Technologists call it the Star Trek effect: show an imaginary sci-fi gadget on screen and, soon enough, scientists will be redoubling their efforts to bring it to reality. Minority Report, Philip K Dick's short story, which was filmed in 2002 by Steven Spielberg with Tom Cruise, is often put forward as an example. Since the film's release, a number of its featured technologies – touch screens, social networking, iris recognition – have become commonplace.

But, this week, another of its predictions – "intelligent" advertising – will become reality in London. (It has already been trialled in Japan and the US.) The children's charity Plan UK is to place an electronic ad hoarding by a bus stop on Oxford Street that can tell the gender of a passer-by using facial-recognition software to measure the distance between their eyes, width of their nose, length of the jawline and shape of their cheekbones. If it determines that the viewer is female, it will show a different ad to the one it shows men.

Privacy campaigners the Open Rights Group call the technology "creepy". Clear Channel, the company behind the ad, says no data about the passers-by will be stored. Coming next? Clothing adverts that display you wearing the outfit, apparently.