[zaroth]

It seems to be that Facebook did something like an A/B test of their ranking algorithm, and then did a cohort study to see if there were any longer term impact.

If what they did requires informed consent, what about when the end goal is maximizing click through rate, e.g. by inciting an emotional response?

Let's say FB finds that certain types of posts in the feed cause a nearby ad to be clicked on more. They determine this through pervasive testing of everything that you see and do on their site. They could then adjust their algorithm to account for this behavior to increase clicks/profit.

I think the actions FB takes to monetize the user base are not only more intrusive by far, they are actively searching for and exploiting these effects for profit. If informed consent for TFA is not ridiculous, then I think we have much bigger problems on our hands? What am I missing about the informed consent issue?

[kevingadd]

You're not missing anything. Informed consent is important for many things currently classified as A/B tests and it isn't currently acquired by anyone. There are many existing products that rely on A/B tests to identify the best way to psychologically manipulate (if not addict) their customers (F2P games, online gambling, etc.)