Is technology going too far? I think much of it is now used to keep an eye on our every movement and to listen in on our every thought. The other day I walked into a shop and was faced by a TV screen enticing me with details of a special promotion for the brand and design of shoe I was about to go and buy. How did they know?

This hasn't actually happened yet but it could be the situation soon when advertising companies start to use face recognition technology. We are already faced with targeted adverts when we use our computers. These are based on our web browsing history. But this kind of surveillance is creeping into our off-line life. Facial recognition cameras are already being fitted to billboard screens so that advertising companies can monitor the sort of people viewing commercials at each location.

I often stare at these TV screens when I'm waiting in a queue at a shop - there is not much else to look at - but it is scary to think that the screen might be looking back at me and analysing my traits. It will, for example, work out my age and sex. I would be insulted if it got it wrong!

Amscreen, one of the companies rolling out this technology, claims more than 50 million people around the world are seeing its screens each week in places like doctors' waiting rooms, airports and petrol stations. They can be very powerful marketing tools.

The fashion brand, Burberry, is trialling another type of technology. When customers wearing its clothes stand in front of "magic mirrors" - screens start showing footage of how the clothes looked on the catwalk when modelled with other Burberry goods. It seems we will have nowhere to hide from these marketing spies!

Campaigners are warning there must be limits and that our privacy must be protected. Big Brother Watch is a group that fights to protect privacy. Its director, Nick Pickles, says: "Are we willing to accept our everyday movements being monitored and analysed, not to keep us safe but purely to allow advertisers to target us? I think people will start to say no, our privacy is worth more than a few advertising dollars."

Hopefully this new technology will just be a short-lived marketing gimmick. If not, I will choose where I shop and make up my own mind about what I buy.