If you happen to be looking at an advertisement on a video screen in a mall, health club or grocery store and there’s a slim but growing chance the ad is watching you too. Small cameras can now be embedded in the screen or hidden around it, tracking who looks at the screen and for how long. The makers of the tracking systems say the software can determine the viewer’s gender, approximate age range and, in some cases, ethnicity and can change the ads accordingly. That could mean razor ads for men, cosmetics ads for women and video-game ads for teens, Yahoo! reports.