. It can happen in a million different ways.