[r3bl]

I keep spamming this link, but it's important to be repeated: Facebook already intentionally manipulated emotions of a "small number of users" (700k), proved it was possible, and released a paper on it almost half a decade ago.

https://slate.com/technology/2014/06/facebook-unethical-expe...

[trishmapow2]

Link to paper: https://www.pnas.org/content/111/24/8788. (It does say 'massive-scale' though)