Christian Rudder is mild-mannered in person. But in his official capacity as the president of OkCupid, an irreverent online-dating site, he likes to provoke.

The job allows Mr. Rudder, a 39-year-old Harvard math grad, to study the calculus of human attraction. He oversees OkCupid’s in-house research into the predilections of millions of its members. To drive traffic to the site, he publicizes the results on a company blog, often delving into volatile themes — like members’ attitudes toward the appearance, age and race of potential dates.

“That’s the OkCupid cocktail right there,” he told me over coffee one recent morning near his home in Brooklyn.

So it seemed only natural this summer, after Facebook came under fire for a research study in which it manipulated content viewed by a subset of its members, for Mr. Rudder to piggyback on the controversy. In a blog post — with the button-pushing headline “We Experiment on Human Beings!” — Mr. Rudder announced that OkCupid, too, had manipulated information seen by some users.