If Vice President Joe Biden channeled his inner pit bull, Rep. Paul Ryan brought his inner puppy to the debate stage, according to facial expression expert Chris Kowal.
"I kind of call it the bulldog vs. the puppy," Kowal told ABC News.
"[Paul Ryan's] looks of surprise and the smile that he has…he comes across as very cute and likable," Kowal said. "When you pair it up with the more aggressive bull dog type of Joe Biden, people are going to become more protective of their candidate as a result."
Kowal, an assistant professor at Purdue University, used computer software to analyze the facial expressions produced by the nearly 400 muscles in the human face during Biden and Ryan's face-off at Centre College in Kentucky Thursday.
The result is a portrait of what the candidates might have really been thinking as they exchanged jabs on the debate stage.
As Biden's big laughter took Twitter by storm, the computer model lit up with readings of frustration and discomfort—the emotions you might experience laughing at a funeral, Kowal said.
"It's not an uncommon reaction when people see something that really makes them uncomfortable, and frustrated… they might laugh at inappropriate moments," Kowal said. "It was that."
"When I watched him laugh, it was a clear sign that he was frustrated," Kowal added.
When Biden rejected Ryan's arguments as "a bunch of stuff" and "malarkey," the emotional ratings went off the charts.
"When he said malarkey—the passion leading up the comment, the passion and the intensity of emotion was really strong," Kowal said. "He was very angry, very disgusted…sad and all of these three emotions were all in the 'high intense' level."
Kowal said that Ryan aimed to evoke emotional responses through anecdotes several times during the debate. But the most poignant came when he relayed the story of a husband and wife who his running mate Mitt Romney helped after they lost their children in a car accident.
Biden, who lost his wife and daughter in a car accident, responded in a wave of emotion, Kowal said.
"That really touched Biden," Kowal said. "There was an extreme intensity of sadness on his face, when he started talking about his family."
Unlike Biden who has participated in several presidential and vice presidential debates, Ryan is a relative newbie to the national debate stage. And it showed, Kowal said.
He focused intensely on delivering prepared answers on foreign policy, but on budget issues, the House Budget Committee chairman was loose and relaxed.
"If you look at where his head was tilting and the intensity that he had, he was definitely making more of an effort to focus his words and get the talking points out when he was talking about foreign affairs," Kowal said. "His responses on the budget, health care and the abortion issue, he was much more comfortable."
"He knows it like the back of his hand," Kowal said.
Both candidates were chock full of emotion—far surpassing running mates President Obama and Romney in their expressiveness.
"Both of them were extremely expressive guys, both of them had a lot of passion and a lot of anger overall," Kowal said.