 The strategy can also depend on who the candidates are. If a sitting president is running against an unknown challenger, the advertisers won't even mention the opponent, so as to not increase name recognition with the audience. But with two or more well-known candidates, advertisers choose a different strategy that often highlights the candidates' values and past actions, or lack thereof. Dr. Richard Petty notes that possibly the biggest shift in strategy of the last decade is the rise of negative advertising.