"The most effective campaigns are face-to-face, repeated campaigns. Such campaigns generally have a larger average impact on persuasion, knowledge, and behavior than remote campaigns (such as ones conducted through television or the internet). Negative and positive messages appear to be almost equally effective in motivating behavioral change. Negative messaging does seem to be more memorable than other types of messages. However, if negative advertisements are attributed to an individual or organization, they tend to lead to backlash against the sender. Targeting a message to a particular subpopulation greatly increases the success rate of information campaigns, especially if the targeting stresses peer groups or community norms. Additionally, targeting and knowledge of relevant subpopulations can decrease the risk of unintended or counterproductive results. In complex environments where people are bombarded by a wide range of messages, adversarial messaging efforts tend to cancel each other out." (Key findings)