Advertisers watching everyone closely on Facebook

Wonder why certain ads pop up on your Facebook page?

If you're young and female, you're likely to be bombarded with ads for tampons, teeth-whitening and even cervical screening.

If you're a young guy, you're more likely to see body-building or computer game promotions.

If you live in Auckland, you'll get Auckland-focused ads. Ditto with Hamilton, Wellington or Christchurch.

Yes, advertisers are watching you surprisingly closely - and it makes little difference what privacy settings you activate on your profile.

Facebook says it "does not give advertisers access to the personal information you choose to put on the site. Advertisers will be subject to all of the privacy settings you have in place on your account, and will only be able to see your profile or other information if you've allowed them to do so".

What it fails to mention, however, is that "basic information" is separated from "personal information". If the "basic information" section is filled in, advertisers can see it and make use of it.

Users can include as little or as much of their "basic information" as they like, including age, gender, birthday, hometown, relationship status, "interested in", "looking for" and political or religious views.

"Personal information" is another goldmine for advertisers - this is where you fill in things such as activities, interests, favourite music, films, books and movies.

Unlike "basic information", however, users can choose to make this information private, so only friends can see it.

The Herald on Sunday decided to test just how much advertisers know about us from our Facebook profiles.

In the name of research, this reporter, a 24-year-old female who has her settings set to private, changed her relationship status to "engaged". Within an hour, ads were popping up for wedding providers and jewellery stores.

"Our goal is to deliver ads that are not only valuable to advertisers, but also valuable to you," says Facebook's "Statement of Rights and Responsibilities".

Advertisers are encouraged to "target your exact audience with demographic and psychographic filters about real people".

Of course, Facebook users can only be targeted if they publish the above information on their profile, and they're not obliged to reveal any information at all about themselves. But the more you reveal, the more you should expect to be targeted by advertisers.

Facebook user Lucy Chapman says despite having very little personal information about herself on her profile, she often gets targeted by advertisers.

"I get ads in French because I spent some time in France," says the 24-year-old. "I've also gotten Arabic ads after I've communicated with Arabic-speaking friends on Facebook. It's ridiculous."

According to New Zealand online marketing site First Rate, more than a million Kiwis are signed up to Facebook. The average user makes 24 visits per month, spending about 22 minutes on the site each time.