“My opponent is a liar. And, he can’t be trusted.”

Did you ever wonder why there are so many political attack ads? Of course, politicians have the obvious desire to tear down the opposition in the hopes of building up their own position.

But there is another dynamic at work: candidates and campaigns are seeking to exploit the lesser-known psychological advantage that opposing the other candidate has over supporting one’s own.

On candidates and issues alike, people can think of themselves as a supporter or as an opposer. If we assume the current front-runners become the presidential nominees, this is the difference between “I support Hillary Clinton” and “I oppose Donald Trump.” Both positions would likely result in the same voting intentions, but one is more likely to inspire action, such as participating in a demonstration, contributing funds or actually casting a ballot.

Our research into the question of how voters think of themselves has discovered that opposition inspires more confidence in one’s position than support. Confidence helps to turn judgments into actions. This helps explain why political attack ads are a crucial tool in politicians’ arsenals – and why voters are bombarded by negative messages on the way to the voting booths.

Perspective leads to confidence, and then to action

It is not that opposers are different kinds of people (negative Nellies or pessimists) than supporters (Pollyannas or optimists). Nor is it that opposers necessarily have different reasons behind their views than supporters. For example, those who oppose discrimination may not have had more personal experience with the issue than those who support equality, nor are they necessarily more emotional about the issue. Yet, being anti-discrimination is more confidence-inducing than being pro-equality.

Our research shows that if a person merely changes her view of her position, from saying she supports something to saying she is against its opposite, her likelihood of behavior changes. The perspective shift increases the confidence she has in her position. Our research also shows that people are more likely to act on their attitudes when they are held with confidence. For example, if two people like a new car to the same extent, the person who is more sure of that feeling is more likely to buy the car.

As a test of this hypothesis in the context of a real election, we conducted a study during gubernatorial campaigns in two East Coast states. In preelection surveys, a representative sample of potential voters was randomly asked about support or opposition to either the Republican or the Democratic candidate.

Typically, when Democratic voters were asked about the Democratic candidate, they would reply that they “supported” him, but if they were asked about the Republican candidate, they would reply that they “opposed” him. The inverse situation was typical for Republican voters.

Our survey questions were designed to get voters to momentarily think about their position as either supporting their preferred candidate or opposing the disfavored candidate. This simple framing did not affect how much people liked their preferred candidate. But, it did influence how confident they were in that view and their intended behaviors. Voters who focused on how much they opposed the other candidate were generally more confident in their preference than voters who were asked about how much they supported their candidate.

Even more importantly, thinking about their opposition to the other candidate made voters report being more likely to engage in favorable behaviors toward their own candidate such as volunteering for him, advocating to others and going out to vote for him. That is, when we got voters to focus on the candidate they opposed, the voters appeared to have deeper conviction and reported a greater willingness to be politically active.

Our finding that being an opposer is more powerful than being a supporter fits with other psychological research showing that negative traits and information are typically weighed more heavily in judgments than positive traits and with the prospect theory notion that losses loom larger than gains.

Anger is stronger than fear

But what if you are competing in a primary rather than a general election? In that scenario, it’s often more difficult to get voters of your party to actively oppose other candidates from the same party, though as this election cycle shows, it can happen! Is there a way to enhance the confidence voters have in your candidacy?

Our research indicates that the reasons people support you can influence their confidence and tendencies to act on your behalf. For example, if people support you because they are angry at the establishment, or government, or immigrants, this anger can fuel them to feel confident about supporting you.

Although both anger and fear can influence what particular positions people take on issues, anger is a confident action-oriented emotion, whereas fear is more passive and doubt-oriented. Voters who support a candidate because they are angry at something are more likely to be confident and take action than voters who are frightened.

According to one recent poll, six in 10 Nevada caucus-goers this year described themselves as angry. Voter anger may be one reason why turnout in many of the primaries so far has set records.

In sum, our recent research has demonstrated that knowing how much voters like particular candidates, though important, is not the whole story. It also matters how confident people are in their preferences, because confidence is what turns attitudes into action. Knowing whether candidate preferences are driven by support or opposition, and by anger or fear, can help more accurately determine who is likely to donate money, show up for caucuses and ultimately vote for the chosen candidate.