The following is a guest post by Brian Arbour. Arbour is an associate professor of political science at John Jay College at the City University of New York. He also serves as a member of the Decision Team for Fox News Channel. 

The Sen. Mark Pryor (D-Ark.) campaign shook up their race against US. Rep. Tom Cotton by releasing an ad last week that focused on Pryor’s vote in favor of Obamacare. Commentators from across the political spectrum have examined the Pryor ad for what it says about the shifting and more favorable political situation of Obamacare in 2014.

The embrace of a provision of Obamacare by an embattled Democratic incumbent running in a red state is certainly new and noteworthy. But the rhetorical strategy of the ad is tried and true.

In the ad, Pryor never discusses what he plans to do in the Senate in the next six years. Instead, he focuses exclusively on what he has done in the past. In the ad, Mark and his father David (who served as both governor and senator from Arkansas) discuss Mark’s battle with cancer and his insurance company, and his support for “a law that prevents insurance companies from canceling your policy if you get sick, or deny coverage for preexisting conditions.”

The ad tells us something about Pryor and what he has done, but never tells us about what he is going to do if reelected.

In my book “Candidate-Centered Campaigns: Political Messages, Winning Personalities, and Personal Appeals,”I show that ads like Pryor’s are quite common. I find that 85 percent of candidate-sponsored ads feature what I call candidate-centered appeals — messages that focus on the past actions or experiences of a candidate, rather than his or her policy ideas and plans. Candidate-centered appeals include not just biographical information (like the discussion of Pryor’s cancer diagnosis), but also the past actions of a candidate in the private sector or in public service (like Pryor’s vote in favor of the Affordable Care Act).

Why do political campaigns choose to use candidate-centered appeals so frequently? They do so in an effort to enhance the credibility and likability of their candidate. I interviewed political consultants, and find that consultants, whether they are Democrats and Republicans, and regardless of whether they are locally, state, or nationally based, all believe that voters are highly skeptical of the claims made by politicians. To overcome this skepticism, these consultants want to use stories about their candidates to show voters “who the candidate is.” These stories are designed to demonstrate what the candidate has in common with voters and to provide evidence of a candidate’s political beliefs.

The Pryor ad shows a classic demonstration of this strategy. The Pryors discuss Mark’s cancer diagnosis in an effort to show a little of his humanity and to make him not seem like a typical politician. Then the ad pivots to politics and shows how Mark’s cancer diagnosis is related to his vote for a ban on insurance exclusions for preexisting conditions.

Campaigns use candidate-centered appeals more frequently early. They do this because they need to first establish their candidate’s credibility before they can move on to future-based policy appeals.

What do I mean by early?  One way is early in an advertisement. The chart show the percentage of 1st, 2nd, 3rd, etc. phrases in an ad that feature a candidate-centered appeals (data are from general election campaign sponsored ads from U.S. House and Senate candidates in 2004). The use of candidate-centered appeals rises quickly and is used in a majority of time in the 5th, 6th, 7th, and 8th phrase of an advertisement. The use of candidate-centered appeals drops off gradually across the rest of the phrases.

Campaigns also use candidate-centered appeals earlier in a campaign. This figure shows a seven-day moving average of the percentage of advertisements aired that featured a candidate-centered appeal about the sponsoring candidate in September and October 2004. Campaigns talk about their candidate’s background, biography, and record a great deal early in the fall campaign season; more than 80 percent of advertisements aired in the week after Labor Day use candidate-centered appeals about their own candidate. These appeals taper off across the rest of the campaign as campaigns air more policy-based and negative advertisements. This pattern is evidence of the importance of candidate-centered information in developing a candidate’s credibility and likeability with voters.

Pryor’s ad does break new ground in the politics of Obamacare, and whether other embattled Democrats follow him in making pro-Obamacare appeals is very much in doubt. What is not in doubt is that others will follow Pryor in making appeals that focus on the background, biography, and political record of the candidate. Campaigns have always done this and have always had good reason to do so.