Contrary to the popular perception that McCain has spent more time alleging incriminations, Obama aired more negative advertising last week than did the Arizona Se, revealed a study released yesterday.  

If 56 percent of the ads aired by the McCain camp were negative then 76 percent of those produced by Obama campaign were of similar nature.

Ken Goldstein, who directed the study by the Wisconsin Advertising Project, based at the University of Wisconsin, is of opinion that the pattern was a U-turn from earlier months, in which McCain's advertising was more negative than Obama's.  

"It suggests that the Sarah Palin pick and the newfound aggressiveness by McCain got into Obama's head a little bit," Goldstein said. "He was under great pressure to show some spine, be aggressive, fire back."

The study reveals that the campaigns spent $15 million in the battle of ads last week.

Obama spent more on ads in Florida, $1.3 million, but that was nearly in line with McCain's $1 million. The maximum that McCain spent was in traditionally Democratic Pennsylvania, $1.6 million to Obama's $948.000.