Here's how I know Google knows too much about me -- California bat protection

Sometimes Google's ad-delivering algorithms reveal just how much the company knows about you, such as the contents of your email. I found this out in a personal way when a month ago Google delivered an odd ad to me in Gmail from a service promising to protect me against bats in California.

I live in Cambridge, MA, and about a month ago I was visiting my daughter in San Francisco, and had taken along a Macbook Air to work while I was there. I used Google Maps regularly to find various locations around the city, including finding walking and driving directions.

My brother and his wife at the time were vacationing in New Zealand and Australia, and he sent me an email describing a remarkable cave they had just visited, home to many thousands of bats.

I finished reading the email in Gmail and went back to my inbox. And there, at the top of my inbox was an ad for a service that promised to rid Californians of bats in their homes. Why was Google delivering that ad to me, a Massachusetts resident whose home wasn't prone to bat infestations? Clearly it was because Google recognized that I was in California and reading about bats, so assumed I live there and my home had a bat infestation.

Google is upfront about doing this kind of thing. On a page titled "About personalized ads on Google Search and Gmail," it has this to say:

When we personalize ads, we display ads based on the contents of all your emails. For example, if you've recently received lots of messages about photography or cameras, we might show you a deal from a local camera store. In your inbox, we might also show you ads related to information from different emails in your inbox.

You can block some of this. When you're in Gmail, click the "Why this ad?" link on the upper right of the screen, then from the pop-up box, click "Ads Preferences Manager." From that page, you can block a specific advertiser. You can also head to a page that lets you opt out of seeing personalized ads...sort of, that is. The page notes that:

After opting out, you'll still see relevant ads, but Google won't use additional information to personalize those ads on Google search and Gmail.

I'll admit to being confused by that. How can Google deliver relevant ads if it isn't using information from your search history and Gmail inbox to figure out what's relevant?

This small incident is just one more example of why Google and other Web sites need to come to terms with people wanting their privacy protected. It's certainly true that a great deal of money is at stake for companies like Google, and the money contributes to the success of the Web; personal information about people's interests and Web habits are worth quite a bit. But there has to be a balance, giving consumers some way to protect their privacy as well. I know that from personal experience, even if I dont' need California bat protection.

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