“But we have to acknowledge that these are human experiments. You’re trying to change people’s behavior.”

You’re not really trying to change people’s behaviour. You’re trying to show them the version of a website (for example) where you get more clicks based on their own pre-defined behaviour. Showing one group of people a green button and another group of people a blue button, and discovering that people click on the green one more often, isn’t an ethical issue — in my opinion, although I am a former digital marketer...