"An individual's reactions to those elements are often happening at the subconscious level," he says, "hard-wired by our biological and genetic predispositions and evolutionary predispositions."

In the 21st century, with so many means of communication available, optics are stressed more than ever.

Some are old: Yard signs are still effective because they appeal to community, says Panagopolous. Some are new: Internet ads and social media can identify voter tendencies through search algorithms. Some combine today and yesterday, such as flyers that can be precisely targeted through direct mail.

Do they really change minds? Experts still argue the question.

"I'm not quite convinced the American people are troubled by a politician not wearing a flag lapel pin," says Robert Eisinger, a political scientist and dean at the Savannah College of Art and Design (SCAD). "Consultants and advisers believe it's important, but I'm more skeptical."

On the other hand, you never know what makes a difference: He refers to one study that indicated a split-second look at two candidates' faces was enough for observers to discern the winner.

"We're still trying to figure out why," Eisinger says. "The political psychologists are exploring what is it about image that appears to matter?"

The faces of America

Politicians don't necessarily care about the "why." They just know optics work.

To that end, campaigns spend a lot of time showing the many faces of America. Thanks to modern media, the campaigning works on local, regional and national levels.

Matt Mackowiak, a Republican consultant and former advance man for the 2004 Bush-Cheney campaign, saw that firsthand. By the time the campaign came to town, Mackowiak and his colleagues had already worked with local leaders to underline the campaign's point (rounding up doctors for a speech on health care, for example), had people vetted so that they didn't step on the message -- and made sure to showcase a demographic smorgasbord. The appearances would inevitably make the national news; some of them would be re-purposed for TV commercials.

"Generally having a backdrop of other people provides a depth and a color to an event that makes it look more alive," he says.

There are drawbacks. At a live event there's a risk of showing drowsy faces or a fatigued candidate. That means there's little time for nuance, says Middle Tennessee State political science professor Kent Syler.

"As issues have become more complicated, attention spans of voters are shorter because there is so much information out there," says Syler, a former campaign manager and congressional chief of staff. "It has made symbolism and appearance even more important. Voters will fall back on whether or not they feel good about the person."

Campaigns weren't always so detailed -- and they didn't need to be. In the 19th century, politics was entertainment, notes Brian Balogh, a historian at the University of Virginia. It was a big deal when a presidential campaign came to town -- a day full of speeches and picnics and rallies around bonfires. The candidate himself need not attend; in fact, until about 1896, anybody who wanted to see them in person generally had to travel to the candidate's home. (Campaigns obliged by offering railroad specials for supporters.) The traveling rallies were full of surrogates.

Moreover, elections weren't all about the presidency, he adds. "They were much more about mobilizing the troops" for the many other slots on the ticket.

The rise of new technologies changed all that. Warren G. Harding benefited from movie newsreels, appearing with the stars of the day while giving speeches from his Ohio house. Franklin D. Roosevelt was a shrewd user of radio.

But television had the biggest impact.

TV emphasized the visual. TV rewarded cool. TV brought local scenes into living rooms all over the country, making the optics even more important.

Candidates adapted quickly. Dwight Eisenhower hired the pioneering adman Rosser Reeves for his 1952 campaign. John F. Kennedy wrote an article about the future of politics on TV for TV Guide magazine in 1959. The next year, when he ran for president, Kennedy's commercials stressed his youth and vigor, and his debate performance against a pallid Richard Nixon impressed viewers.

"This is a guy - and his campaign - who (was) aware of how television is shaping how people are processing politics," SCAD's Eisinger says.

Ronald Reagan took stage management to new levels when he was president. The former actor was well aware of the value of good lighting, colorful vistas and carefully controlled presentation, and for his 1984 campaign, his team -- including aide Michael Deaver -- pulled out all the stops.

"Mike was a master of choreography of events," says Harvard professor and CNN contributor David Gergen, who served in Reagan's first term. It was Deaver who was responsible for backlighting the Oval Office for Reagan's prime-time presidential addresses, Deaver who made sure the president was photographed from high angles so his neck wattles didn't show. Reagan, still the oldest man to have held the office, was also presented with a youthful vigor. He even re-created a Harry Truman-style whistle-stop tour, waving regally in front of thousands who gathered to watch his train go through -- scenes that made it into an advertisement.

Eight years later, Bill Clinton took the concept of surrounding himself with an audience of average Americans - rather than the backdrop of a formal dais -- and made it central to his campaign, says Darrell West, a political scientist based at the Brookings Institution. It's now de rigueur for presidential candidates.

"When the television cameras were reporting what he said, it would be against a backdrop of a multicultural audience," he says. "A lot of candidates (now) like to have the audience seated behind them, because it conveys leadership and having followers at the same time."