The story everyone knows about the first Kennedy-Nixon debate on 26 September 1960 goes like this: those who watched it on television thought Kennedy won, those who heard it on the radio thought Nixon won, and modern politics began.
The story is better than the evidence. It rests largely on a single Sindlinger survey with a small radio subsample, methodological problems, and no random assignment — radio listeners in 1960 were disproportionately rural and southern, which is to say disproportionately Democratic in some respects and demographically distinct in ways that could easily produce the result on their own. Historians of the period have been picking at it for decades.
The circumstances of the debate, though, are not in dispute. Nixon had injured his knee, been hospitalized for two weeks with an infection, and lost around twenty pounds; his shirt collar was visibly loose. He refused professional makeup and was given a drugstore product called Lazy Shave over a heavy beard. The studio was hot, and he sweated through it. He had campaigned all day. Kennedy had rested, was tanned, wore a dark suit that separated cleanly from the light background, and had been briefed on how to sit and where to look. When Kennedy spoke, the cameras cut to Nixon, who was visibly reacting.
So the folk claim was plausible and the evidence for it was bad. James Druckman resolved this in 2003 by doing what nobody had done in 1960: running the experiment.
He randomly assigned participants to watch the debate on video or to listen to the audio only, using the original recordings, with subjects who had no memory of the event. Televised viewers evaluated Kennedy more favorably than audio listeners did, and — the more interesting finding — they weighted image and personality more heavily relative to issue positions when forming their overall judgments.
The mechanism is channel-dependent priming. A visual presentation makes appearance-based inferences accessible, and appearance drives trait attributions: competence, vigor, health, trustworthiness. Work by Alexander Todorov and colleagues has since shown that judgments of competence from a face after a tenth of a second exposure predict real election outcomes at rates well above chance. The eye supplies a verdict before the argument has been heard, and the argument is then evaluated by someone who already has one.
Which is why so much of political production is now about the picture rather than the sentence. Lighting, camera height, background, the color of the tie against the backdrop, the reaction shot, the split screen, the walk to the podium, the choice of whether opponents stand or sit. None of these are about what is being claimed.
The countermeasure available to an individual is unusually simple and almost nobody uses it: read the transcript, or listen without watching. Druckman's experimental design is also a defensive protocol. When you strip the visual channel, what remains is the argument, and the difference between your two judgments is the size of the effect the staging had on you.
See Defense: judging arguments without the picture