The following comes from freeminds:
http://www.freeminds.org/psych/openmind.htm
It is rare to find a Witness who has not seen or heard information exposing the dishonesty of the Watchtower. Why, then, do they not see a problem? Evidently, something else has prevented them from objectively analyzing factual information. Their minds are trained to stop short of doubting the organization - a wall has been erected which says, in effect, "This far you may go, and no further."
What kind of powerful motivation prevents the Witness from entering the "dangerous" waters of critical investigation? The motivation is fear; the underlying problem is misplaced securities. The Christian concept of trusting a supernatural God is replaced with a more visible and concrete symbol, namely, the organization; God's organization. The Witness learns that serving the organization is the same as serving God. The organization is the mother, God is the father, and the Witness is to obey his "parents." Since the Witness cannot see nor experience real interaction with God, his only tie with God is through the visible organization. It is, in effect, "God" to him (though he would not admit to or recognize it).
Convincing the Witness that the organization is deceptive is like trying to convince a 5-year-old child who loves his parents that his father is in jail for armed robbery - he simply doesn't believe his father is dishonest. In fact, he can't tolerate the thought, since he has placed all of his security and trust in his father and mother. The truth is too fearful and devastating to consider. Therefore, to protect his source of security, he rejects the factual information as being a lie.
The same is true of the Witness. He knows that if the organization is not really directed by God, he has no other tangible security to go to. He says, "Where else can I go?" So he remains within the system as years go by, continuing to ignore the barrage of factual information undermining the entire Watchtower structure. The more and more he ignores the facts, the more narrow-minded and adamant he becomes that he will never change, and he is more convinced than ever that he has the truth. He digs himself into a trench, erecting all sorts of mental barricades against his real enemy, which is doubt. While this seems incredible to the person trying to reach the Witness with the facts, it is just a simple protective mechanism, keeping the Witness from the trauma of losing his sense of security. In order to rationalize away the false prophecies and inconsistencies of the organization, the Witness must, in effect, deceive himself into thinking there is really no discrepancy in the organization. 1
While Christians have their security in a spiritual relationship with the person of Christ, Witnesses are taught to put faith in an organization. If they have faith in the organization, they have faith in God. The two are inseparable; so much so, that to lose faith in the organization means a corresponding loss of faith in God. This is precisely why the Witness must protect himself through the process of self-deception. He cannot bear the pain of losing his faith.
(the arcticle continues)