[maxfurman]

Every one of my friends, including me, has a story about how they used a phrase in conversation that they don't typically say ("Renaissance Faire" in my case, which I have never attended and generally have no interest in), and then seeing an ad for it on either Facebook or Instagram right afterwards. This is purely anecdotal, of course, but it is creepy anyway. The only way to stop this "myth", if it is one, is for Facebook to stop doing whatever it is they do instead of listening to us to get to this unnerving level of targeting.

[mverwijs]

Alternate explanation: the person(s) you discussed this with did some google'ing and browsing. The tracking cookies do their thing and since you and those persons are linked, you end up with the ads served.

[cryoshon]

a good alternative hypothesis, but also one that should be proveable, at least in some cases.

designing an experiment to test this would be quite easy.

ultimately your explanation could exist alongside audio snooping, perhaps even helping to resolve areas of ambiguity...

[phpnode]

Is this repeatable though? It seems like this could be explained by a combination of the Frequency Illusion / Baader-Meinhof Phenomenon[0] and the Birthday Problem[1].

That is - it is possible that the reason you were discussing the topic is the same reason that advertisers were targeting that particular phrase at that time. The Frequency Illusion could explain why you noticed that particular ad and why you were surprised. Also you presumably discuss topics all the time that you don't see ads for, but the probability of seeing an ad for any of those topics is quite high (the birthday problem).

[0] https://english.stackexchange.com/questions/153166/what-is-t...

[1] https://en.wikipedia.org/wiki/Birthday_problem

[npkarnik]

100% - I'm not sure why others are so dismissive. It's not that technically difficult, and FB has a reputation for being creepy. If only I could figure out how to get random one night stands out of my "People you may know" list...