So we're a few hours away from the Vice Presidential debate and most people have probably processed their thoughts about the first Presidential debate, but let me throw in my two cents, particularly to the reaction of commentators. First, there has been historic empirical evidence that viewers' opinions of who "won" a debate are formed by what commentators say. This herd mentality was in effect last week. Watching the response on CNN, the comments immediately after the debate focused on optics, theatrics, and non-substantive issues, and to that extent all the talking heads said Romney won. However, there was no discussion of which issues either candidate had better (or more factual) arguments. But there was widespread agreement that Obama looked sluggish, so this became the conventional wisdom.
Basically everyone agreed that Romney did at least a little better. Now, this has resulted in what I call the "Rotten Tomatoes" Effect. On the movie review aggregation site Rotten Tomatoes, different reviews are categorized as either positive or negative and the movies are ranked on the percentage of positive reviews. The problem with this methodology is that there is no room for gradation of an individual reviewer's opinion. If everyone thought a movie was just a little below average then that movie gets a "zero" rating, even though no individual reviewer thought the movie was of zero quality. (A far better method is used by Metacritic) The same thing has happened with the conventional wisdom of reviews of the first presidential debate. Basically everyone thinks Obama lost, at least by a little bit. Because everyone thinks Obama did at least a little worse than Romney, the aggregation of those opinions has been perceived as Obama being blown out of the water, even if few individuals held that opinion.