Emotional manipulation is the exploitation of someone's deep longings or fleeting attitudes, for one's own benefit. It is usually associated with propaganda or advertising campaigns. Emotional manipulation to persuade people to believe an assertion on something other than that assertion's merits constitutes the logical fallacy of appeal to emotion.
For instance, to sell cars or tools to a man, advertisers typically show an attractive woman in the same picture as the product.
Rather famously, Barack Obama sold "hope" in his 2008 Presidential campaign.