A quartet of political scientists–Amber Boydstun, Rebecca Glazier, Timothy Jurka, and Matthew Pietryka–is spearheading an effort with ReactLabs to measure college students’ responses to the political debates in real time. During the October 3rd debate, for instance, they had 3,767 college students from 120 colleges and universities in 45 states provide at least one reaction via their cell phones. (By the way, for any instructors who want to get their students involved, there is still time–see here.)
Unsurprisingly for a college student sample that was 56% Democratic and 27% Republican, the students were much more likely to register agreement with President Obama than they were to disagree with him, as the figure just below shows. There is essentially no moment in the debate when President Obama’s comments elicited more disagreement than agreement. Students were most positive on his comments about eliminating corporate tax breaks, and most negative when he said he had “kept that promise” to fight for the middle class.
For Governor Romney, agreement to a given comment only slightly outstripped disagreement, a pattern that held throughout the debate. Students agreed with the Governor when he talked about energy independence and foreign trade as sources of economic growth, while they disagreed most strongly with his energy positions on coal and Canadian oil. 
Strikingly, despite the fact that Democrats outnumber Republicans in the sample by more than 2 to 1, Governor Romney was judged the winner of the debate overall by 52% of respondents, as opposed to 48% for President Obama. The reactions came in quickly after the debate ended, limiting (although not eliminating) the effects of post-debate analyses. It seems that a good share of college students are assessing the debate winner based on reactions to the candidates’ performances as a whole, rather reporting a weighted average of their agreement and disagreement. Policy agreement is not a prerequisite for victory in a debate, at least for this sample.
[h/t to Amber Boydstun for the figures]