Party leaders surrounded by planted supporters during campaign stops

With a bright purple-striped head scarf, Rubina Razique stands out in a crowd of NDP orange.

And that's no accident.

The people who line up behind the party leaders and obediently smile, clap or laugh, may outwardly act like trained seals performing on cue, but without them, the political photo op would be far less effective.

In Razique's case, she and her sister Sadia were given front-row seats for NDP Leader Tom Mulcair's recent rally at Surrey's Bear Creek Park in B.C.

"I wanted to show people that I'm supporting the NDP and I am supporting them every single day," she told CBC News.

Subliminal messaging

Perhaps, but it's likely party organizers were trying to send another message too, says UBC political scientist Edana Beauvais.

The niqab has become a wedge issue, particularly in Quebec. and Conservative Leader Stephen Harper has said he would consider banning public servants from wearing it.

"I don't think it's an accident she's placed there," says Beauvais. "I think that they are reinforcing the idea that women can wear whatever they want and they are welcome in the NDP."

Beauvais says every party uses its supporters as a form of human wallpaper to channel messages and to form an association with voters.

For example, recently Harper was in Whitby, Ont., for an announcement on jobs in the auto sector. By and large, the people surrounding him were middle-aged white men.

"He doesn't want to say explicitly, 'Hey men between the ages of 40 and 65, I'm targeting you,'" says Beauvais.

"Instead, he wants to be more implicit about it. He has them sitting in the background. Viewers at home can see this image and maybe they see themselves there and identify a little more with what they are saying," she says.

Of course, the human props in photo-ops don't always do what's expected of them. In the midst of Mulcair's big announcement in Alberta Tuesday about education for First Nations, the cameras caught a First Nations leader sitting beside him reading messages on his smartphone.

And earlier in the week, Juno-award winning musician Ken Whitely stole the show at another Mulcair event by wearing a striking lavender sweater that took the focus off the leader of the NDP.

Political 'potted plants'

In August, Harper and the Conservatives ran afoul of the Scouts of Canada after using some uniformed youngsters for a photo-op in Campbell River, B.C. The event apparently violated the Scouts' no-politics rule.

More often than not though, the so-called political "potted plants" perform as expected.

Liberal Leader Justin Trudeau was at the train station in Sussex, N. B., Wednesday surrounded by a group of local firefighters who were all supporting the local Liberal candidate.

John Codling told CBC News the experience of sharing the stage with a party leader was "inspirational."

He said the instructions were simple and he was happy to do as asked.

"Just try to smile and be supportive."