(CNN) - If you think the current race for the White House seems more negative than the 2008 presidential campaign, a new study indicates you're right.
According to a political advertising analysis by the Wesleyan Media Project, 70% of presidential campaign commercials that have run so far this cycle have been negative. That compares to less than one in ten ads that ran by this time four years ago that criticized an opponent.
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"One reason the campaign has been so negative is the skyrocketing involvement of interest groups, who have increased their activity by 1100 percent over four years ago" said Erika Franklin Fowler, co-director of the Wesleyan Media Project. "But we cannot attribute the negativity solely to outside groups. Even the candidates' own campaigns have taken a dramatic negative turn."
The study indicates that more than half (53%) of the ads put out by the various campaigns from the beginning of last year through April 22 have been negative, compared to just nine percent at this point in the 2008 election cycle. And 86% of the commercials put out by independent groups, such as super PACs, are negative, up from 25% four years ago.
And ads by the independent groups seem to be dominating broadcast and cable television. At this point in the 2008 cycle, more than 96% of all ads in the race for the White House came from the campaigns. This time around, the campaigns account for just 36% of the spots, with the outside groups responsible nearly 60% of the commercials. The remaining four percent of ads were put out by the political parties.
"Such levels of outside group involvement in a presidential primary campaign are unprecedented," said Travis Ridout, co-director of the Wesleyan Media Project. "This is truly historic. To see 60 percent of all ads in the race to-date sponsored by non-candidates is eye-popping."
According to the study, which used data from Kantar Media/Campaign Media Analysis Group, Crossroads GPS is the biggest spending on general election ads, dishing out $12.6 million to run nearly 17,000 spots in 47 television markets. Crossroads GPS, a nonprofit group that backs GOP causes and candidates, along with American Crossroads, its affiliated super PAC, were co-founded by Karl Rove.
As a nonprofit, Crossroads GPS, like many of the other independent groups putting up ads so far this cycle, does not have to disclose its donors.
"The biggest difference between general and primary election ads so far is that the majority of general election airings and spending has come from groups that do not need to disclose their donors," said Michael M. Franz, co-director of the Wesleyan Media Project. "That's a lot of money and airtime backed by undisclosed sources."
And timing appears to also be a contributing factor in the rise in negative ads.
"At this point in 2008, the Democratic primary was still on going. Whereas in April 2004, you had a president on soft political ground whose road to re-election involved utterly disqualifying his then-known challenger. The same holds for 2012, which explains the negative ads from the Obama camp. Only now, you also have a well-resourced cadre of super PACs and outside groups who are determined to blunt those attacks by launching their own," said CMAG Vice President Elizabeth Wilner.
Another highlight from the study: The Republican candidates relied heavily on the super PACs that supported them to run ads in their behalf during the campaign for the GOP nomination. According to the data, a majority of the ads in support of Jon Huntsman, Newt Gingrich, Rick Santorum and Mitt Romney came from the super PACs backing those candidates. Ron Paul was the least reliant on super PAC ads.