I'm back from a week at my mom's house and now I'm getting ads for her toothpaste brand, the brand I've been putting in my mouth for a week. We never talked about this brand or googled it or anything like that. As a privacy tech worker, let me explain why this is happening. 🧵
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First of all, your social media apps are not listening to you. This is a conspiracy theory. It's been debunked over and over again. But frankly they don't need to because everything else you give them unthinkingly is way cheaper and way more powerful.
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Your apps collect a ton of data from your phone. Your unique device ID. Your location. Your demographics. Weknowdis. Data aggregators pay to pull in data from EVERYWHERE. When I use my discount card at the grocery store? Every purchase? That's a dataset for sale.
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They can match my Harris Teeter purchases to my Twitter account because I gave both those companies my email address and phone number and I agreed to all that data-sharing when I accepted those terms of service and the privacy policy.
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Here's where it gets truly nuts, though. If my phone is regularly in the same GPS location as another phone, they take note of that. They start reconstructing the web of people I'm in regular contact with.
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The advertisers can cross-reference my interests and browsing history and purchase history to those around me. It starts showing ME different ads based on the people AROUND me. Family. Friends. Coworkers.
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It will serve me ads for things I DON'T WANT, but it knows someone I'm in regular contact with might want. To subliminally get me to start a conversation about, I don't know, fucking toothpaste. It never needed to listen to me for this. It's just comparing aggregated metadata.
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Replying to @RobertGReeve
As someone that works in the ad industry: campaigns with targeting as you describe are never that precise - at least in my experience. It looks more like “people that have interest in gardening that are 40+ in x geo’s”

12:40 PM · May 26, 2021

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Like, most campaigns I run I want to see Return On Ad Spend. Clients want to make money in their investment. They’re not advertising to hopefully subliminally catch someone that may or may not tell a friend to purchase their toothpaste. That would be a WASTE of their ad spend.
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It’s a great point. Also, all purchase-based data (like that from grocery loyalty cards) is modeled out to protect consumer privacy. So the advertiser isn’t reaching all people who’ve purchased a product, they’re reaching those people and others who look/behave like them.
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To expand a bit on what you said. Targeting is never that specific, but the people who decide what users you target when you say “likes gardening” have more granular data. Generally at the household level. So in Robert’s case he probably just got lumped into the same household.
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