They have been dubbed the “shouting heads”—television pundits who treat political discussion more as blood sport than reasoned argument. But new research suggests the problem is not just the shouting; our annoyance also comes from the apparent size of those heads.

Shouting combined with extreme close-ups tends to make viewers less tolerant of opposing political viewpoints, according to Diana Mutz, a political scientist at the University of Pennsylvania. “It takes people we would dislike regardless, and then it puts them in our faces in a way that truly intensifies our negative sentiments,” she says.

When we see a magnified face on television, we react as if a real person were pushing into our comfort zone. When that face is also shouting political statements we disagree with, our dislike of the person seems to color our perception of his or her political opinions as well, Mutz observes.

Mutz filmed professional actors engaged in a mock political debate from a medium distance and in extreme close-up. She shot polite versions of the debate, as well as versions with interruptions, shouts and name-calling.

Volunteers who saw close-up shots of rude people they disagreed with were more likely to judge the opinions being expressed as illegitimate. They judged the same rudely expressed opinions as being more valid, however, when the talking heads had been filmed at a medium distance.

Mutz sees disagreement as a healthy part of democracy but worries when people feel that the opposition does not have a legitimate point of view. If these people were to see their side lose, she points out, they might begin to question the legitimacy of the government itself.