While political history is definitely one of my hobbies, psychology is my profession, and examining why people do the things they do has long interested me.

Each election year, we hear a constant stream of "I'm so sick of the negative ads this year..." from our friends and family. It seems that everyone hates them, so why do the candidates continue to use the strategy?

The simple answer: They work.

In fact, they work so well that they have been employed since the earliest days of the Republic.

Early Negative Advertising

Dirty politics is in our blood. From Thomas Jefferson calling John Adams a hermaphrodite and a warmonger to Andrew Jackson being accused of cannibalism, this has been the primary strategy in elections.

Candidates called each other drunks, sexual deviants, atheists, or cowards, regardless of the truth behind the statements.

Libel and slander laws were not nearly as strong during the 18th and 19th centuries as they are today, which led to almost anything being printed in the newspapers that would increase publication.

But not all campaigns have been nasty and it's important to note what happens during a clean campaign.

1944: A Clean Campaign

Probably one of America's cleanest campaigns in the 20th century was the 1944 re-election of Franklin Roosevelt to his fourth term in office.

FDR had almost insurmountable popularity -- the economy was up, the war was going well; it was going to take something incredible for him to lose the election.

His Republican opponent, Thomas Dewey, a fellow New Yorker, ran one of the most honorable campaigns against Roosevelt. He purposefully avoided attacking the president's failing health, which was probably the one issue that might have rung true with the voters.

While a huge concern today, presidential health was a non-issue until after FDR. George Washington was probably the sickliest of all of our presidents and it was almost never commented about in the newspapers -- though he really didn't face very much real competition. Taft got plenty of publicity about his weight; yet it was his politics that ultimately derailed him. It was FDR's death in office that sparked America's obsession with presidential health.

Even the press bent over backwards to be respectful of Roosevelt's confinement to a wheelchair, with only three known photographs of Roosevelt sitting in a wheelchair known to exist.

By 1944, Roosevelt's health was seriously on the decline. A lifetime chainsmoker, almost all of his health problems (other than the polio) could be attributed to smoking. Yet, his personal physician declared his patient "perfectly OK."

There is some speculation that Roosevelt used his power over the Office of Censorship to keep his health out of the papers, but Dewey didn't even address these issues much on the campaign trail. Others contend that Dewey didn't want to give the Nazi propaganda machine any further ammunition, but this seems unlikely considering what the Nazis were already calling Roosevelt and Churchill (which was basically the invalid and the drunk).

Dewey took the high road and finished in second place. And that is the unfortunate reality -- that the nice guy finishes last.

Research on Negative Campaigning

There's quite a bit of scholarly literature on the subject of negative campaigning, a good portion devoted to trying to figure out why it works.

Some of it is through voter frustration. Negative campaigning tends to decrease voter turnout; especially, when it reaches a level of constant bombardment. It's not uncommon at this point to hear stories of 22 or more political ads during a single 30-minute television show, but what effect does this really have?

Indiana University researchers found three unique points.

First, they found that all political advertisements are unpleasant events to our minds, as measured by changes in the EMG activity. Negative advertisements had more severe indications of unpleasantness, but even the most positive advertisement stimulated the brain and muscles in negative ways.

Second, negative advertisements are remembered much clearer by viewers, including candidates' name and the particulars of the negative ad.

Third -- and probably most important from a psychological perspective -- is that measuring the "startle response" indicates that our fight or flight response is triggered by negative advertisements; we are repulsed, both mentally and physically, from the images.

This last point at least partially explains why negative advertising affects voter turnout. Viewers are repulsed by everything connected to the advertisement: the candidate, the opponent, and the political process.

Historical research has consistently indicated that lower voter turnout favors Republican candidates. This axiom has long been based on the philosophy that Republicans had more dedicated voters, yet trailed in overall numbers.

In January 2014, Gallup projected that Republicans made up 25 percent of voters, while Democrats made up 31 percent, and independents made up 42 percent.

The Center for Responsive Politics estimates that the 2014 election will total almost $4 billion, with over $1 billion from anonymous sources. With all of that money, the question remains: what are they actually buying?

Are they informing voters or are they just trying to turn voters away from the entire process? Whatever the strategy, the Republicans clearly outsmarted and outspent Democrats and independents this past election. It's disheartening to even think that part of their strategy could have been one of trying to make voters too fed up to vote.

In particular for 2016, independent campaigns are going to have to work harder and smarter if they are going to be effective. There is no possible way to battle the money of Super PACs and large-scale donors like Sheldon Adelson or the Koch brothers. Independents need to find ways of getting voters to the polls and keeping them focused and not discouraged from the steady diet of negative political advertising.

The era of the multi-billion dollar elections is here to stay, but hopefully solid messages and common sense can help independent candidates combat the big money and negative advertising of the major parties.