For viewers, that's a good thing, Graham added, saying that voters tend to see aggressive debating tactics as bullying.
"For God sakes, don't actually debate. If you actually debate you tend not to do well in the polling the next day," he said. "The public tends to think they were too aggressive and mean and they don't like them."
Even things like height differences alter perception and the types of gestures a candidate should use, Wade said.
"Most of the presidential primary debates were the standard format of the line of humans behind lecterns. It generates some power dynamics in size difference," she added. "We associate height with power. It's a subtle stereotype that goes on."
So someone smaller, like Rep. Michele Bachmann of Minnesota, "had to use larger hand gestures to compensate with size," Wade said.
At 6-foot-1 and 6-foot-2 respectively, Obama and Romney are on an even footing.