Republican presidential candidate Donald Trump released an attack ad in early March that called then-candidate Marco Rubio a “corrupt, all-talk, no-action politician.” Political attack advertisements like Trump’s become more prevalent as the election season progresses.

Research conducted by researchers at Ohio State revealed that attack ads are effective.

The research showed that being against a candidate will make voters more confident and action-oriented than being in favor of their candidate. If voters consider themselves as opposers rather than supporters, they are more likely to vote in general, donate money or show up at a campaign rally.

Social psychologists have known for some time that people tend to give negative traits of a person more weight, said Richard Petty, a professor of psychology who co-authored the study. Petty’s research helped examine negativity and how it relates to confidence.

When something good is going to happen, people often sit back and wait for it to happen, Petty said. So Petty and his co-workers hypothesized that negativity can be associated with confidence and tried to prove it in the political domain.

Confidence is what turns people’s thoughts into judgments and turns their judgments into actions, Petty said. Moreover, negativity is related more to action than positivity.

“If I tell you that something bad is going to happen, you will become anxious,” Petty said. “What should I do? What is it going to be? You will try to go to an action orientation because you need to stop that bad thing from happening.”

Researchers called people and randomly asked what they think of Trump or Hillary Clinton. People were given the opportunity to state their stances as they support one candidate or oppose the other candidate. Normally, Democratic voters would answer that they support Clinton or they oppose Trump, Petty said.

“When we asked them the question of whom they supported or opposed, we didn’t change whom they supported or opposed,” Petty said. “We also didn’t change how much they supported or opposed a candidate.”

But when researchers later asked people whether they planned to vote or donate money to their favored candidate, those who said they opposed a candidate were more likely to say they would vote or donate money to another candidate’s campaign, Petty said.

“The action of trying to vote came from feeling more confident,” Petty said. “The opposition mindset makes people more confident so that they turn their attitudes into the desire to do something.”

Therefore, negativity is often used as a strategy to convince people of their opinions, said Andy Luttrell, Petty’s student and a sixth-year doctorate student in social psychology.

“Say some people are Bernie Sanders supporters, instead of talking about how great Sanders is, it might be a better strategy to get other people to think of how much they dislike the other candidates,” Luttrell said. “Because ironically, it would make them feel more sure that Sanders is the right candidate for them.”

As negative advertising becomes more prevalent in the election campaign, Petty said he thought that perhaps all the voters could become equally negative and the overall effect might not be especially impactful.

Generally, with traits, people expect everyone to be positive, so when people expect positivity, they weight negativity more because it is more rare, Petty said.

Petty added that when people expect every political advertisement to be negative, positive advertisements carry more weight with media consumers.

“What’s unknown is whether people will have the motivation to go out and do something about it because it’s still something good,” Petty said. “When things are good, we feel like we should just let good things happen and don’t have much motivation to make them happen. But liking is the first step. Maybe liking combing with negativity toward other candidates might help.”