Ask HN: Girlfriend is being shown ads depending on what we do together. How?

I am not in this field and I believe some guys here already explained it much clearly than me.

1. Checking Open houses: Many apps are authorized by most users to access their location. Ads space providers qualify their data, that is the way they earn their life. Then if one Ad client works in real estate, the Ads space, sorry your girlfriend phone screen, is a nice target for real estate Ads.

2. Kung fu ads: A Ads space provider for some of the ads may have noticed that several different user agents come from the same IP adress, so it inferred incorrectly that they belong to the same person.

> Is this what the Internet is like for "regular" people? If so, holy shit. I'm glad I use uBlock Origin on my computers and an iPhone.

Somewhere, in a dark corner in a AWS datacenter in Oregon, some third-party tracking software records "Hey, the only user within five-mile radius that blocks our ad links just finished watching a kung fu movie."

Besides ad-blockers, turn off location tracking in apps. I forgot how it is for Android, but in iOS you can disable location tracking on an app-by-app basis. And you can also partially disable it -- only allow it when the app is active, as opposed to background tracking.

It seems to me as though this is the exact reason that Zuck was called in to testify. We have a reasonable understanding and can at least comment intelligently, but the public sees this, and clearly calls fowl. Being unable to stop it, they demand action from their senators. There's a reckoning coming I reckon --- it reminds me of GDPR in Europe.

It could just be targeting. While it's possible something nefarious is going on, advertisers are really good at using available data to predict information that was never provided. In the case of the kung fu movie, it's possible IP address was used. For the open house, there could be some location correlation, but I would bet it's more than that (age, financial profile, relationship status). You can feed a bunch of data about someone to an algorithm and predict these things with pretty high confidence.

The way to avoid this is to opt out of interest based ads. iOS and Android both have options for this.

My guess would be:

1) Facebook (ie instagram) knows you are in a relationship

2) Facebook knows girlfriend's location from being signed in (on Instagram)

3) Facebook knows locations are at open houses from data gathered from other users or around the web. Or maybe Facebook knows that going to a few totally new random residential locations in a short period of time, combined with girlfriend's other engagement activities means user is looking for a new place to live.

Start by switching to iOS, then for each app she installs make sure location permissions are denied. On the laptop, make sure uBlock Origin is installed.

This was happening to me until I removed Facebook and Facebook Messenger from my phone. I believe these apps listen to conversations even when you aren’t using them. I am not alone in believing this.

1. Did she discuss looking at houses with you or anybody in emails or social media messages?

2. Did her smartphone location ever correspond with a house that is listed on the MLS in the past week?

did you invite her to come see the open house by texting her "hey, wanna come see an open house"?

Did either one of you login to amazon, Facebook, google, etc on one of the other persons device? If so there is likely still a tracking cookie associating you with her device. And your searches are causing her device to be targeted.

A totally plausible explanation for this (as plausible as any Amazon Echo passive speech recognition ad targeting theory) is that she's been seeing these ads for weeks, but they were completely irrelevant and her mind filtered them out until she happened to have house hunting / martial arts movies on her mind after these events.

> Is this what the Internet is like for "regular" people? If so, holy shit.

Presumably. Even with the best precautions (ad blocking, etc) some tracking still slips through the cracks. I don’t want to imagine what it’s like for the average idiot who installs every single crappy app, gives it all the permissions and logs in with their Facebook account into them.

Did you guys use zillow/trulia to look up listings?

I don't know how this is happening exactly, but I want to add that it has also been happening to myself and to my friends for quite some time.

I have worked for a number of ad tech companies over the years.

If this really is happening (and it seems possible it could be coincidence) the most likely explanation is cross device targeting using IP address.

So, most ad tech companies do cross device targeting, using device maps bought from other companies (Drawbridge being one). These companies attempt to assign a variety of devices from the same person to a single advertising profile. The simplest way they do this is by IP address. So if they have an IP address with a small number of devices, they decide it is probably a household and assign all those devices to the same advertising profile.

So, by being on the same wifi together (either at your place or hers) they will show ads on her devices based on your behavior (and vice versa).

The other explanations are possible, but I think this is the most likely

The Facebook app tracks location and other peoples' locations, and makes assumptions based on people being at the same place at the same time. If Facebook (or whoever) knows that several other people are all interested in new houses, and all those people + your girlfriend go to the same place(s), Facebook decides that your girlfriend might have the same interest as all those other people.

This kind of "air-gap join" definitely happens based on my own experience. e.g. I get shown ads for products my kids are interested in, where I am sure I never interacted in any way online with the vendor. Also I had a /24 IP block and used some addresses for my neighbors' connections (different to our IP but within the same block). Neighbors reported seeing ads for products we bought. In fact we would joke about it, ask each other why we were seeing ads for xxx weird and unusual thing.

I'll guess that the following join keys could be used:

IP address or IP address subnet Physical location / postal address Known family or romantic relationship Offline key match such as use of the same credit card

Note that this is not data leaking from one person to the other. Here the ad networks know specifically that the two people are doing stuff together, but that they are not the same person.

If you have enough data point for enough people in a large enough area, well machine learning will do the trick[1].

[1]: https://idiallo.com/blog/machine-learning-ads

This is the result of all the years of data mining and tracking. Now they can see your phone is at an open house and make an educated guess (which is all it is), that you're interested in buying homes.

All your web traffic is tracked too, unless you only use sources that explicitly do not track, such as duckduckgo.com. Check out https://ssd.eff.org, you might find it helpful.

Since the video of the guy talking about dog toys with chrome closed, and then seeing dog toy ads shortly after, I've become skeptical of this. So, I've begun testing it myself. I thought of something somewhat specific but random, unrelated to me, unlikely for me to see regular ads for, and now from time to time I talk about that thing. Until maybe a few weeks from now when I stop doing this, I will not be typing the thing, or anything too closely related, into any kind of text field.

I've been doing it a few days so far and nothing yet.

Suppose I operate a small general practitioner healthcare facility that often has only two patients at the same time. If I offer free Wi-Fi in the waiting area, should I consider that a HIPAA violation, because I'm reasonably confident that one patient will see ads related to the other patient's medical condition?

The brilliance and scariness of the possibility that this may be where advertising technology is at reminds me of this sentiment that I can't remember the source of:

"All the brightest human minds in the world are working for advertising companies"