Whether you're buying macaroni and cheese or a pair of designer jeans, there's a new spy in town watching you and wondering why you shop the way you do.

It's your shopping shadow.

Armed with a video camera and a Ph.D., Shelley Balanko is snooping.

She wants to know what makes people tick. She approached Denise Schwend to find out what moves the stay-at-home mom, why she volunteers.

"Well, I was raised that way," Schwend told her.

But Balanko wasn't done. She wanted to know Schwend learns about organic products, how she handles a hectic schedule.

"I'm not gonna stay up until midnight just to make meatballs. I need to sleep, too." Schwend told her.

Schwend opened up her home, her cupboards and refrigerator to the researcher from Bellevue's Hartman group. Corporate clients think the information Balanko collects is worth millions.

Balanko makes house calls instead of phone calls to explore shoppers' habits.

"Over the phone, you don't understand a person," she said.

And at Schwend's home, she found out the stay-at-home mom makes small trips to a nearby QFC, but prefers to do most of her shopping at Trader Joe's.

Information like this - how consumers live and what they value - is priceless for companies that use the knowledge to market to customers.

"Denise gets most of her information from social network. That means companies need to talk to the people important to her life," Balanko said.

Balanko follows people to stores, parties and even bathrooms.

While companies like Kellogg and Kraft pay big bucks for research, volunteers like Schwend get a small check for her time. But as a socially-conscious consumer, her pay is not Schwend's main incentive.

"I don't want any more yucky products; I want stuff that I wouldn't care about if my son accidentally eats them," she said.

The Hartman researchers travel across the country to study shoppers' habits. They say Seattle is a trend-leading market.