Dating site OKCupid is the latest Internet company to disclose that it conducts psychological experiments on users. OKCupid ran tests to analyze conversations while removing users’ pictures for several hours. The website also temporarily changed its profile-rating system and suggested dating matches for people with low-compatibility scores to see if they could sway the perception of one another, he wrote. While the move incited concern about privacy issues, Rudder said these types of tests are needed for websites to improve their products.

Co-Founder Christian Rudder’s blog post, titled “We Experiment on Human Beings!”, said the testing revealed a lot about consumer behavior on the dating website. The testing showed that the text in a profile is less than 10 percent of what people consider when rating other profiles. It was all about the picture. In the experiment where New York-based OKCupid displayed different compatibility scores than what the algorithm measured, he said the users were notified of the correct match score after the test.

“Guess what, everybody: if you use the Internet, you’re the subject of hundreds of experiments at any given time, on every site,” Rudder wrote. “That’s how websites work.” The disclosure follows an onslaught of complaints against Facebook Inc., which disclosed in June that experiments were conducted in 2012 to influence users without their permission.

While the study was for Facebook’s internal purposes, the temporary influencing of what almost 700,000 readers saw on their news feeds in January 2012 prompted a digital-privacy group to file a complaint with the U.S. Federal Trade Commission. The complaint stated that Facebook “purposefully messed with people’s minds” creating “emotional contagion.” Facebook tested changes in users emotional states by intentionally altering news feeds.