I use Whatsapp only for communication with office colleagues. I had my Instagram linked to my mobile number(2fA). Soon my office colleagues' profiles started showing up on my Instagram follow suggestions. This happened despite the fact that I have not uploaded my contact list to Instagram. I had to block all my colleagues on insta, and then remove my number from Instagram profile.

"how well can this be actually used currently to create a proper psychosocial(?) profile of an individual? What's the current state of the art? Any suggestions for books or papers to read on the matter?"

I suspect quite poorly.

It's 2018 and I've been hearing pitches and narratives to do with fancy targeting of advertisements and user profiling now for 22 years.

And what do we have ? If I search for something obscure related to an (product), I will see unbelievably blunt and almost comically generic (product) ads for a week. Even if my search makes it obvious that I am not a prospective customer.

What advertisers receive for their money on these platforms is laughable and I am sure there's a complicated sales pitch with graphs and fancy terms of art and mentions of "AI" ... and it's all just bullshit, just like it has always been.

I had one incident which convinced me that their algorithm is easily fooled even by single misclick.

I hate ads propagating alcohol so I always report them to FB. Once I misclicked and instead of reporting it I opened linked article. Based on that click FB added alcohol to my interests. It did not matter that I reported all other similar adds before and also after that.

Whether the algorithms seem effective to you, as a single consumer of the advertisements, is irrelevant.

Facebook ad campaigns most definitely work (though I'd imagine there's some variance of effectiveness based on what exactly you're trying to sell with the ad campaigns), and lookalike audiences are an effective way of determining who to show your ads to.

It's really quite simple, as a company you can spend money on Facebook ads and you will get traffic/conversions/etc.

I agree. But I reacted on comments disqusing if this algorithm is capable of doing more than targeting ads to make them cost effective.

That's part of the reason I asked. Based on the ridiculously bad suggestions I'd often get (from search, netflix and the lik, etc.), it all seemed a bit too much hot air.

But a few things made me (sort of) change my mind over time, and worry more actively:

1. the ability to properly use the data available is a skill in itself. The fact that this 'new, non-private' internet is still relatively young (really just a decade, post-smartphone I'd say) could mean that most companies/governments simply didn't know yet how to properly use it. Considering the many examples of the slowness with which organizations tend to adapt, that doesn't seem unlikely.

2. There's a huge difference between the data available, and the targeting achievable pre-smartphone, and post-smartphone. On top of that, I distinctly remember that throughout most of my youth (so up until a few years before world-wide Facebook) it was still very much a 'default' attitude to be very careful about your personal information online. Not quite the "don't go into chatrooms" of my childhood, but still the "don't use your real name, ideally, on <national social network>".

3. We've made quite a number of advances already in storing and analyzing 'big data', from what I understand. And a decade or two of research on this new world of personal internet data must have led to some significant advances, no? I mean, so far we've gotten really good at manipulating people with whatever new technology entered the scene. Just not right away, necessarily.

4. from personal experience, and conversations with people who do/did targeted advertising on Facebook, it really does seem shockingly easy to target specific messages to specific groups. I find it hard to believe that this does not fundamentally change the whole game of manipulation, compared to things like TV and newspapers. Hell, 'old fashioned' direct marketing / door to door sales is perhaps a precursor of all this. I remember reading quite a while back how advanced the techniques were to decide what neighborhoods to visit or snailmail-spam for particular products or services. If companies were willing to spend the amount of money necessary for that, it must have some effect. Being able to target essentially large parts of the entire world in that same way has got to be at least somewhat more powerful, which is scary enough maybe.

I'm not sure of any of this, though. Just thinking out loud and very curious to hear what others think (although ideally I'd also love some suggestions of where to find the best research/articles on the matter).

regarding 1, I recall reading that 23 likes are enough to guess a persons sexual orientation with better accuracy than close colleagues can. Couldn't find a source on this in 5 minutes though.