Bystander effect

In this week's chapter you read about deindividuation,  authority as an instigator in criminal behavior, and the bystander effect.   The people who are not primary actors in violent crimes, but may instead be part of the onlookers, are often guilt ridden that they did not intervene when they are interviewed after the fact. 

(A) What tactic in this week's chapter can be used to re-direct some outcomes?  There is a specific answer, so don't be afraid to list out the theories and situational factors and then consider how to reapply that theory.