I Came across something called the Bradley effect on the news channel thanks to the world attention on American presidential election.
This is what Wikipedia has to say on Bradley effect
I think it is not only about black candidates. This theory has a wider context which is that in general people prefer to say what is more acceptable and fashionable rather than what they actually feel when it comes to opinion polls.
I have always felt that opinion polls are more a creation of the media to build a hype rather than something useful. I think this theory makes sense and there are enough examples that stand testament to that.
Will the Bradley effect influence the current polls and prove the opinion polls wrong? We will have to wait for a few hours to see ..