A charity trying to improve life for girls has launched an interactive advertisement designed to give males a brief taste of discrimination.

Plan UK has launched the ad in a display on a bus stop in London’s Oxford Street, the British capital’s busiest shopping district. The display, which will be in place for two weeks, includes a camera that attempts to detect the gender of the person standing immediately in front of the ad space.

If the person is detected as female, she is offered the chance to press a button and see a 40 second advert about the charity’s campaign. If the person is detected as male, he simple sees a message referring him to the charity’s website, along with statistics backing up the campaign, such as 75 million girls being forced to leave education early.

The stunt is designed to highlight what it calls discrimination against girls worldwide as a result of poverty and discrimination. It’s aim is to “help 4 million girls through education, vocational training and improved opportunities.” The charity says that despite the advertising technique, it wants males to contribute to the campaign as well.

Although the total cost of installing and running the advertisement is £30,000 (approx US$50,000), the charity believes it will help it meet its target of raising £250,000 (approx $400,000) over the next four months.

The facial detection works by measuring a variety of features including the length of the jawline, the width of the nose, the distance between the eyes and the shape of cheekbones.

It’s said to guess gender correctly 90 percent of the time, which may be sufficient for use such as this (there haven’t been reports yet of users being outraged at being misidentified), but wouldn’t be close to accurate enough if there were genuine consequences from getting the gender wrong.