University of Missouri communication professor Bill Benoit –an expert on campaigns, ads and debates — has offered up an analysis of last Friday’s first presidential debate, compared to its predecessors.

The upshot: Not much has changed.

His content analysis of the exchanges and comments of Republican John McCain and Democrat Barack Obama:

“Most of the statements in this debate were positive (53 percent), followed by attacks (39 percent) and defenses (9 percent).”

Benoit compared previous debates, in 1960 and 1976-2004, and found them “similar in tone: 57 percent positive statements, 35 percent attacks and 9 percent defenses (refutations of attacks).

“The first debate of 2008 was a bit more negative than past elections’ debates, but not vastly more negative,” his analysis said.

“It might seem as if these debates are more negative than this because the news highlights attacks,” Benoit said. “Reporters quote or paraphrase attacks significantly more than the candidates use them in debates.”

“Benoit said that although there is no true incumbent in this race, McCain is a representative of the incumbent party – and Obama worked hard to link McCain with President Bush. Only Obama mentioned the president by name (10 times), and four times Obama directly linked the two.

“Analysis of the first debate shows their comments were distributed as if McCain was the incumbent and Obama the challenger: McCain had more positive statements and fewer attacks than Obama, which is true of incumbent candidates in the past. Given the fact that President Bush has low levels of popularity, it is not surprising that Obama would work to link McCain and Bush.

“According to Benoit’s analysis, one unusual feature of the debate was that McCain was the target of more attacks (Obama attacked in 42 percent of his debate statements while McCain attacked 34 percent of the time) but Obama used defenses more frequently (Obama 12 percent, McCain 5 percent).

“Usually, the candidate who is attacked the most defends the most.”

Benoit observed that “some have suggested that one factor contributing to (Democrat) Michael Dukakis’ loss in 1988 was that he defended too little and too late. On the other hand, Bill Clinton’s 1992 campaign was known for its quick responses to attacks.

“The two candidates discussed policy more than character, 73 percent to 27 percent, in this initial debate,” Benoit said. “This emphasis is almost exactly in line with past presidential debates, 75 percent policy, 25 percent character.”

Regarding Thursday’s vice presidential debate, Benoit noted that the “first vice president debate occurred in 1976. No debate between the vice president candidates was held in 1980; in that year only one presidential debate featured the Democratic and Republican candidates (Carter and Reagan) and it was held only eight days before the election. In 1984 the vice presidential debates resumed and have been held in every campaign since.”

“Content analysis shows that vice president debates are somewhat like presidential debates: vice president debates have more attacks (40 percent to 34 percent) and fewer defenses (2 percent to 8 percent), but the level of positive statements is virtually the same (vice president debates 57 percent, president debates 58 percent).”

“…Both kinds of debates stress policy (vice presidential 69 percent, president 75 percent) over character (vice president 31 percent, president 25 percent). It is not surprising that the running mates talk a bit more about the candidates of the presidential candidates, but again there is not a huge difference.”

We’ll see how Thursday’s face off between Republican Sarah Palin and Democrat Joe Biden fits in.