If you have a smartphone, you have had this unnerving experience at some point: After having a face-to-face conversation with a friend or a partner in a private setting, you pick up your phone and see ads on social media that echo the details of your chat to an uncanny degree—ads for picnic baskets after a discussion of weekend barbecue plans, or a sale on flights to a place you just mentioned wanting to visit.

The less tech-savvy (or more conspiracy-minded) among us might worry that an app or the phone itself is somehow recording our conversations. This is not true—though if you’re still not convinced you can change the settings on your phone to reduce the amount of data apps can collect.

Tristan Harris, a former Google design ethicist whose “Time Well Spent” movement aims to reclaim time and attention from digital devices, explained what’s actually going on with those spot-on ads at a recent panel at the Milken Institute Global Conference in Los Angeles. No secret recording is involved, but his description still offers eye-opening perspective on the amount of data advertisers have at their disposal:

I know for a fact, the data forensics show, and the Facebook VP of advertising says, promises, that they do not listen to the microphone. How is it they’re still able to know the conversation you had? It’s because inside of a Google server or a Facebook server is a little voodoo doll, avatar-like version of you. Like a model of you. And I don’t have to listen to your conversations because I’ve accumulated all the …clicks and likes you’ve ever made, and it makes this voodoo doll act more and more like you. All I have to do is simulate what conversation the voodoo doll is having, and I know the conversation you just had without having to listen to the microphone.

So no, tech companies aren’t secretly listening to your IRL conversations. They know you so well that they don’t need to. You can watch the whole discussion here.