7 ways companies watch you without your knowledge

Walking down the street, heading from one airport terminal to another or driving through town, you'll come across many billboard ads. Typically, you may barely glance over and give them not a thought.

But they may be paying much more attention to you.

A recent New York Times story described how a political poster in Mexico City was outfitted with a camera so facial analysis software could read emotions. The campaign would then make small adjustments to the message to see if it could gain more positive feedback.

That may be pretty novel for political campaigns, but they're late to the game. Corporate marketers have been doing all this and more for years, and continue to look for new ways of understanding more about you. Not the general "you," but you in particular. Here are some of the technologies they use to achieve their aims.

Facial and body recognition

Using software to identify gender and approximate age of people has been around for years. Such technology has even been used to display products considered appropriate to that age and gender. Software to recognize specific faces is also used to customize marketing campaigns to specific individuals.

Retail tracking

Retailers are following consumers through their smartphones and through cameras. The aggregated data help companies more effectively lay out stores. In addition, if you know the individual -- and the unique identifier that each phone has can make that possible -- you can start to intelligently guess what she's interested in and address that in individualized marketing campaigns. Some companies are trying to expand such tracking beyond a store's walls, as well.

Smartphones

In addition to retail tracking, smartphones offer a wealth of data. Using services from Google (GOOG) or Apple (AAPL), for example, help them know where you are and what you're doing. If you've granted the relevant permissions to an app when you installed it, the software might have access to such data as your current location or your contact list.

Email

Although you may think of email as private, if you're using a service like Google Gmail or Yahoo (YHOO) Mail, one price of access is permission you've given to scan through all emails you send and receive. Although some companies have argued that scanning isn't like having people reading the emails, it's ultimately worse. All of the information gleaned can be added automatically to an ever-increasing dossier.

Behavioral marketing

Behavioral marketing has become a standard set of tools and techniques that allow companies to follow your activities all over the Web, tracking what you look at, read or buy. The concept is to build a profile that gives clues to who you are and what you want, and in the absence of blocking software that can keep the tracking from happening, it occurs every minute you're online. New technologies can expand that tracking to activity on a mobile device's browser as well.

Data portfolios

Data brokers collect massive amounts of information from public records, information given to companies you do business with and other sources. These become a repository that let the brokers have a sense of what you do and your net worth, current interests, financial transactions and more.

Social networks

Facebook (FB), Twitter (TWTR), Instagram and other services have offered new ways for companies to follow what you do. Many people forget to use privacy tools to limit who has access, which means companies can also see your posts, images and location check-ins. Some can tie your identity to other sources of information, providing an even richer view of your life.

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    Erik Sherman is a widely published writer and editor who also does select ghosting and corporate work. The views expressed in this column belong to Sherman and do not represent the views of CBS Interactive. Follow him on Twitter at @ErikSherman or on Facebook.