General Motors has come a long way from its 1959 Cadillac ad that began, "One of the special delights which ladies find in Cadillac ownership is the pleasure of being a passenger," and went on to invite women to visit their local dealer "with the man of the house" to try out the passenger's seat.

The company is now taking a different advertising approach--namely with Chevy's #SheBelieves campaign which features women athletes and professionals--because, as GM's CEO Mary Barra says, gender equality is about more than making the brand look good.

"I wouldn't be sitting here if diversity wasn't valued 20 years ago," Barra said from a stage shared with Facebook COO Sheryl Sandberg and Procter & Gamble's Chief Brand Officer Marc Pritchard. They were speaking on a panel about cultural change in a mobile world at New York Advertising Week.

That's why she's working to include positive female images in GM's advertising--a cause Procter & Gamble's Pritchard is behind as well. "Unconscious bias comes from years of accumulated messaging from advertising," Pritchard said.

Advertisers have an opportunity to address stereotypes head on. Take, for example, an ad for Procter & Gamble's laundry detergent brand Ariel in India, which shows a father watching his daughter zip around her kitchen--firing up the stove, opening her laptop while fielding a work call, nodding at a request for dinner and laundry from her husband. His apology to her is delivered via voiceover: "Sorry that I never stopped you, while you were playing house. I never told you that it's not your job alone...but your husband's too." The father has an epiphany that he can do one simple thing to help his own wife out around house, and the ad ends with a powerful onscreen message: "Why is laundry only a mother's job?"

Putting your brand behind a message like this and realizing it's an effective way to sell products, is the biggest contribution a company can make Sandberg says. After all, she points out an advertisement has the potential to reach more people than even a best-selling book.

Plus, positive messaging coming from the company has the added benefit of keeping employees engaged and proud of where they work. Sandberg says that, just like people make decisions about what products to buy each day, they decide whether to come to work and how much to dedicate themselves. It's a sale you have to make every day, says Pritchard, and a sense of mission makes a huge difference.