The images -- on TV, YouTube, our social networks -- have become so familiar that we take them for granted.

We're treated to scenes of Barack Obama with a group of middle Americans at a cozy restaurant table, then with an African-American woman in an office. Or we see clips from a rally, the president surrounded by faces of all ages and hues.

It's much the same with Mitt Romney: A quartet of white male engineers pore over plans, then an African-American woman talks with a colleague. We see shots of factory workers, then a burst of flags as the candidate heads for the stage. Or we get farms, children and a colorful audience at a speech.

More than 60 years into the Television Age, campaign messages have become a formula: Uplifting ads are full of inspirational music, flapping flags and stolid candidate portrayals; negative ones feature ominous melodies, dramatic black-and-white images and gloomy narrators.

Either way, they're often shot documentary-style, with shaky cameras and changing focus, so that live rallies look like commercials and commercials look like rallies. Whether live rallies or tightly scripted spots, almost all of it ends up on TV or the Internet, turning the campaign into one giant advertisement.

And in almost every instance, the people look like America -- or at least the idealized, multicultural mosaic we imagine the country to be, even including types once considered "edgy." One Obama ad shows a lightly tattooed woman; one Romney ad, perhaps the candidate's most pointed, includes a mother with a nose stud. Suffice it to say, these are not the sorts of images that would have passed muster even half a generation ago.

In the 24/7 world of presidential campaigning, all are welcome, all are included.

In some respects, perhaps this is a good thing. It's the "post-racial America" many hoped for with Obama's election, in which (to borrow some famous words) people would be judged by the content of their character, not the color of their skin.

We simply assume, says San Francisco State University political scientist Robert Smith, that "the norm -- and this is a good norm -- is an ethnically and racially diverse and egalitarian society," and the campaigns must reflect that.

But on another level, these images -- the optics - can be seen as a sign of timidity, as both major campaigns use diversity as wallpaper without actually engaging in the issues raised by a multicultural society.

"That sort of bigger vision, and a more adventurous sensibility, is something that's entirely lacking from this campaign. This is a small - bordering on minuscule - campaign," says John Carroll, a professor of mass communication at Boston University. Both candidates, he says, "are as risk-averse as possible."

And really, who can blame them? The electorate, we're constantly reminded, is evenly (and viciously) divided. Obama, already mistrusted by a portion of that electorate, doesn't want to poke at any beehives; Romney, trying to make a case he can help the sluggish economy, paints himself as a cool, technocratic fix-it man.

Neither candidate has ventured much into the wider America; the vast majority of their campaign stops since July 1 have been in battleground states, especially Ohio, Virginia, Colorado and Florida -- and even then, the candidates have generally stuck to inoffensive backdrops such as schools, farms, hotel ballrooms and the most generic of all, the airport tarmac. (Check out CNN's Campaign Tracker)

The days of spending time in the urban blight of the South Bronx (as Ronald Reagan did in a response to a Jimmy Carter appearance) or with South Central L.A. residents after the 1992 riots (Bill Clinton) seem long past. Sure, one of Romney's ads does feature him in gutted-out Detroit -- but he's seen driving by rotting houses from the remove of his driver's seat.

Besides, certain optics can only get you in trouble, as both Obama and Romney know. Who can forget Michael Dukakis, trying to demonstrate his defense bona fides, peeking out of a tank like a curious gopher? Or windsurfing John Kerry, whose Vietnam War heroism was turned against him by the Swift Boaters?

Indeed, both candidates have already seen it happen. The Obama campaign made hay with Romney's "47 percent" video, in which the former Bain Capital chief was recorded in front of wealthy fundraisers referring to Obama supporters as people who "believe that they are the victims, who believe the government has a responsibility to care for them." The president was slapped back after his lackluster, grimacing first debate, leading to a New Yorker cover that pictured him as an empty chair at a lectern.

The latter was a callback to a previously much-mocked event, Clint Eastwood's GOP convention speech, which was described by left-wing writer Jamelle Bouie as "an old white man arguing with an imaginary Barack Obama" -- by implication, symbolic of the GOP itself.

Which is what can happen when race and demographics are brought in the equation: the optics can become too symbolic. Better to keep the colors as hazy backdrops, the campaigns seem to suggest, rather than put diversity front and center - where it can become a flashpoint for divisiveness.

Looking at the details

Seeing how they work is the province of political scientists -- and some of them pay attention to the most trivial details.

To Costas Panagopolous, everything matters in an election campaign: the flag pins, the clothes, the camera angles, the audience. Everything makes an impression.

Panagopolous, a political scientist at Fordham University, watches how the candidates present themselves visually, whether on the stump or in advertisements. All this stagecraft makes a difference, he says.

"Studies reveal that the visual contextual elements can be very effective in engaging voters," says Panagopolous, who directs the university's Center for Electoral Politics and Democracy. Even peripheral details can make a difference, if only subconsciously.

In a recent study, Panagopolous sent postcards to Key West, Florida, urging citizens to vote. One set of postcards featured a palm tree, another an American flag, the third a cropped picture of eyes. The only postcard that stimulated voting was the one with the eyes, which Panagopolous attributes to the feeling of being watched.

It's yet another indication there's something within our psychology that's programmed to respond to certain messages, he says.

"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.