"Dating website OKCupid has revealed that it experimented on its users, including putting the 'wrong' people together to see if they would connect."

The whole thing is an experiment, but here's the revelation:

In one experiment, the site took pairs of "bad" matches between two people... and told them they were "exceptionally good" for each other.... "Not surprisingly, the users sent more first messages when we said they were compatible," Christian Rudder, one of the founders of OKCupid, said in a blog post on the company's research and insights blog.
Further experiments suggested that "when we tell people they are a good match, they act as if they are. Even when they should be wrong for each other." The company later revealed the correct scores to the participants.

In another experiment, OKCupid ran profiles with pictures and no profile text for half of its test subjects, and vice versa for the rest. The results showed that people responded solely to the pictures. For potential daters, Mr Rudder said that "your actual words are worth… almost nothing."