“Informal social control is exercised by a society without explicitly stating these rules and is expressed through custom, norms, and mores using informal sanctions such as criticism, disapproval, guilt and shaming. This implied social control usually has more control over individual minds because they become ingrained in their personality.”

http://www.wordiq.com/definition/Social_control

I think this is more appropriate than “bystander effect” - similar principle but not as full on. Look into it and tell me what you think…

S