Hmm. Interesting research paper called to my attention recently:
Recent studies of campaign advertising typically assess the response of voters to advertisements only from the last few weeks before the voter is interviewed. In so doing, they implicitly assume that the effects of advertisements decay over time. This paper attempts an explicit estimate of the rate of this decay for the Annenberg survey of voters in the 2000 election. Our results indicate that decay is fairly rapid. Even when the persuasive effect of ads on candidate preference is large, 50 to 75 percent of the effect dissipates within the first week and almost all is gone by the end of the second week. Along with other recent evidence, this tentative finding undermines the view that American voters are persuaded by information that accumulates during long campaigns and suggests instead the importance of tactical maneuvers by candidates to dominate the airwaves at the very end of campaigns.
Almost every ad from before mid-October is forgotten?
Sounds like an argument for keeping your powder dry, and helps explain why Team Obama thought the half-hour program was worth it.
Which also makes it interesting that McCain has been closing the gap in the number of ads. Obama still has a considerable advantage, but commercial breaks are no longer all-Obama, all the time…