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."

Running the 'demographics race'

Targeting cultural groups isn't a new development, of course -- those 19th-century candidates played to the ethnic clubhouses of their era. But in the TV age, demographic imagery is often used to emphasize a party's positive outreach and make the candidate look good. Eisenhower's ads included one that featured an African-American, unusual for the 1950s. One Kennedy commercial featured Harry Belafonte, known for his civil rights work; Jackie Kennedy even did an ad in Spanish.

Reagan probably did the most thorough job with his 1984 "Morning in America" commercial, which was as representative as a war movie platoon -- and just as cornily effective. "It's morning again, in America," a grandfatherly voice announced, followed by gauzy, heartwarming scenes of American life: urban and rural, station wagons and picket fences, old folks and newlyweds, children of various ethnicities, capped off by a flag-raising. Almost 30 years later, the images remain as optimistically "American" as sipping lemonade on a porch swing.

Reagan's commercial was a deliberate throwback that reflected the campaign's message of a reborn America after years of splintering. (Clinton's 1996 campaign, which promised to "build a bridge to the 21st century," turned on the same optimism.) But in today's roiled country, the 2012 candidates have to tread more gently on the demographics, say observers.

To San Francisco State's Smith, Obama's campaign seems "concerned that not too many African-Americans appear when he gives speeches," in an effort to highlight the Democratic Party's diversity among other ethnic groups. Romney's campaign, on the other hand, "has the same problem that Republican nominees have had since Nixon," Smith says. "The Republican Party is largely white, but it knows the norms in this country really don't accept that. So they have to go out of their way to appear egalitarian racially and ethnically."

It doesn't take a political scientist to observe that the GOP is trying to come to grips with a demographics gap. During the Republican convention, the party made sure to highlight a diverse group of speakers, including the Hispanic Sen. Marco Rubio of Florida, Indian-American Gov. Nikki Haley of South Carolina and Utah congressional candidate Mia Love, who is black, Mormon and of Haitian heritage. But the rank-and-file, which was also greatly on display, remains largely white: According to a 2011 Gallup survey, party identifiers are "significantly more likely than the overall population to be non-Hispanic whites."

As Sen. Lindsey Graham (R-South Carolina) put it during the convention, "The demographics race we're losing badly. We're not generating enough angry white guys to stay in business for the long term."

Wedges and subtexts

Indeed, optics can just as easily be used as a wedge.

A 1972 Nixon ad, for example, showed a hard-hatted construction worker eating lunch while a narrator described a bill from his Democratic challenger, Sen. George McGovern, that would expand welfare. The subtext was hard to miss: blue-collar workers versus those mooching minorities.

Sixteen years later, George H.W. Bush visited a New Jersey flag factory and turned patriotism into a campaign issue after noting his opponent, Massachusetts Gov. Michael Dukakis, had vetoed a Pledge of Allegiance requirement.

Presidential campaigns generally avoid making an overt issue of race, but as The Root observes, that's not always the case down-ballot.

North Carolina Sen. Jesse Helms made a brutal ad against his competitor, African-American mayor Harvey Gantt, showing a white man crumpling a rejection letter while a narrator intoned about "racial quotas." More recently, an ad by Louisiana Sen. David Vitter said opponent Charlie Melancon was practically "putting out a welcome sign for illegal aliens." Both senators won their races.

But presidential contests haven't gone unscathed. Most infamously there was the Willie Horton ad, used by Bush's 1988 campaign against Dukakis as a way of characterizing him as soft on crime. The ad told the story of Horton, an African-American inmate who had kidnapped and brutalized a couple while out on a weekend pass. The bearded Horton was every white suburbanite's nightmare of the angry black man.

This year there are any number of wedge issues - including Medicare, immigration and welfare - and the demographic battlegrounds are equally numerous.

Meanwhile, optical precision keeps getting sharper.

For example, both parties have generally treated Hispanic voters as a monolithic entity, says Jill Hanauer, president of the left-leaning consultant Project New America. However, her firm's research indicates that adding specific cultural symbols to appeal to slivers of the Hispanic audience can make the message more effective.

"Authenticity is important and it's meaningful," she says. "In the old days, both parties would do a bilingual piece of mail and maybe do one late-in-the-campaign radio spot in Spanish and call it a day. Campaigns now do deep research to understand who their target audiences are among Hispanics, what their audiences care about, and communicate appropriately."

'It's a television show'

All this focus on looking good on TV gets back to a primary criticism of optics: that they are all about style over substance. It's not a new jibe.

In his 1969 book, "The Selling of the President 1968," Joe McGinniss had fly-on-the-wall access for Nixon's victorious run. Nixon had learned his lesson from 1960: in '68, he put together a team of advisers to mold his television image, including "Laugh-In" head writer Paul Keyes, former CBS executive Frank Shakespeare, ad man Harry Treleaven and a producer named Roger Ailes, who had been working for former big-band singer Mike Douglas' daytime talk-variety show. (Ailes is now head of Fox News.) Together, Nixon's team played to the candidate's strengths and minimized his weaknesses ("Avoid closeups," wrote Treleaven in one memo).

Today, the book's details may seem old hat -- but still make for revealing reading.

For example, during the campaign, the advisers filled a panel of questioners with a then-contemporary version of diversity: one African-American ("Two would be offensive to whites," McGinniss wrote. "Two would be trying too hard"), a Jewish attorney, the president of a Polish-Hungarian group, a suburban housewife, a businessman and a representative of the white lower-middle class. The audience, recruited by the party for the hourlong advertisement, was similarly balanced. Except for two panelists on hand for "authenticity," reporters were not allowed in the studio.

It was a shrewd way of presenting the candidate and a vision of America -- and bypassing the journalists. Asked why a pool of reporters wasn't allowed to observe, Shakespeare said they would just interfere with the message. Ailes agreed.

"It's a television show," he told Treleaven. "Our television show."

"On television it matters less that (the candidate) does not have ideas," wrote McGinniss. "He need not be statesman nor crusader; he must only show up on time. ... The TV candidate, then, is measured not against his predecessors -- not against a standard of performance established by two centuries of democracy -- but against Mike Douglas. How well does he handle himself? Does he mumble, does he twitch, does he make me laugh? Do I feel warm inside?"

In modern parlance, that translates as, "Would I have a beer with this guy?"

That shallowness still troubles some observers -- even admen.

"We're suffering from genericide," says Joey Reiman, who's worked with such companies as Delta Airlines, McDonald's and Procter & Gamble.

Not that Reiman is surprised: The higher the office, he points out, the more basic the appeal tends to be, so "as you're moving up to the presidency, the lowest common denominator are generic people." In that respect, perhaps it makes sense for campaigns to retreat behind blurry colors.