The ethics of human experimentation on the internet has been greatly debated, especially in light of the revelation that Facebook engaged in experiments on its users without their consent. Another site, OK Cupid, proudly states that they experiment on humans and whether or not you realize it, if you’re on the internet then you’re being experimented on all the time.
“We noticed recently that people didn’t like it when Facebook ‘experimented’ with their news feed. Even the FTC is getting involved. But guess what, everybody: if you use the Internet, you’re the subject of hundreds of experiments at any given time, on every site. That’s how websites work.”