Read the passage.
The Great Debate
On September 26, 1960, seventy-four million viewers tuned in to watch a historic duel: the first televised presidential debate. The candidates were a young, relatively unknown Massachusetts senator named John F. Kennedy and the more experienced incumbent vice president, Richard M. Nixon. Although historians note that the candidates were equally skilled speakers, the differences in their televised performances were considerable. Viewers thought that Nixon, who had recently been hospitalized for an injury, appeared sallow and sweaty; by contrast, Kennedy looked handsome and relaxed. As Kennedy spoke, he fixed his gaze on the camera to address at-home viewers. On the other hand, Nixon directed his responses to reporters off camera, which made him seem cold and distant to television viewers. The differences in their appearances had a dramatic effect. Some people even recall that when they listened to the debate on the radio, they thought that Nixon had won, whereas when they saw clips on TV, they thought Kennedy was the better debater.
What is the main, or central, idea of the passage?