Have you ever wondered why Jehovah's Witnesses can't get baptized by their Bible Study conductor in their private pool? Or why they don't get baptized at their local Kingdom Halls? Why do they "make a public declaration" before thousands?
The answer lies, as it does in so many of the Watchtower's practices, in social influence and conformity.
Deutsch and Gerard conducted a study just a few years after Solomon Asch (1955 to be exact) which is known for defining informational social influence and normative social influence, the psychological need to be right and the need to be liked, respectively. What Deutsch and Gerard also found was that public declaration of a decision hardened the subjects commitment to that decision even in the face of evidence that the decision was wrong. There is a powerful psychological drive to remain consistent because consistency is valued socially. We have numerous derogatory terms for those who change their minds: wishy-washy, flip-flopper, airhead, weak-minded, etc. We are also often complimentary of those who remain consistent: level-headed, cool customer, strong-minded, etc.
So people want to remain consistent with their prior decisions and people want to be right and to be well liked.
When they have made a decision publicly, they will thereafter fight tooth and nail to maintain it: ignoring, avoiding, and denouncing contrary evidence (therefore remaining right) and by favoring the continual association with those "witnesses" to that "public declaration" (therefore remaining well liked).
Surely there is no difference in the water in the temporary pool on the floor of the civic center and the water in your bathtub at home (other than a greater amount of chlorine). So why restrict JW baptisms to huge public events? Mind control. It is to create a situation where the person naturally will avoid any subsequent analysis of the previous decision making process, cease in any analysis of alternative possibilities, and persist in association primarily with confederate "yes-men" who will reinforce the decision to dedicate the rest of his life to the cause.
How much of this psychology and research do the men who create such policies really understand? Are they educated and well-read on the subject? Or is it simply an intuitive decision made by an organization with a natural knack for control? I wonder.
Whether intentional or not, the effects are the same. Many of us know from personal experience how incredibly difficult it is to re-open a mind that has been closed by public declaration of our dedication in the form of Jehovah's Witness baptism.