The 2012 Republican and Democratic conventions are over… the delegates have packed up and gone home, leaving Tampa and Charlotte to sweep up the confetti. Mitt Romney experienced almost no bounce in the polls after his big show, and it looks like President Obama isn’t likely to see a significant bounce either. Is the traditional post-convention bounce declining, and does it even matter by November?

“A bounce can be very important. There are elections in recent memory, like 1992 for Clinton, where the convention seemed to matter a great deal. Clinton left the convention with a huge bounce, and much of it held through Election Day,” says Christian Grose of the USC Dornsife College, an expert on elections and media.

Grose says that the impact of Obama’s convention speech may be small because the American public already knows him and thus there isn’t a lot to be learned. “Once a president has been in office for four years, three days of a convention will not matter that much in influencing opinion. However, when a candidate is a challenger or there is no incumbent, the conventions can sometimes lead to larger bounces.”

There are other factors that may have dampened chances of a big bounce. “The polls leading into the conventions were exceedingly close, with both candidates tied or within the margin of error, and only about 5 to 10 percent of voters undecided,” Grose points out. “Those who have already decided are unlikely to be persuaded by a convention. Thus any bounce that Romney or Obama could pick up is limited, given the small percentage of undecided voters. If a few undecideds move in the direction of either candidate, that would be considered a good bounce, given how tight this election appears to be.”

The minimal bounce — a trend that may last beyond the 2012 election — also has to do with fundamental changes in what a political convention is, and how the media covers it. Grose says that less attention is given to conventions today than in the past. “Conventions used to matter for choosing the nominee decades ago, and people paid attention. Following rule changes in the 1970s, conventions became less and less important for choosing nominees, and more of a show for the nominated candidates,” he explains. “In the 1980s, 1990s and 2000s, the media covered the conventions. This year, however, the networks have substantially reduced their coverage. Conventions used to be four days long, but the networks intended to only cover three days, and very few hours at that. With the fragmentation of television, so that viewers can choose to watch reality shows instead of conventions, there simply are fewer eyes on the conventions.”

And fewer eyes mean fewer chances to change minds.

More stories about: Barack Obama, Election 2012