Facebook might be manipulating the content you see to determine how you react to it.

* Facebook published a paper showing that they manipulated the content seen by more than 600,000 users in an attempt to determine how it would affect their emotional state.

* The paper was called “Experimental evidence of massive-scale emotional contagion through social networks,” published in The Proceedings Of The National Academy Of Sciences.

* The Facebook Data Use Policy, gives the company the right to access and use the information posted on the site. Most data collected is used for advertising, but there’s also a bit about “internal operations, including troubleshooting, data analysis, testing, research and service improvement.”

Facebook is now becoming research lab, with all of our personal profiles becoming potential test subjects.

[More.](http://www.avclub.com/article/facebook-tinkered-users-feeds-massive-psychology-e-206324)